ARADUR 3987

ARADUR 3987 is a high-solids waterborne modified polyamine-adduct epoxy curing agent developed for two-component aqueous coatings where high reactivity, chemical resistance, thermal resistance and compatibility with multiple epoxy-resin technologies are required. The commercial grade is supplied as an approximately 80% solids liquid in water and can be used with liquid epoxy resins, liquid-resin emulsions and solid type-1 epoxy dispersions for coatings and layers on mineral and metallic substrates. ARADUR 3987 is especially useful when formulators need a concentrated waterborne hardener that introduces less carrier water than lower-solids aqueous curing agents while still providing short curing times and flexible resin-selection options.

PRODUCT IDENTITY

Product name: ARADUR 3987
Product type: Waterborne epoxy curing agent / hardener
Chemical family: Polyamines
Specific chemistry: Modified polyamine adduct dissolved in water
Carrier: Water
Physical form: Liquid
Appearance: Clear liquid
Color: Gardner ≤8
Odor: Faint amine odor
Solids content: Approximately 79-81% by weight
Water content: Approximately 19-21% by difference from solids content
Viscosity at 25°C: Approximately 15,000-30,000 mPa·s
Amine value: Approximately 200-250 mg KOH/g
Active hydrogen equivalent weight: Approximately 147 g/eq as supplied
Density at 23°C: Approximately 1.1 g/cm³
Flash point: Greater than approximately 100°C 
Recommended mix ratio with ARALDITE PY 33757: Approximately 100:83 parts by weight
Recommended mix ratio with ARALDITE PZ 3961-1: Approximately 100:28 parts by weight
Historical hardener-adjustment guidance: Depending on application and required properties, approximately 80% of the recommended hardener amount may be preferable
Primary functions: Curing agent, hardener and crosslinker
Primary application class: Waterborne coatings
Suitable epoxy-resin forms: Liquid epoxy resins, liquid-resin emulsions and solid type-1 epoxy dispersions
Historical liquid epoxy example: ARALDITE GY 776
Historical liquid-resin emulsion example: ARALDITE PZ 33757-67
Historical solid type-1 resin dispersion example: ARALDITE PZ 3961-1
Primary substrates: Mineral substrates and metallic substrates
Key performance characteristics: High reactivity, short curing time, high chemical resistance and high thermal resistance
Benzyl alcohol: benzyl-alcohol-free
Storage temperature: Approximately 2-40°C in sealed original packaging 
Direct sunlight: Storage away from direct sunlight is recommended
Stirring before use: TDS instructs stirring before use
Historical shelf life: Approximately one year at the stated storage temperature, with the original-container expiry date controlling
Hazardous decomposition products in fire: Carbon monoxide, carbon dioxide, nitrogen oxides and other toxic gases and vapors
CAS Number: Commercial waterborne modified polyamine-adduct mixture; no single CAS number should be assigned to the complete trade grade without the current SDS
EC Number: Commercial mixture; no single EC number should be assigned to the complete trade grade without the current SDS
Molecular Formula: Not applicable to the complete commercial mixture
Molecular Weight: Variable / not applicable as one fixed molecular weight

ARADUR 3987 should be treated as a proprietary waterborne modified polyamine-adduct curing-agent mixture rather than as one discrete molecular substance. The active curing-agent phase contains a distribution of amine-containing structures and is supplied in water, so one fixed molecular formula, molecular weight or universal trade-product CAS number would not accurately describe the commercial grade. Current product-specific SDS documentation should be used for formal component identity, concentration ranges, regulatory classification and transport information.

WHAT IS ARADUR 3987?

ARADUR 3987 is a highly reactive water-emulsifiable amine-adduct curing agent designed for waterborne epoxy technology. Its defining formulation advantage is the combination of high active-solids content with compatibility across several resin-delivery forms, including liquid epoxy resin, liquid-resin emulsion and solid type-1 epoxy dispersion.
The product can therefore be used in a wider range of waterborne system architectures than hardeners that are limited to only liquid epoxy emulsions or only solid resin dispersions. This versatility allows formulators to choose resin technology according to target film build, dry time, chemical resistance, substrate and application method.

ARADUR 3987 is supplied at approximately 80% solids, so the hardener introduces relatively little water compared with products supplied at roughly 40-55% solids. Lower carrier-water burden can support faster physical drying, higher wet-film solids and reduced shrinkage during water loss.
Technical literature emphasizes high reactivity, high chemical resistance and high thermal resistance. These characteristics make the grade particularly relevant to protective coatings, industrial maintenance systems, civil-engineering coatings and selected marine or mineral-substrate applications.

MODIFIED POLYAMINE ADDUCT CHEMISTRY

ARADUR 3987 belongs to the modified polyamine-adduct family. Polyamine adducts are produced by partially reacting amine functionality with suitable reactive compounds before the curing agent is supplied for final use. This pre-reaction modifies molecular size, compatibility, volatility, viscosity, water emulsifiability and cure behavior.
The commercial adduct retains primary and secondary amine hydrogens that can react with epoxy groups. These reactive hydrogens open oxirane rings in the epoxy resin and build the final crosslinked network.

The modified structure is particularly important in waterborne formulation because it must remain compatible with an aqueous phase while still interacting effectively with hydrophobic epoxy resin. The hardener must support emulsification, film formation and chemical cure at the same time.
Because the active material is a distribution of related structures rather than one pure low-molecular-weight compound, functional data such as AHEW, amine value, solids, viscosity and resin compatibility provide a more useful technical description than a single structural formula.

