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Hydrophilic (untreated) Fumed Silica is used in coatings and paints to improve the free flow of powders, prevent sedimentation, and thicken.
Hydrophilic (untreated) Fumed Silica is used in cosmetics for its light-diffusing properties.
Hydrophilic (untreated) Fumed Silica is used as a light abrasive, in products like toothpaste.
CAS Number: 112945-52-5 (also used: 7631-86-9 for SiO₂)
EC Number: 231-545-4
General Formula: SiO₂
Molecular weight: 60.0835 g/mol
SYNONYMS:
Fumed Silica, Pyrogenic Silica, Amorphous Silicon Dioxide, Synthetic Amorphous Silica, Silicon Dioxide (fumed), Aerosil (hydrophilic grades), Cab-O-Sil (hydrophilic grades), Colloidal Silicon Dioxide, Fumed Amorphous Silica, Pyrogenic Amorphous Silica, Silicon(IV) oxide, Synthetic Fumed Silica, Colloidal Amorphous Silica, HDK N20 (Wacker), SpectrA-Sil, Silica Colloidal Anhydrous, Silica Amorphous Fumed, SiO₂ (amorphous), Hydrophilic Colloidal Silica, Non-treated Fumed Silica, Untreated Synthetic Silica, Silica, Silicon Dioxide, Pyrogenic Silica, Synthetic Amorphous Silica, Aerosil, Cab‑O‑Sil, Orisil, Fumed Silicon Dioxide, Silicon(IV) Oxide, Silica Gel, Silicic Anhydride
Hydrophilic (untreated) Fumed Silica is a nanomaterial with strong hygroscopicity (absorbing moisture).
This fluffy white powder, Hydrophilic (untreated) Fumed Silica, is based on high purity amorphous silica.
Hydrophilic (untreated) Fumed Silica can be wetted by water, and dispersed in water forming a suspension.
When Hydrophilic (untreated) Fumed Silica is first produced from oxyhydrogen flame, the moisture content is very low.
Hydrophilic (untreated) Fumed Silica, or pyrogenic silica, is an ultrafine, amorphous powder produced through a specialized chemical process.
It’s recognized for Hydrophilic (untreated) Fumed Silica's significant surface area and unique ability to modify the properties of various products.
There are various grades of Hydrophilic (untreated) Fumed Silica, which are defined by their amorphous structure.
Hydrophilic (untreated) Fumed Silica is used to provide thixotropic properties in coatings and adhesives.
Hydrophilic (untreated) Fumed Silica also assists in enhancing flow in the production industry, such as cosmetics and pharmaceuticals.
Hydrophilic (untreated) Fumed Silica is a highly versatile nano-scale amorphous SiO₂ powder used across industries for thickening, anti-caking, moisture control, and reinforcement.
Hydrophilic (untreated) Fumed Silica is safe when properly handled with dust precautions, and its functional profile—high surface area, stability, and thixotropy—makes it indispensable in coatings, personal care, food, pharmaceuticals, and advanced materials.
Hydrophilic (untreated) Fumed Silica or pyrogenic silica is a multi-purpose silica-based additive commonly used to manipulate viscosity, rheology and enhance functionality of existing polymer matrices.
Hydrophilic (untreated) Fumed Silica has a low particle size and low bulk density, meaning the surface area is very high.
Hydrophilic (untreated) Fumed Silicais known for its film and cured adhesives strengthening, sag resistance and anti-settling properties.
When silicon tetrachloride is heated in an aerobic environment at temperatures above 1500°, silicon dioxide is formed.
With increasing heat and pressure, this silicon dioxide combines and combines with itelf, forming aggregates and then Hydrophilic (untreated) Fumed Silica agglomerates.
The three-dimensional structure of fumed silica increases viscosity.
Fumed silica also exhibits a thixotropic behaviour, particularly when used as a reinforcing filler or thickener.
It is typically classified into treated and untreated categories (hydrophilic and hydrophobic).
Generally, hydrophobic fumed silica is cheaper than hydrophilic.
Hydrophilic (untreated) Fumed Silica commonly exhibits a particle size of around 5–50 nm, bulk density of 160–190 kg/m³, and a surface area of 50–600 m²/g.
What makes Hydrophilic (untreated) Fumed Silica an “invisible helper” is that it typically constitutes only a small fraction of the product (often <2%) and does not alter the product’s appearance or taste.
Hydrophilic (untreated) Fumed Silica works at the micro-level to prevent clumps, maintain smooth texture, and enhance stability.
From the kitchen pantry to the medicine cabinet, Hydrophilic (untreated) Fumed Silica quietly supports the quality and consistency of many consumer goods we use every day.
Hydrophilic (untreated) Fumed Silica (CAS number 7631-86-9, also 112945-52-5), also known as pyrogenic silica because it is produced in a flame, consists of microscopic droplets of amorphous silica fused into branched, chainlike, three-dimensional secondary particles which then agglomerate into tertiary particles.
The resulting powder has an extremely low bulk density and high surface area.
