ALPHA GYPSUM

Alpha Gypsum is the alpha form of calcium sulfate hemihydrate produced under controlled conditions to create dense, well-formed crystals with high strength after setting.
Alpha Gypsum is widely used where fast setting, low porosity, and high compressive strength are required, including precision casting, molds, construction additives, and specialty gypsum products.
Alpha Gypsum is valued for lower water demand than beta hemihydrate, improved mechanical properties, and reliable dimensional stability in hardened applications when properly mixed and cured.

CAS Number: 10034-76-1
EC Number: 231-900-3 (commonly associated; grade dependent)
Molecular Formula: CaSO4·0.5H2O
Molecular Weight: 145.15 g/mol

Synonyms: Alpha Gypsum, Alpha Hemihydrate Gypsum, Alpha Calcium Sulfate Hemihydrate, Calcium Sulfate Hemihydrate (Alpha), α-Hemihydrate Gypsum, α-CaSO4·0.5H2O, High Strength Gypsum, High Strength Plaster, Dental Stone (common category), Casting Gypsum (high strength), Alpha Plaster, Autoclaved Gypsum Hemihydrate, Alpha Gypsum, ALPHA GYPSUM, α-Gypsum, Alpha-gypsum, Alpha Gypsum Hemihydrate, Alpha Hemihydrate Gypsum, Alpha Gypsum Plaster, Alpha Plaster, Alpha Plaster of Paris (common trade wording), Alpha Calcium Sulfate Hemihydrate, Alpha-Calcium Sulfate Hemihydrate, α-Calcium Sulfate Hemihydrate, Calcium Sulfate Hemihydrate (Alpha), α-Hemihydrate, Alpha Hemihydrate, α-Hemihydrate Gypsum, Alpha Hemihydrate Gypsum, Gypsum Hemihydrate (Alpha), Plaster Hemihydrate (Alpha), Alpha Plaster Hemihydrate, High-Strength Gypsum, High Strength Gypsum, High-Strength Plaster, High Strength Plaster, High-Strength Gypsum Plaster, High Strength Gypsum Plaster, High-Strength Plaster of Paris, High Strength Plaster of Paris, α-High Strength Gypsum, Alpha High Strength Gypsum, Alpha High Strength Plaster, Alpha High-Strength Plaster, Alpha Gypsum (high strength), Alpha Gypsum (dense), Dense Gypsum Hemihydrate, Dense Hemihydrate Gypsum, α-Dense Hemihydrate, Alpha Dense Hemihydrate, Alpha Gypsum Stone, Gypsum Stone (Alpha), Dental Stone (Alpha gypsum context), Type III Dental Stone (alpha hemihydrate) (use context), Type IV Dental Stone (alpha hemihydrate) (use context), Type V Dental Stone (alpha hemihydrate) (use context), Model Plaster (alpha hemihydrate) (use context), Casting Plaster (alpha hemihydrate) (use context), Investment Plaster (alpha hemihydrate) (use context), Gypsum Cement (alpha hemihydrate) (use context), Surgical Plaster (alpha hemihydrate) (use context), Orthopedic Plaster (alpha hemihydrate) (use context), Ceramic Plaster (alpha hemihydrate) (use context), Alpha Gypsum Powder, Alpha Gypsum Fine Powder, Alpha Gypsum Granules, Alpha Gypsum High Purity (grade context), Alpha Gypsum Technical Grade

APPLICATIONS

Alpha Gypsum is used in dental stone materials for accurate dental models, dies, and prosthetic fabrication.
Alpha Gypsum is incorporated into dental casting systems to achieve high strength and fine detail reproduction.
Alpha Gypsum is used in orthodontic models where dimensional stability and abrasion resistance are important.

Alpha Gypsum is used in precision mold making for ceramics to create durable molds with good water absorption control.
Alpha Gypsum is incorporated into ceramic casting molds to improve mold strength and service life.
Alpha Gypsum is used in slip casting operations to maintain consistent mold performance and surface finish.

Alpha Gypsum is used in architectural and decorative plasterwork to produce sharp edges and fine surface detail.
Alpha Gypsum is incorporated into ornamental castings to improve strength and reduce breakage during handling.
Alpha Gypsum is used in repair mortars for gypsum-based decorative elements where strong set and low shrinkage are desired.