HOW EPOXY CURING WORKS

Epoxy resins contain reactive three-membered oxirane rings. Primary and secondary amine hydrogens in ARADUR 3987 attack these rings, opening them and forming new carbon-nitrogen bonds together with hydroxyl groups.
Repeated reactions between multifunctional epoxy resin and multifunctional amine hardener create a three-dimensional thermoset network. The system changes progressively from a liquid mixture to a higher-viscosity state, then to a gel and finally to a solid crosslinked coating.
The reaction does not stop when the film becomes tack-free. Hardness, chemical resistance, thermal resistance, adhesion and water resistance continue to develop as conversion increases.
In waterborne coatings, physical drying occurs simultaneously. Water must leave the film while the resin phases form a continuous coating and the epoxy-amine reaction proceeds. Final performance therefore depends on both chemistry and film formation.

HIGH SOLIDS CONTENT

ARADUR 3987 is supplied at approximately 79-81% solids in water. This high concentration is one of its most important differences from lower-solids waterborne amine adducts.
With only approximately 19-21% water in the commercial product, the formulation receives substantially less carrier water per unit of reactive hardener than it would with a 40% or 50% solids product.
This can support higher overall formulation solids, lower drying demand and greater dry-film build. It can also reduce the amount of additional water that must evaporate before full coating properties develop.
High solids usually increase viscosity, which explains why ARADUR 3987 is comparatively viscous as supplied despite its aqueous carrier. Formulation water can be adjusted where appropriate, but unnecessary dilution should be avoided if high-solids performance is desired.

WATER CONTENT

The commercial grade contains approximately 19-21% water by difference from its published solids range. This water functions as the carrier for the modified polyamine adduct.
Water does not become part of the principal crosslinked epoxy network. It must leave the film during drying.
The relatively low water fraction is beneficial for coating systems that need fast physical drying or higher film build. Less carrier water also means less volume contraction associated with evaporation.
Additional water can still be used to adjust application viscosity when the complete formulation permits it. The optimum amount depends on resin technology, pigment loading, film thickness and application method.

VISCOSITY

ARADUR 3987 has a published viscosity of approximately 15,000-30,000 mPa·s at 25°C. This is a relatively high viscosity consistent with a concentrated polymeric waterborne curing agent.
Viscosity affects transfer, metering, mixing and final application preparation. Temperature has a strong influence, so quality-control measurements should be performed at the specified temperature.
Cold product can become substantially thicker, while warmer product becomes easier to pump and disperse. Warmer temperature can also accelerate cure after the resin and hardener are mixed.
Where lower application viscosity is required, water or formulation-compatible components can be used according to validated formulation guidance rather than uncontrolled field dilution.

AMINE VALUE

The published amine value of ARADUR 3987 is approximately 200-250 mg KOH/g. This relatively high value is consistent with a concentrated curing agent containing substantial basic amine functionality.
Amine value is useful for batch identification and quality control. Significant deviation can indicate composition drift, contamination or degradation.
Amine value should not be confused with active-hydrogen equivalent weight. Basic nitrogen can contribute to titration behavior even when its reactive-hydrogen contribution differs.
For stoichiometric formulation, AHEW and resin-specific mix ratios are more directly useful.

ACTIVE HYDROGEN EQUIVALENT WEIGHT

ARADUR 3987 has an active-hydrogen equivalent weight of approximately 147 g/eq as supplied. This relatively low AHEW for a waterborne curing agent reflects the high active-solids content.
AHEW represents the mass of commercial curing agent required to supply one equivalent of reactive amine hydrogen. It is therefore central to resin-to-hardener calculations.
The product's published reference ratios demonstrate how resin architecture changes hardener demand. ARALDITE PY 33757 is used at approximately 100:83 parts by weight, while ARALDITE PZ 3961-1 is used at approximately 100:28.
These substantially different ratios show why one universal phr should never be applied across unrelated epoxy resin systems.

DENSITY

The typical density of ARADUR 3987 is approximately 1.1 g/cm³ at 23°C.
Density is useful for manufacturing calculations, inventory control and conversion between weight and volume.
Mix ratios should normally be controlled on a mass basis because resin and hardener densities differ. Volumetric systems should be calibrated using actual density data.
A large unexpected density change can indicate concentration variation or contamination, although solids, viscosity and amine value provide more direct composition controls.

FLASH POINT

The published closed-cup flash point is greater than approximately 100°C.
This relatively high value is consistent with a waterborne hardener rather than a conventional solvent-cut amine solution.
The organic curing-agent fraction can nevertheless decompose or burn under severe heating. Fire safety should therefore follow the current product SDS.
Combustion or thermal decomposition can produce carbon monoxide, carbon dioxide, nitrogen oxides and other toxic gases or vapors.

HIGH REACTIVITY

High reactivity is one of the defining characteristics of ARADUR 3987. The product provides short curing times whether the resin component is based on a solid or liquid epoxy resin.
This is important because some waterborne curing agents perform rapidly with liquid epoxy resin but much more slowly when used with solid resin dispersions. ARADUR 3987 is designed to retain high reactivity across both resin forms.
Selector literature gives an approximate gel-time value of 60 minutes under its standardized comparison conditions.
Practical working time remains formulation-specific. Pigments, fillers, water level, temperature and batch size can all change cure behavior.

CHEMICAL RESISTANCE

High chemical resistance is explicitly identified.
Chemical resistance develops from the crosslinked epoxy network after sufficient cure. Resin chemistry, hardener ratio and degree of conversion all influence the final resistance profile.
Liquid bisphenol-A epoxy, modified epoxy and solid epoxy dispersion systems can produce different resistance even when cured with the same ARADUR 3987.
The actual formulation should therefore be tested against the intended chemical, concentration, temperature and contact time.