Hydrophilic (untreated) Fumed Silica's three-dimensional structure results in viscosity-increasing, thixotropic behavior when used as a thickener or reinforcing filler.
USES and APPLICATIONS of HYDROPHILIC (UNTREATED) FUMED SILICA:
The Invisible Helper in Consumer Products: From Cosmetics to Food
Hydrophilic (untreated) Fumed Silica often works behind the scenes in everyday consumer products – you might not see it, but it ensures those products perform as intended.
One major use of Hydrophilic (untreated) Fumed Silica is as an anti-caking agent in powders.
Because of its extremely high surface area and adsorptive capacity, Hydrophilic (untreated) Fumed Silica can coat other particles and keep them dry and free-flowing.
In products like spices, powdered drink mixes, and salt shakers, a tiny percentage of silica (labeled as silicon dioxide, food additive E551) prevents clumping by absorbing moisture and separating the grains.
Both Hydrophilic (untreated) Fumed Silica and precipitated amorphous silica are approved for food use, and regulatory authorities (like EFSA in Europe) have confirmed that such silica is safe even in infant food.
Another everyday role is in cosmetics: Hydrophilic (untreated) Fumed Silica is used in makeup powders, where it acts as a light, “invisible” filler that improves texture and flow.
Hydrophilic (untreated) Fumed Silica provides a silky feel, prevents caking in pressed powders, and can scatter light to give a soft-focus effect on the skin.
Hydrophilic (untreated) Fumed Silica's light-diffusing property is valued in high-end cosmetics to blur fine lines (silica microspheres create a diffusive matte look).
Hydrophilic (untreated) Fumed Silica’s oil-absorbing ability also helps control greasiness in creams and lotions without making the product heavy.
In toothpaste, Hydrophilic (untreated) Fumed Silica serves as a gentle abrasive and thickener.
Many modern toothpastes – especially clear gel formulas – use a combination of silica types.
A fine Hydrophilic (untreated) Fumed Silica provides thickening and stabilizes the gel, while larger-particle silica (precipitated silica) provides mild abrasion for cleaning teeth.
The Hydrophilic (untreated) Fumed Silica is crucial in transparent toothpaste because its tiny particle size and refractive index close to water allow the paste to remain clear.
Beyond these, Hydrophilic (untreated) Fumed Silica finds use in pharmaceuticals as a glidant and stabilizer.
Listed in pill formulations as colloidal silicon dioxide, Hydrophilic (untreated) Fumed Silica improves the flow of powder blends during tablet manufacturing.
By reducing inter-particle friction, Hydrophilic (untreated) Fumed Silica enables uniform filling of tablet dies and consistent drug dosages.
Hydrophilic (untreated) Fumed Silica can also act as a moisture scavenger to enhance the shelf life of sensitive formulations.
In personal care products like lotions, hair gels, and deodorants, Hydrophilic (untreated) Fumed Silica contributes to the thickening and suspension of active ingredients.
Even in some food preparations, it appears (for example, a pinch of Hydrophilic (untreated) Fumed Silica can stabilize foam or emulsions in molecular gastronomy).
Hydrophilic (untreated) Fumed Silica is used as a rheological and thixotropic additive for adhesives and sealants.
Hydrophilic (untreated) Fumed Silica is used in coatings and paints to improve the free flow of powders, prevent sedimentation, and thicken.
Applications of Hydrophilic (untreated) Fumed Silica: Coatings & Paintings,
Film & UPR, HTV & RTV Silicon Rubber, Adhesives and Sealants, Printing Ink, Fertilizer, and Cosmetics.
Hydrophilic (untreated) Fumed Silica serves as a universal thickening agent and an anticaking agent (free-flow agent) in powders.
Like silica gel, Hydrophilic (untreated) Fumed Silica serves as a desiccant.
Hydrophilic (untreated) Fumed Silica is used in cosmetics for its light-diffusing properties.
Hydrophilic (untreated) Fumed Silica is used as a light abrasive, in products like toothpaste.
Other uses of Hydrophilic (untreated) Fumed Silica include filler in silicone elastomer and viscosity adjustment in paints, coatings, printing inks, adhesives and unsaturated polyester resins.
Hydrophilic (untreated) Fumed Silica readily forms a network structure within bitumen and enhances its elasticity.
Hydrophilic (untreated) Fumed Silica is commercially used as: Adhesives and sealants strengthened, Anti-caking and thickening agents in powders, Viscosity adjustment in coatings and paint, Desiccants, Cosmetics for its light-diffusing properties, and Toothpaste.
-Hydrophilic (untreated) Fumed Silica in Water-Based Formulations
In Hydrophilic (untreated) Fumed Silica's hydrophilic form, fumed silica serves as a thickening agent, suspending aid, and stabilizer in water-based formulations.
Its high surface area allows Hydrophilic (untreated) Fumed Silica to form a network of particles in liquids, increasing viscosity without significantly altering other properties.
Hydrophilic (untreated) Fumed Silica is particularly valuable in paints, inks, and cosmetic products, where controlled flow and spreadability are desired.
-Sealants and Adhesives: Improving Strength and Durability
Hydrophilic (untreated) Fumed Silica plays an equally critical role in the rheology and reinforcement of sealants and adhesives.