Alpha Gypsum is used in high-strength gypsum boards and specialty panels to improve mechanical performance.
Alpha Gypsum is incorporated into gypsum-based building components to reduce water demand and enhance strength.
Alpha Gypsum is used in fire-resistant gypsum products where consistent crystal structure supports stable performance.

Alpha Gypsum is used in self-leveling and smoothing compounds as a fast-setting binder in gypsum-based floor systems.
Alpha Gypsum is incorporated into underlayments to improve early strength development and reduce cracking risk.
Alpha Gypsum is used in rapid repair systems where short downtime and quick return to service are required.

Alpha Gypsum is used in casting applications for art and sculpture to produce strong, dense castings with fine detail.
Alpha Gypsum is incorporated into hobby and craft mold systems for repeated use and improved durability.
Alpha Gypsum is used in museum and restoration work for creating accurate replicas and molds.

Alpha Gypsum is used in industrial molds and patterns for foundry and prototyping where dimensional accuracy is critical.
Alpha Gypsum is incorporated into pattern-making materials to improve edge strength and reduce chipping.
Alpha Gypsum is used in tooling casts that require good compressive strength and low porosity.

Alpha Gypsum is used in 3D printing powder-bed binder systems as a mineral base for detailed printed parts.
Alpha Gypsum is incorporated into printing powders to support smooth flow, packing density, and strong green parts.
Alpha Gypsum is used in post-processed printed objects where surface finish and strength are improved by infiltration.

Alpha Gypsum is used in medical and orthopedic casting materials in certain systems where fast set and rigidity are required.
Alpha Gypsum is incorporated into splinting and immobilization products where strength and shape retention are important.
Alpha Gypsum is used in medical training models and anatomical replicas for durable, detailed casting.

Alpha Gypsum is used as a filler and functional mineral in specialty composites where controlled setting is desired.
Alpha Gypsum is incorporated into gypsum cements and formulations for industrial grouting and anchoring in compatible designs.
Alpha Gypsum is valued because Alpha Gypsum provides high-strength, low-porosity set structures and reliable performance across precision casting and construction applications.

Alpha Gypsum is used in high-strength plaster formulations for precise casting applications.
Alpha Gypsum supports production of dense, strong gypsum casts with low porosity.
Alpha Gypsum improves dimensional accuracy in molded plaster parts.

Alpha Gypsum is used in dental stone products for creating accurate dental models and dies.
Alpha Gypsum supports high compressive strength needed for crown and bridge work.
Alpha Gypsum helps produce smooth-surface dental casts with sharp detail reproduction.

Alpha Gypsum is used in orthodontic model production for study casts and aligner workflows.
Alpha Gypsum supports stable, chip-resistant models for repeated handling.
Alpha Gypsum helps maintain accurate occlusion details in dental laboratories.

Alpha Gypsum is used in investment casting molds for jewelry and precision metal casting.
Alpha Gypsum supports fine detail capture in mold making for small components.
Alpha Gypsum helps improve mold strength during burnout and handling.

Alpha Gypsum is used in ceramic mold making to create plaster molds for slip casting.
Alpha Gypsum supports controlled water absorption that helps form ceramic shells.
Alpha Gypsum helps produce consistent mold porosity for repeat casting cycles.

Alpha Gypsum is used in pottery and ceramics for making press molds and hump molds.
Alpha Gypsum supports hard, durable molds that resist abrasion.
Alpha Gypsum helps maintain dimensional stability in repeated forming operations.

Alpha Gypsum is used in construction plasters where higher strength and lower water demand are required.
Alpha Gypsum supports reduced water-to-plaster ratios for denser hardened structures.
Alpha Gypsum helps improve hardness and impact resistance in plaster finishes.

Alpha Gypsum is used in precast gypsum products such as decorative elements and architectural molds.
Alpha Gypsum supports crisp edges and high detail for ornaments and cornices.
Alpha Gypsum helps reduce chipping during demolding and transport.

Alpha Gypsum is used in gypsum-based self-leveling compounds for floors in selected formulations.
Alpha Gypsum supports rapid strength development and smooth surface finish.
Alpha Gypsum helps improve early hardness for faster installation schedules.

Alpha Gypsum is used in repair mortars and patching compounds where fast set and high strength are desired.
Alpha Gypsum supports quick turnaround repairs for walls and ceilings.
Alpha Gypsum helps reduce shrinkage and cracking risk in dense repair patches.