THERMAL RESISTANCE

High thermal resistance is another key product feature identified.
Thermal performance depends on crosslink density, resin rigidity and cure completeness. A highly reactive curing agent can support strong network development when the stoichiometry and cure conditions are appropriate.
Glass-transition temperature and mechanical-property retention should be measured after the final cure schedule if the coating or composite will see elevated temperature.
Thermal resistance should not be interpreted as unlimited heat resistance. The final system must be qualified for its continuous and peak service temperatures.

GEL TIME

The literature lists an approximate 60-minute gel time for ARADUR 3987 under its standardized comparison method.
Gel time is useful for comparing curing agents under common conditions but should not be confused directly with field pot life.
A coating can lose ideal sprayability, flow or leveling before reaching formal gelation. Thin films can also cure differently from bulk material because water evaporation and heat dissipation change reaction conditions.
Practical application time should therefore be established using the final resin, pigment package, temperature and film thickness.

COLOR

ARADUR 3987 has a Gardner color limit of approximately 8.
This moderate color is acceptable for many primers, industrial coatings and pigmented systems.
In clear or very pale formulations, hardener color can contribute to the initial tone of the film. Resin color, pigments and aging also influence appearance.
Outdoor UV exposure can cause epoxy yellowing or chalking independently of hardener color, so weatherability must be assessed for the complete coating.

BENZYL-ALCOHOL-FREE CHARACTER

 ARADUR 3987 is benzyl-alcohol-free.
Benzyl alcohol is commonly used in some amine hardeners as a viscosity reducer, accelerator or formulation aid. Eliminating it can support lower migration and simpler waterborne formulation.
The absence of benzyl alcohol does not mean the product contains no carrier because ARADUR 3987 is supplied in water.
Formal restricted-substance claims should always be supported by current supplier documentation when required.

APPLICATIONS

Waterborne coatings
ARADUR 3987 is designed primarily for water-based epoxy coatings and layers on mineral and metallic substrates. Its high solids, reactivity and broad resin compatibility allow use across multiple waterborne coating architectures.

Industrial maintenance coatings
Industrial steel, machinery and process equipment can use ARADUR 3987-based epoxy systems where chemical resistance and reduced solvent use are required. The complete coating stack should be selected for the actual exposure severity.

Civil-engineering coatings
Literature associates ARADUR 3987 with civil-engineering applications. Concrete primers, sealers, protective layers and mineral-surface coatings are relevant where the resin system is compatible.

Marine coatings
Selector literature also maps ARADUR 3987 into marine-coating application categories. Salt contamination, immersion conditions and final topcoat design must be considered carefully.

Metal coatings
ARADUR 3987 can be used on metallic substrates with compatible resin and pigment technology. Proper steel cleaning and surface profile remain essential.

Mineral coatings
Concrete, masonry and other mineral substrates can be coated with ARADUR 3987-based systems where moisture, porosity and surface strength are acceptable.

Anti-corrosion primers
ARADUR 3987 can be used in waterborne epoxy primers containing suitable corrosion-inhibitive pigments and barrier extenders. Corrosion resistance depends on the complete formulation rather than the hardener alone.

Direct-to-metal coatings
The grade can be evaluated in DTM systems where the coating must provide both adhesion and protective barrier performance. Pigment selection and film continuity are critical.

Concrete primers
High reactivity and aqueous formulation make ARADUR 3987 suitable for compatible concrete primer technology. Substrate moisture and laitance should be controlled.

Concrete protective coatings
Mineral surfaces exposed to cleaning, water or industrial chemicals can use appropriate ARADUR 3987 epoxy coatings after complete formulation validation.

Floor coatings
Waterborne epoxy floor systems can use ARADUR 3987 where high reactivity and chemical resistance are desired. Aggregate or filler can be incorporated for mechanical durability.

Industrial flooring
Factories, workshops and warehouses can use compatible ARADUR 3987 systems where low solvent emission and robust cure are required.

Warehouse floors
Waterborne epoxy floors can provide cleanability and resistance to oils and dirt. Traffic should begin only after adequate cure.

Workshop floors
Workshops can use high-reactivity waterborne epoxy flooring where resistance to cleaning agents and oils is required.

Plant-room coatings
Utility rooms, service corridors and process areas can benefit from waterborne epoxy coatings with reduced conventional solvent odor.

Protective wall coatings
Mineral walls in industrial or institutional settings can use waterborne epoxy where cleanability and chemical resistance are needed.

Liquid-epoxy coatings
ARADUR 3987 is compatible with liquid epoxy resins such as ARALDITE GY 776 according to TDS information.

Liquid-resin-emulsion coatings
The grade can be used with liquid resin emulsions such as ARALDITE PZ 33757-67, allowing fully waterborne two-component coating design.

Solid type-1 resin dispersion coatings
ARADUR 3987 is compatible with solid type-1 resin dispersions such as ARALDITE PZ 3961-1. This is an important feature because solid resin dispersions require both coalescence and chemical cure.

High-solids waterborne coatings
Approximately 80% curing-agent solids support coating designs that reduce carrier-water load compared with more dilute hardeners.

Fast-cure waterborne coatings
High reactivity allows shorter curing times when application conditions and resin technology are suitable.

Chemical-resistant coatings
High chemical resistance makes the grade useful for industrial coatings exposed to oils, salts and compatible process chemicals.

Thermally resistant coatings
High thermal resistance allows consideration in coatings that experience elevated service temperatures within the validated range of the full system.

Primer-sealers
Low- to medium-build waterborne primer-sealers can be formulated for mineral surfaces where adhesion and film continuity are important.