In uncured form, many adhesives and sealant formulations rely on Hydrophilic (untreated) Fumed Silica to adjust viscosity for optimal processing.
As a thixotropic agent, Hydrophilic (untreated) Fumed Silica allows thick products like caulks to be easily extruded or pumped (shear thinning under stress) while preventing them from slumping or running once applied.
For instance, silicone sealants for construction are heavily filled with Hydrophilic (untreated) Fumed Silica, so they hold their shape in a vertical joint and do not sag before curing.
Industry studies confirm that Hydrophilic (untreated) Fumed Silica increases product viscosity, prevents filler settling during storage, controls flow during application, and imparts anti-sag properties during cure.
This ensures that an adhesive bead or sealant line stays exactly where placed, even on overhead or vertical surfaces, until Hydrophilic (untreated) Fumed Silica solidifies.
In addition to rheology control, Hydrophilic (untreated) Fumed Silica also acts as a reinforcing filler in cured adhesives and elastomeric sealants.
The interconnected silica particles become part of Hydrophilic (untreated) Fumed Silica matrix, improving mechanical properties such as tensile strength, tear resistance, and elongation.
For example, in silicone RTV sealants, Hydrophilic (untreated) Fumed Silica is essential to achieve proper hardness and tear strength in the cured rubber; without it, the sealant would be too soft and prone to mechanical failure.
A technical review notes that adding pyrogenic silica not only modifies flow but also improves the physical properties of the cured sealant, especially tear strength and durability under stress.
The silica network reinforces the polymer much like steel rebar in concrete, increasing Hydrophilic (untreated) Fumed Silica’s resistance to crack propagation and deformation.
This translates to a longer service life for sealants and adhesives: they maintain integrity under load, temperature changes, and vibration over time.
In resin-based adhesives, Hydrophilic (untreated) Fumed Silica can also enhance performance by increasing bonding thickness without sacrificing strength – a slightly gelled adhesive can fill gaps better and resist shrinkage.
Furthermore, the presence of silica can improve the thermal stability of the adhesive since SiO₂ itself is heat-resistant.
In summary, silicone sealants, epoxy adhesives, polyurethanes, and many other bonding agents benefit from Hydrophilic (untreated) Fumed Silica as a key additive that provides non-sag application and reinforced cured strength.
Whether in a household caulk or a high-performance industrial adhesive, the inclusion of Hydrophilic (untreated) Fumed Silica leads to a tougher, more reliable bond.
-Applications of Hydrophilic (untreated) Fumed Silica in Coatings: Enhanced Performance and Texture
In the coatings industry, Hydrophilic (untreated) Fumed Silica is prized as a rheology modifier that dramatically improves paint and coating performance.
When dispersed properly, Hydrophilic (untreated) Fumed Silica forms a microscopic network throughout the liquid that increases viscosity at rest and prevents undesirable flow yet allows ease of application under shear.
This yields thixotropic behavior – the coating is gel-like in the can but thins when brushed or sprayed, then quickly recovers viscosity once applied.
As a result, Hydrophilic (untreated) Fumed Silica effectively prevents pigment settling in the can and stops sagging or drips on vertical surfaces during application.
Even at low concentrations, Hydrophilic (untreated) Fumed Silica serves as an “anti-sag” and “anti-settling” agent to ensure uniform film thickness and an even finish.
For example, in high-solids paint formulations that tend to suffer pigment sedimentation and heat-induced sagging, adding a few tenths of a percent of Hydrophilic (untreated) Fumed Silica can solve both problems by imparting robust thixotropy.
Beyond controlling flow, Hydrophilic (untreated) Fumed Silica also enhances the durability and texture of coatings.
Hydrophilic (untreated) Fumed Silica's nano-sized silica network reinforces the dried film, improving properties like scratch and abrasion resistance.
Studies on nanoparticle-filled coatings have found that including Hydrophilic (untreated) Fumed Silica (even ~5–15% by weight) can increase the scratch hardness of a UV-cured polymer coating by 10–35% and significantly raise its resistance to wear.
Hydrophilic (untreated) Fumed Silica effectively hardens the lacquer against scratches and mar, extending the lifetime of the finish.
In clear coatings, well-dispersed pyrogenic silica can be used without compromising transparency since the primary particles are far below visible light wavelengths.
In fact, manufacturers have achieved formulations with improved rheology and maintained optical clarity by using properly dispersed Hydrophilic (untreated) Fumed Silica in varnishes and coatings.
Additionally, Hydrophilic (untreated) Fumed Silica can influence gloss and texture: higher loadings or larger agglomerates will matten a coating (useful for satin or matte finishes), whereas fully dispersed nanosilica can remain gloss-neutral.
In summary, Hydrophilic (untreated) Fumed Silica is a multifunctional additive in paints, inks, and coatings that prevents settling, provides anti-sag stability, and boosts the mechanical robustness of the dried film.
These benefits help coatings not only look better (smooth, uniform, no drips) but also perform better in terms of longevity and protection.