Alpha Gypsum is used in industrial casting of prototypes and models for engineering work.
Alpha Gypsum supports production of accurate pattern parts for design verification.
Alpha Gypsum helps produce smooth surfaces suitable for painting and finishing.

Alpha Gypsum is used in sculpture and art casting for detailed figurines and reliefs.
Alpha Gypsum supports high-resolution reproduction from silicone and rubber molds.
Alpha Gypsum helps improve strength of thin features in art castings.

Alpha Gypsum is used in museum and restoration work for replica creation and molding.
Alpha Gypsum supports faithful replication of fine textures and tool marks.
Alpha Gypsum helps produce durable replicas for handling and display.

Alpha Gypsum is used in theatrical set design for decorative moldings and props.
Alpha Gypsum supports quick fabrication of lightweight decorative components.
Alpha Gypsum helps deliver crisp detail that reads well on stage and on camera.

Alpha Gypsum is used in high-quality chalk and drawing materials in some manufacturing approaches.
Alpha Gypsum supports controlled hardness and smooth marking behavior.
Alpha Gypsum helps produce consistent particle packing in compressed chalk products.

Alpha Gypsum is used in specialty gypsum boards and panels to improve core strength in some designs.
Alpha Gypsum supports improved mechanical performance in gypsum-based building products.
Alpha Gypsum helps reduce breakage during handling of prefabricated elements.

Alpha Gypsum is used in lightweight gypsum composites when blended with fillers and fibers.
Alpha Gypsum supports matrix strength and improved cohesion in composite cores.
Alpha Gypsum helps bind lightweight aggregates for improved structural integrity.

Alpha Gypsum is used in glass-reinforced gypsum products to produce strong decorative panels.
Alpha Gypsum supports improved bonding and strength in reinforced gypsum systems.
Alpha Gypsum helps produce thin, strong architectural panels with detail.

Alpha Gypsum is used in fire-resistant construction products where gypsum hydration water provides fire performance.
Alpha Gypsum supports dense cores that maintain integrity under heat exposure.
Alpha Gypsum helps improve physical performance while maintaining fire resistance benefits.

Alpha Gypsum is used in precision tooling and jigs where a rigid, accurate plaster body is required.
Alpha Gypsum supports stable fixtures for light-duty positioning and alignment tasks.
Alpha Gypsum helps create low-cost tooling for prototyping and workshop use.

Alpha Gypsum is used in mold making for plastics and resins as a support shell around flexible molds.
Alpha Gypsum supports rigid mother-molds that maintain shape during casting.
Alpha Gypsum helps keep silicone molds stable for repeated resin pours.

Alpha Gypsum is used in educational laboratories to demonstrate setting reactions of calcium sulfate hemihydrate.
Alpha Gypsum supports teaching of hydration kinetics and crystal growth.
Alpha Gypsum helps students observe differences between alpha and beta gypsum behavior.

Alpha Gypsum is used in formulation R&D to compare water demand and strength versus beta gypsum.
Alpha Gypsum supports optimizing plaster formulations for target strength and set time.
Alpha Gypsum helps improve reproducibility in plaster product development.

Alpha Gypsum is used in 3D printing binder-jet style gypsum powder systems in some technologies.
Alpha Gypsum supports strong green parts and improved detail in printed components.
Alpha Gypsum helps improve post-processing strength after infiltration in some workflows.

Alpha Gypsum is used in rapid prototyping shops to create castable patterns from digital molds.
Alpha Gypsum supports quick turnaround production of master models.
Alpha Gypsum helps reduce rework by producing accurate cast geometry.

Alpha Gypsum is used in automotive and industrial design for creating form models and surface mockups.
Alpha Gypsum supports sanding and finishing of plaster models for styling work.
Alpha Gypsum helps achieve smooth surfaces for paint and measurement.

Alpha Gypsum is used in foundry pattern making for temporary patterns and core boxes in some cases.
Alpha Gypsum supports accurate pattern surfaces for short-run casting.
Alpha Gypsum helps provide smooth finishes that reduce casting defects.

Alpha Gypsum is used in jewelry prototyping for master models that can be molded for wax injection.
Alpha Gypsum supports high detail and smooth finish for small-scale parts.
Alpha Gypsum helps reduce surface defects transferred into jewelry wax patterns.