Barrier coatings
Epoxy binder systems can create a dense protective layer that slows penetration of water and chemicals. Fillers can further improve barrier performance.

Structural-steel primers
Prepared steel can use ARADUR 3987 waterborne primer technology where corrosion protection and fast cure are required.

Machinery primers
Industrial machinery and fabricated equipment can use compatible waterborne epoxy primers under suitable topcoats.

Pipe coatings
Prepared pipes can use ARADUR 3987 systems for atmospheric and selected industrial exposure. Immersion requires separate qualification.

Tank exteriors
Exterior tank surfaces can use waterborne epoxy primers beneath UV-resistant finish coats.

Container coatings
Fabricated steel transport containers can use high-reactivity waterborne primer technology where line speed and corrosion protection are important.

Marine maintenance primers
The grade can be evaluated for maintenance of marine steel where substrate preparation and environmental drying conditions are controlled.

Coastal infrastructure coatings
Waterborne epoxy systems can be used in coastal environments when salt contamination is removed and the full primer/topcoat system is qualified.

Bridge-maintenance coatings
ARADUR 3987 can be considered in low-VOC epoxy primer systems for bridge steel, subject to required corrosion testing.

Factory-applied coatings
Controlled airflow and temperature in factories can maximize the fast-cure benefit of ARADUR 3987.

Low-odor industrial coatings
Waterborne delivery reduces the conventional solvent odor associated with aromatic-solvent curing-agent solutions.

High-build primers
High-solids resin/hardener combinations can be formulated for higher film build where sag and water release are controlled.

Pigmented epoxy primers
Titanium dioxide, iron oxides and extenders can be incorporated into compatible ARADUR 3987 coating systems.

Zinc-phosphate primers
Corrosion-inhibitive pigments such as zinc phosphate can supplement epoxy barrier performance when compatible with the aqueous system.

Lamellar-pigment primers
Mica and micaceous iron oxide can increase diffusion path length and improve barrier protection.

Clear sealers
Clear or lightly pigmented waterborne epoxy sealers can be formulated for mineral surfaces where the color and haze of the complete system remain acceptable.

Adhesion-promoting primers
ARADUR 3987 can support primer systems intended to create strong bonding between a prepared substrate and subsequent coating layers.

Waterborne epoxy adhesives
The grade can be evaluated in compatible aqueous epoxy adhesive systems where water can leave the bond line and the cure profile is appropriate.

Mineral bonding
Concrete, stone and related surfaces can be bonded or sealed with suitable ARADUR 3987 epoxy technology where substrate moisture is controlled.

Repair compounds
Filled epoxy repair formulations can use ARADUR 3987 where high reactivity and waterborne processing are desired.

Mortar-type systems
Mineral-filled binder systems can be developed where the resin/hardener combination wets filler effectively and cure-through is validated.

Protective floor primers
Waterborne primers under thicker flooring systems can use ARADUR 3987 to provide adhesion and chemical bonding to the substrate.

Multi-coat epoxy systems
The hardener can be used in primer or intermediate layers beneath compatible waterborne or solvent-borne topcoats.

Interior protective coatings
Low conventional solvent content makes waterborne ARADUR 3987 systems attractive for enclosed industrial areas.

Maintenance coatings for occupied facilities
Reduced solvent odor can simplify application in facilities that cannot tolerate strong solvent emissions, provided adequate ventilation is maintained.

Industrial concrete sealers
Concrete surfaces requiring improved chemical resistance and cleanability can use compatible ARADUR 3987 binder technology.

Chemical-processing areas
Coatings used around process equipment can exploit the grade's high chemical resistance where the exact exposure has been tested.

Heat-exposed industrial areas
High thermal resistance can be useful around machinery or process equipment that generates moderate heat, subject to final-system qualification.

ARALDITE PY 33757 MIX RATIO

TDS information gives an optimum mix ratio of approximately 100 parts ARALDITE PY 33757 to 83 parts ARADUR 3987 by weight.
This ratio is specific to the commercial resin and curing-agent pair. It should not be treated as a universal hardener level for every liquid epoxy resin.
TDS also states that use of only approximately 80% of the recommended hardener amount can be preferable depending on application and required properties.
For the 83-part reference value, 80% corresponds to roughly 66 parts hardener per 100 parts resin. Such adjustment should be validated for cure, adhesion, chemical resistance and water resistance rather than adopted automatically.

ARALDITE PZ 3961-1 MIX RATIO

TDS information gives an optimum mix ratio of approximately 100 parts ARALDITE PZ 3961-1 to 28 parts ARADUR 3987 by weight.
The much lower hardener level compared with PY 33757 demonstrates the importance of resin-specific formulation.
PZ 3961-1 is a solid type-1 epoxy resin dispersion and has a very different epoxy equivalent and solids structure from a water-dilutable liquid resin.
Physical film formation also differs because solid resin particles must coalesce as water evaporates. ARADUR 3987 is specifically compatible with this resin technology.

ARALDITE GY 776 COMPATIBILITY

 ARALDITE GY 776 is a suitable liquid epoxy resin for ARADUR 3987 waterborne coatings.
A liquid resin can provide efficient film formation because the epoxy phase does not depend entirely on fusion of solid resin particles.
The exact resin-to-hardener ratio should follow current GY 776 and ARADUR 3987 formulation guidance rather than being copied from PY 33757.
Water level and emulsification method should also be optimized for stable mixing and final film quality.

ARALDITE PZ 33757-67 COMPATIBILITY

ARADUR 3987 can also be used with liquid resin emulsions such as ARALDITE PZ 33757-67.
A pre-emulsified liquid resin simplifies waterborne formulation because the resin is already dispersed in the aqueous phase.
Emulsion stability, pigment compatibility and cure should be evaluated after hardener addition.
The resin-specific mix ratio should be obtained from current technical data rather than inferred from another PZ or PY grade.

LIQUID EPOXY RESINS

ARADUR 3987 can be formulated with compatible liquid epoxy resins.
Liquid epoxy systems often need controlled emulsification or surfactant support to remain dispersed in the aqueous phase after mixing.
Resin EEW controls theoretical hardener demand, while viscosity and hydrophobicity affect emulsion stability.
The final system should be tested for pot life, flow, gloss, adhesion, chemical resistance and water resistance.

LIQUID RESIN EMULSIONS

Liquid resin emulsions contain droplets of liquid epoxy dispersed in water.
These systems can provide good film formation because the resin is already fluid when water evaporates.
ARADUR 3987 can cure these emulsified resins while providing high reactivity and chemical resistance.
Surfactant level should be minimized to the amount needed for stability because excess surfactant can increase final water sensitivity.

SOLID TYPE-1 EPOXY DISPERSIONS

Solid type-1 epoxy dispersions contain particles of preformed solid epoxy resin dispersed in water.
As water evaporates, the particles must coalesce into a continuous phase while the amine hardener reacts with epoxy groups.
ARADUR 3987 is specifically compatible with PZ 3961-1 and therefore supports this combined physical and chemical process.
Application temperature, humidity and film thickness influence coalescence and should remain within validated ranges.

WHY RESIN TYPE MATTERS

The large difference between the 83-part PY 33757 ratio and the 28-part PZ 3961-1 ratio demonstrates that waterborne resin form has major consequences for formulation.
The commercial resin may contain different solids, EEW, emulsifier level and particle morphology.
Chemical stoichiometry is therefore only one part of formulation design. Physical film formation and water removal are equally important.
Every resin-hardener combination should be treated as its own coating system.

REDUCED HARDENER LEVEL

 TDS information states that approximately 80% of the recommended hardener amount may be preferable depending on application and required properties.
Reducing hardener shifts the network toward a more epoxy-rich composition and can change hardness, chemical resistance, flexibility, adhesion and water sensitivity.
The optimum direction depends on resin and service requirement.
Any reduced-hardener formulation should therefore be tested for cure completeness and long-term durability.

POT LIFE MANAGEMENT

High reactivity means mixed ARADUR 3987 systems should be processed within their validated working period.
Warmer temperature accelerates epoxy-amine reaction and can shorten pot life substantially.
Large mixed batches can self-heat because the reaction is exothermic, further reducing working time.
Only the amount that can be applied reliably should be mixed, and elapsed time should be recorded from the moment resin and hardener are combined.

FILM FORMATION

Waterborne epoxy performance depends on continuous film formation as water evaporates.
Liquid resin systems and solid resin dispersions reach this state through different physical mechanisms, but both ultimately require a uniform crosslinked epoxy phase.
Poor film formation can produce haze, porosity, weak adhesion and low chemical resistance even when cure chemistry is active.
Resin technology, temperature, water content and additive selection should therefore be optimized as a system.

DRYING AND VENTILATION

The high solids of ARADUR 3987 reduce the water introduced by the hardener, but the complete formulation still contains water from resin dispersions and additional dilution.
Adequate ventilation maintains the evaporation driving force and prevents the air above the film from becoming saturated.
High humidity and stagnant air slow drying.
Factory or field application procedures should therefore control airflow without creating excessive dry spray, surface skinning or dust contamination.

LOW-TEMPERATURE APPLICATION

Low temperature increases viscosity and slows both water evaporation and epoxy reaction.
ARADUR 3987's high reactivity can help, but the final system should still be tested at the minimum intended application temperature.
Cold steel or concrete can also fall below the dew point, causing condensation and adhesion failure.
Substrate temperature is therefore as important as air temperature.

HIGH-HUMIDITY APPLICATION

High humidity reduces the rate at which water can leave a coating.
The high solids of ARADUR 3987 reduce the amount of carrier water contributed by the hardener, which can be advantageous under humid conditions.
Nevertheless, total formulation water and airflow still control physical drying.
Early coating performance should be validated at realistic humidity when the product will be used in damp climates or enclosed areas.

PIGMENT COMPATIBILITY

ARADUR 3987 can be used in pigmented industrial, marine and civil-engineering coatings.
Pigment surfaces can adsorb dispersant or amine and can change pH, ionic strength and viscosity.
Titanium dioxide, iron oxides, zinc phosphate, barytes, talc, mica and silica are examples of materials that may be evaluated in compatible formulations.
The complete pigment grind should be checked after hardener addition because stability on the resin side alone does not guarantee final-system stability.

ANTI-CORROSIVE PIGMENTS

Anti-corrosive pigments can supplement the barrier protection provided by the cured epoxy binder.
Zinc phosphate and related inhibitive pigments can improve corrosion resistance at defects.
Lamellar fillers such as micaceous iron oxide can increase the diffusion path for water and oxygen.
Pigment volume should be optimized so that protective function is improved without making the film excessively porous.

RHEOLOGY CONTROL

ARADUR 3987 is relatively viscous, but final coating rheology depends strongly on resin, water level, pigment loading and additives.
Vertical coatings need low-shear structure to resist sag, while spray application needs shear thinning.
Associative thickeners, clays, cellulose derivatives or other rheology technologies can be used where compatible.
Rheology should be checked after the complete two-component system is mixed because amine addition can change pH and thickener efficiency.