Alpha Gypsum is used in decorative wall panels and ceiling medallions for premium finish quality.
Alpha Gypsum supports crisp detail and high hardness in decorative elements.
Alpha Gypsum helps improve durability of installed decorative features.

Alpha Gypsum is used in high-end interior finishing plasters where smoothness and hardness are important.
Alpha Gypsum supports polished plaster effects in certain gypsum-based systems.
Alpha Gypsum helps reduce dusting and improves abrasion resistance after cure.

Alpha Gypsum is used in industrial casting of rubber molds by creating rigid gypsum masters.
Alpha Gypsum supports master models used to make secondary tooling.
Alpha Gypsum helps maintain stable dimensions during mold replication cycles.

Alpha Gypsum is used in packaging inserts and protective forms in limited, niche applications where rigidity is needed.
Alpha Gypsum supports custom-shaped protective supports for fragile items.
Alpha Gypsum helps maintain shape and resist compression in handled items.

Alpha Gypsum is used in quality control environments to create gauge blocks and reference forms for inspection training.
Alpha Gypsum supports repeatable casting for dimensional comparison exercises.
Alpha Gypsum helps demonstrate shrinkage control and dimensional stability.

Alpha Gypsum is used in art restoration to fill gaps and rebuild missing sections in plaster works.
Alpha Gypsum supports strong, carvable fills that can be shaped after set.
Alpha Gypsum helps achieve smooth transitions for painting and finishing.

Alpha Gypsum is used in specialty cementitious blends to adjust set behavior in some hybrid systems.
Alpha Gypsum supports controlled setting and early strength development in niche formulations.
Alpha Gypsum helps tune workability and finishing time in specialized products.

Alpha Gypsum is used in manufacturing of gypsum-based adhesives for tiles and panels in certain systems.
Alpha Gypsum supports good initial grab and fast set characteristics.
Alpha Gypsum helps improve bond strength and early handling ability.

Alpha Gypsum is used in industrial casting where low expansion and high strength are required for precision.
Alpha Gypsum supports tight-tolerance parts in casting and modeling.
Alpha Gypsum helps maintain accuracy during hydration set and drying.

Alpha Gypsum is used in production of statue bases and display pedestals requiring hard plaster.
Alpha Gypsum supports chip-resistant edges and stable surfaces.
Alpha Gypsum helps provide durable bases for art and merchandise display.

Alpha Gypsum is used in manufacturing of model railway scenery and diorama components for hobbyists.
Alpha Gypsum supports detailed casting of terrain textures and building parts.
Alpha Gypsum helps produce stronger hobby castings that resist breakage.

Alpha Gypsum is used in high-strength gypsum putties for crack filling and surface leveling.
Alpha Gypsum supports smooth application and fast sanding after set.
Alpha Gypsum helps improve hardness and reduce shrinkage in repair work.

Alpha Gypsum is used in industrial supply chains where consistent plaster performance is required across batches.
Alpha Gypsum supports predictable water demand and set time for manufacturing.
Alpha Gypsum helps improve process control in gypsum product production.

Alpha Gypsum is used in performance testing to measure compressive strength and setting time of gypsum formulations.
Alpha Gypsum supports standardized lab testing of gypsum-based products.
Alpha Gypsum helps benchmark new gypsum additives and blends.

DESCRIPTION

Alpha Gypsum is the alpha-form of calcium sulfate hemihydrate produced under pressure in controlled conditions.
Alpha Gypsum is typically denser and stronger than beta gypsum due to crystal morphology differences.
Alpha Gypsum is commonly supplied as a white powder used for high-strength plaster applications.

Alpha Gypsum requires less water to reach workable consistency compared with beta gypsum.
Alpha Gypsum therefore produces hardened casts with lower porosity and higher compressive strength.
Alpha Gypsum sets by hydration to calcium sulfate dihydrate, forming an interlocking crystal network.

Alpha Gypsum crystal shape is more regular and compact, which improves packing and strength.
Alpha Gypsum provides excellent detail reproduction because of controlled particle size and low expansion.
Alpha Gypsum dimensional stability is valued in dental, ceramic, and precision casting applications.