DEFOAMING

Waterborne mixing can introduce foam and entrained air.
Persistent bubbles can create pinholes that reduce chemical and corrosion resistance.
Suitable defoamers can improve air release, but excessive defoamer can cause craters or reduce intercoat adhesion.
Defoamer selection should therefore be evaluated alongside appearance and protective performance.

WATER DILUTION

Additional water can be used where required to adjust application viscosity.
The amount should be controlled because excessive water lowers wet-film solids and increases drying time.
High dilution can also increase sag, reduce film build and delay early water resistance.
Deionized water is generally preferred where dissolved salts could affect corrosion performance or dispersion stability.

ORDER OF ADDITION

The order of addition can affect stability, foam, viscosity and pot life.
Pigment grind is often prepared on the resin side before final hardener addition so that high-shear dispersion does not occur in the fully reactive system.
ARADUR 3987 should be incorporated under sufficient agitation to achieve uniform distribution.
Production instructions should standardize mixing time and sequence rather than allowing uncontrolled variation between batches.

SURFACE PREPARATION

Metal substrates should be free from oil, grease, salts, rust and loose scale.
Abrasive blasting is often preferred for demanding anti-corrosion service because it provides both cleanliness and profile.
Concrete and mineral surfaces should be sound, clean and free from weak laitance, dust and curing compounds.
Good wetting and reactive chemistry cannot compensate fully for contamination or mechanically weak substrate.

FLASH RUST CONTROL

Waterborne primers can cause flash rust on reactive steel if drying is too slow or inhibition is inadequate.
High solids and high reactivity can help reduce the wet period, but formulation still needs appropriate pigment and inhibitor design.
Water quality and dissolved salts can influence early corrosion.
Flash-rust behavior should be evaluated on the actual substrate under the intended humidity and drying conditions.

ADHESION

Epoxy chemistry provides strong adhesion to many properly prepared substrates.
ARADUR 3987's high reactivity can rapidly develop network strength after application.
Metal adhesion depends on surface cleanliness and profile, while concrete adhesion depends on substrate strength and removal of laitance.
Pull-off, cross-cut or other adhesion tests should be selected according to the application.

WATER RESISTANCE

Water resistance improves as carrier water leaves and crosslinking progresses.
Early exposure to liquid water can produce whitening or softness before the coating reaches full cure.
The final network can provide strong water resistance when resin, hardener ratio and film formation are optimized.
Water immersion should be tested separately from atmospheric humidity exposure.

CHEMICAL-RESISTANCE TESTING

High chemical resistance is a key ARADUR 3987 attribute, but the exact resistance profile belongs to the complete formulation.
Testing should use actual service chemicals at the intended concentration and temperature.
Immersion, splash and vapor exposure can produce different results.
Hardness retention, swelling, discoloration, blistering and adhesion should all be considered during evaluation.

THERMAL-PERFORMANCE TESTING

High thermal resistance should be validated through measurements appropriate to the intended service.
Glass-transition temperature, heat resistance and modulus retention can be assessed after full cure.
Post-cure can increase conversion in some epoxy systems, but waterborne coatings are often designed for ambient cure, so the practical process must be considered.
The resin architecture strongly influences maximum thermal performance.

RECOATABILITY

ARADUR 3987 coatings should be recoated within a validated interval.
A subsequent coat applied while the first layer retains chemical reactivity can achieve strong intercoat bonding.
After full cure, abrasion or cleaning may be required depending on surface condition and topcoat chemistry.
Amine blush, dust and soluble contamination should be removed before recoating.

AMINE BLUSH

Amine-cured epoxies can form surface deposits when reactive amines interact with moisture and carbon dioxide.
Waterborne adduct chemistry can reduce some free-amine effects but does not eliminate the mechanism completely.
Blush can interfere with gloss and intercoat adhesion.
Any visible or suspected deposit should be removed according to the coating procedure before applying another layer.

WEATHERING

Conventional epoxy chemistry can chalk and lose gloss under prolonged ultraviolet exposure.
ARADUR 3987's thermal and chemical resistance do not automatically provide long-term decorative weatherability.
Exterior systems often use epoxy as primer or intermediate layer beneath a UV-resistant polyurethane, acrylic or polysiloxane topcoat.
Weathering should therefore be evaluated according to the complete coating architecture.

QUALITY CONTROL

Important quality-control parameters include appearance, Gardner color, amine value, viscosity, solids content and density.
The material should remain a clear liquid without abnormal phase separation or contamination.
Amine value verifies chemical functionality, viscosity supports handling consistency and solids confirm concentration.
Functional cure testing with a standardized epoxy resin can provide an additional application-level quality check.

WHY SOLIDS CONTENT MATTERS

High solids are central to ARADUR 3987's formulation value.
If solids fall below specification, the same wet hardener mass introduces more water and less reactive material.
This can alter mix ratio, drying time and final properties.
If solids increase, viscosity and reactive concentration rise. Consistent concentration therefore supports both processing and cure control.

WHY AHEW MATTERS

AHEW connects hardener mass to reactive hydrogen equivalents.
ARADUR 3987's approximately 147 g/eq value is relatively low for a waterborne curing agent because the product is highly concentrated.
The value applies to the commercial product as supplied.
Using an incorrect AHEW or copying a ratio from another ARADUR grade can cause major stoichiometric error.

WHY GEL TIME MATTERS

The approximately 60-minute selector gel time demonstrates the product's high reactivity under standardized conditions.
Gel time helps compare curing agents, but practical pot life depends on resin, temperature, water and formulation.
A coating can become unsuitable for spray or leveling before formal gelation.
Field and production procedures should therefore define a validated maximum working time.

TDS, SDS AND COA

The current Technical Data Sheet or official product documentation should be used to confirm specification values, mix ratios, storage conditions and application guidance.
The Safety Data Sheet governs composition disclosure, hazard classification, first aid, firefighting, transport, handling and disposal.
The Certificate of Analysis provides batch-specific controlled values where supplied.
Historical  literature is technically useful but should not replace current supplier documents where formal regulatory or specification decisions are required.

SAFETY AND HANDLING

ARADUR 3987 is a reactive amine curing agent and should be handled according to the current SDS.
Waterborne form and high flash point reduce conventional solvent exposure but do not eliminate hazards associated with reactive amine chemistry.
Appropriate chemical-resistant gloves, eye protection and protective clothing should be used.
Ventilation should be suitable for the complete coating system and application method, particularly during spray application.

FIRST AID

After skin contact, contaminated skin should be washed promptly according to the current SDS and contaminated clothing should be removed where appropriate.
If product enters the eyes, immediate and prolonged rinsing with clean water should begin and medical attention should be obtained according to SDS guidance.
If mist or aerosol is inhaled and symptoms occur, move the affected person to fresh air and obtain appropriate medical advice.
After accidental ingestion, follow current SDS and professional medical guidance.

SPILL MANAGEMENT

Spilled ARADUR 3987 can create a slippery surface and should be contained promptly.
Personnel should use the protective equipment specified by the SDS.
Recovered material and contaminated absorbent should be placed in suitable labeled waste containers.
Uncontrolled discharge to drains, soil or surface water should be prevented.

FIRE RESPONSE

The product contains substantial water and has a flash point above approximately 100°C, reducing conventional flammability relative to solvent-cut hardeners.
The organic amine-adduct fraction can nevertheless burn or decompose when strongly heated. identifies carbon monoxide, carbon dioxide, nitrogen oxides and other toxic gases and vapors as possible fire-decomposition products.
Fire response should follow the current SDS and facility emergency procedures.

STORAGE

TDS information recommends storing ARADUR 3987 in a dry place, preferably in the sealed original container, at approximately 2-40°C.
The product should be protected from direct sunlight.
TDS also instructs users to stir ARADUR 3987 before use.
Historical product literature gives a shelf life of approximately one year under the stated conditions, with the expiry date on the original container controlling. Current supplier documentation should govern present shelf-life decisions.

STIR BEFORE USE

Stirring before use helps ensure that the commercial aqueous hardener is uniform after storage.
Even a visually clear product can develop small concentration gradients during extended storage.
Gentle but thorough mixing is preferred to excessive high-speed agitation that could introduce foam.
Uniformity is especially important before metering because water and active hardener must remain at the intended concentration.

REGULATORY CONSIDERATIONS

ARADUR 3987 is a proprietary industrial mixture and regulatory status depends on its complete current composition and jurisdiction.
Historical selector literature associated ARADUR 3987 with food-compliant waterborne systems under then-applicable EU legislation, but such historical statements should not be used as present regulatory approval without current confirmation.
Food-contact, potable-water, medical or other specialized uses require current application-specific documentation for the full coating system.
Current REACH, TSCA and regional inventory status should therefore be obtained from up-to-date supplier documentation when formal compliance is required.

ENVIRONMENTAL CONSIDERATIONS

Waterborne high-solids curing-agent technology can reduce conventional organic-solvent emissions.
Uncured amine-containing material should nevertheless not be released directly into soil, drains or surface water.
Cleaning water can contain reactive resin, hardener, pigments and additives and should be managed as process waste under applicable rules.
Fully cured epoxy has different mobility and reactivity from uncured components, but disposal requirements remain jurisdiction-specific.

COMMON FORMULATION PROBLEMS

Pot life shorter than expected
High material temperature, large batch size, reactive pigments or a more reactive resin can shorten working time. Standardize temperature and batch size before changing chemistry.

Slow drying
High humidity, poor airflow, low substrate temperature or excessive water dilution can slow physical drying. Improve ventilation and control added water.

Poor film formation
An unsuitable resin-hardener combination or low temperature can prevent proper coalescence. Use validated resin technology and maintain adequate film-forming conditions.

Poor adhesion
Oil, salts, rust, dust, weak concrete laitance or condensation can create a weak boundary layer. Correct substrate preparation before changing the hardener.

Poor corrosion resistance
Low film thickness, porosity, poor metal preparation or an unsuitable pigment package can reduce protection. Evaluate the complete primer system.

Flash rust
Slow water loss or inadequate inhibition can allow early corrosion on steel. Optimize drying conditions, pigment package and water quality.

Soft film
Incorrect mix ratio, incomplete cure or retained water can leave the coating soft. Verify stoichiometry and drying conditions.

Excessive viscosity
Cold product, high filler loading or reactive advancement can raise viscosity. Confirm temperature and pot-life age before dilution.

Sagging
Excess water or insufficient rheological structure can reduce vertical hold. Adjust water and rheology modifier.

Foaming
High-speed mixing, surfactant imbalance or porous-substrate outgassing can introduce bubbles. Optimize mixing and defoamer package.

Low chemical resistance
Incomplete cure or unsuitable resin chemistry can reduce resistance. Test the fully cured coating under actual exposure conditions.

Loss of gloss
Poor leveling, foam, rough substrate or late-pot-life application can reduce appearance. Apply within the validated working window.

Phase instability
Incompatible additives, electrolytes or incorrect order of addition can destabilize the aqueous system. Review raw materials and formulation procedure.

FREQUENTLY ASKED QUESTIONS

What is ARADUR 3987?
ARADUR 3987 is a high-solids waterborne modified polyamine-adduct epoxy curing agent.

What is the solids content?
Approximately 79-81% by weight.

How much water does ARADUR 3987 contain?
Approximately 19-21% by difference from the published solids level.

What is the viscosity?
Approximately 15,000-30,000 mPa·s at 25°C.

What is the amine value?
Approximately 200-250 mg KOH/g.

What is the active hydrogen equivalent weight?
Approximately 147 g/eq as supplied.

What is the density?
Approximately 1.1 g/cm³ at 23°C.

What is the flash point?
Greater than approximately 100°C by Pensky-Martens closed-cup testing.

What is the recommended ratio with ARALDITE PY 33757?
Approximately 100 parts ARALDITE PY 33757 to 83 parts ARADUR 3987 by weight.

What is the recommended ratio with ARALDITE PZ 3961-1?
Approximately 100 parts ARALDITE PZ 3961-1 to 28 parts ARADUR 3987 by weight.

Can a reduced hardener amount be used?
Historical guidance states that approximately 80% of the recommended hardener amount can be preferable depending on application and required properties.

Can ARADUR 3987 be used with liquid epoxy resin?
Yes. 

Can ARADUR 3987 be used with liquid resin emulsions?
Yes. 

Can ARADUR 3987 be used with solid epoxy dispersions?
Yes. ARALDITE PZ 3961-1 solid type-1 resin dispersion is specifically identified as compatible.

What are the main performance advantages?
High reactivity, short curing time, high chemical resistance and high thermal resistance.

Which substrates are suitable?
 technical information identifies mineral and metallic substrates.

Is ARADUR 3987 benzyl-alcohol-free?
Yes.  selector literature identifies the grade as benzyl-alcohol-free.

Does ARADUR 3987 have one CAS number?
No single CAS number should be assigned to the complete proprietary commercial mixture without confirmation from the current SDS.

How should ARADUR 3987 be stored?
TDS information recommends dry storage in the sealed original container at approximately 2-40°C, protected from direct sunlight, with stirring before use.

What documents should be checked before use?
Use the current product TDS, SDS and batch-specific quality documentation where available.

FINAL TECHNICAL SUMMARY

ARADUR 3987 is a high-solids waterborne modified polyamine-adduct curing agent developed for epoxy coatings on mineral and metallic substrates. The commercial product is supplied as an approximately 80% solids liquid in water and provides a concentrated alternative to more dilute aqueous amine hardeners.
 technical data specify approximately 15,000-30,000 mPa·s viscosity at 25°C, 200-250 mg KOH/g amine value, approximately 147 g/eq active-hydrogen equivalent weight, about 1.1 g/cm³ density and a flash point greater than approximately 100°C.
The product is distinguished by high reactivity, high chemical resistance and high thermal resistance. 

ARADUR 3987 is unusually versatile in resin compatibility. It can be used with liquid epoxy resins such as ARALDITE GY 776, liquid-resin emulsions such as PZ 33757-67 and solid type-1 resin dispersions such as PZ 3961-1.
Published mix-ratio guidance gives approximately 100:83 parts by weight for ARALDITE PY 33757 / ARADUR 3987 and approximately 100:28 for ARALDITE PZ 3961-1 / ARADUR 3987.
The large difference between those ratios demonstrates why hardener phr must always be tied to the exact resin. A universal wet-weight ratio is technically inappropriate across different liquid and dispersed epoxy systems.

Historical guidance also notes that approximately 80% of the recommended hardener amount may be preferable depending on application and required properties. Any such adjustment should be validated experimentally.  selector literature gives an approximate 60-minute comparative gel time. Practical pot life can differ because resin type, temperature, water content, batch mass, pigments and fillers alter reaction kinetics.

The high 79-81% solids level reduces the amount of carrier water introduced by the curing agent. This can support higher formulation solids, greater film build and reduced drying demand compared with more dilute waterborne hardeners.
Civil-engineering, industrial-maintenance and marine-coating applications are represented in selector literature. Relevant systems include anti-corrosion primers, metal coatings, mineral-substrate coatings, concrete primers, floors, barriers and industrial protective layers.
Chemical resistance should always be validated using the complete formulation because resin chemistry and cure completeness strongly influence final performance. The same applies to thermal resistance.

ARADUR 3987 is identified as benzyl-alcohol-free in selector literature. This supports waterborne formulation without reliance on benzyl alcohol as a viscosity or cure modifier.
Waterborne film formation still requires control of temperature, humidity and airflow. High hardener solids reduce water load but do not eliminate the need for adequate drying.
Surface preparation remains essential. Steel must be clean and appropriately profiled, while concrete must be sound and free from laitance, dust, oil and incompatible curing compounds.
Quality control should focus on appearance, color, viscosity, amine value, solids, density and functional cure behavior. Current supplier documentation should take precedence over historical specifications where any difference exists.

ARADUR 3987 is a proprietary commercial mixture and should not be assigned an invented fixed molecular formula, molecular weight, CAS number or EC number. The current SDS should govern formal identity and hazard classification.
Historical TDS information recommends storage at approximately 2-40°C in sealed original packaging, away from direct sunlight, and instructs users to stir before use. Historical shelf life was listed as approximately one year, subject to the expiry date on the original container.
For ARADUR 3987 technical specifications, application guidance, TDS, SDS, COA and formulation information, contact ATAMAN KIMYA with the intended epoxy resin, substrate, coating type, application method and required chemical or thermal performance.

ATAMAN KIMYA
Phone: +90 216 577 10 10
Email: info@atamankimya.com