Alpha Gypsum setting time can be adjusted using accelerators and retarders depending on the application.
Alpha Gypsum heat of hydration and set behavior depend on purity, particle size, and additives.
Alpha Gypsum can generate significant heat during set in large castings, so thickness control can matter.

Alpha Gypsum must be kept dry because moisture uptake can cause caking and reduced performance.
Alpha Gypsum should be stored in sealed packaging away from humidity and water sources.
Alpha Gypsum dust can be irritating, so dust control and proper handling practices are recommended.

Alpha Gypsum hardened products can be sanded, carved, and painted after full drying.
Alpha Gypsum water resistance is limited unless protected or modified, since gypsum is water-sensitive.
Alpha Gypsum is valued for high strength, low expansion, and precise casting performance.

Alpha Gypsum is a high-strength gypsum hemihydrate produced by calcining gypsum under pressure or in concentrated solutions to form dense alpha crystals.
Alpha Gypsum sets by hydration to calcium sulfate dihydrate, and this crystallization process creates interlocking needle-like crystals that build mechanical strength.
Alpha Gypsum typically requires less mixing water than beta hemihydrate, so Alpha Gypsum can achieve higher final density and improved compressive strength.

Alpha Gypsum setting time and strength development depend on particle size distribution, purity, water ratio, temperature, and the use of accelerators or retarders.
Alpha Gypsum can be formulated for different working times, from fast-setting systems to longer open-time systems for precision casting.
Alpha Gypsum performance benefits from controlled mixing and proper curing, because premature drying or improper water ratio can reduce strength and increase porosity.

Alpha Gypsum should be stored dry and protected from humidity because moisture uptake can cause prehydration, caking, and loss of performance.
Alpha Gypsum dust can irritate eyes and respiratory tract, so dust control and appropriate PPE are recommended during handling.
Alpha Gypsum should be used with good housekeeping practices because spilled powder can create slip hazards when wet.

PROPERTIES

Chemical Formula: CaSO4·0.5H2O
Molecular Weight: 145.15 g/mol
Common Name: Alpha Gypsum
Chemical Type: Calcium sulfate hemihydrate (alpha form)
Appearance: White to off-white powder
Odor: Odorless
Solubility: Slightly soluble in water (very low); insoluble in most organic solvents
Setting Mechanism: Hydrates to calcium sulfate dihydrate with crystal growth and hardening
Water Demand: Lower than beta hemihydrate, enabling higher density casts (grade dependent)
Strength: High compressive strength after set and dry (grade dependent)
Dimensional Stability: Good detail reproduction and low deformation when properly formulated
Bulk Density: Higher than beta hemihydrate powders (grade dependent)
pH (slurry): Typically near neutral to slightly alkaline (grade dependent)
Thermal Behavior: Non-combustible mineral; stable under typical storage and use conditions
Storage Temperature: 5–30°C, dry, protected from humidity
Shelf Life: Typically 6–12 months in original sealed packaging (supplier dependent)

FIRST AID

Inhalation:
Move to fresh air if dust is inhaled.
Seek medical attention if respiratory irritation persists.
Avoid breathing dust during handling and powder transfer.

Skin Contact:
Wash with soap and water after contact.
Remove contaminated clothing and wash before reuse.
Seek medical advice if irritation persists or if skin becomes dry or cracked.

Eye Contact:
Rinse cautiously with water for several minutes.
Remove contact lenses if present and easy to do, then continue rinsing.
Seek medical attention if irritation persists.

Ingestion:
Rinse mouth with water.
Seek medical attention if discomfort occurs or if a large amount is swallowed.
Never give anything by mouth to an unconscious person.

Note to Physicians:
Treat symptomatically.
No specific antidote is required.
Provide supportive care based on exposure route and symptoms.

HANDLING AND STORAGE

Handling:
Use appropriate PPE including gloves and safety glasses, and use dust protection as needed.
Avoid generating dust and avoid inhalation of fine powder.
Wash hands after handling and before eating, drinking, or smoking.

Ventilation:
Use local exhaust or general ventilation where dust may be generated.
Maintain good airflow during weighing, charging, and mixing operations.
Minimize airborne particulate accumulation in enclosed areas.

Storage:
Store in tightly closed containers in a cool, dry place away from moisture.
Protect from humidity to prevent caking and premature hydration.
Keep containers properly labeled and sealed when not in use.

Spill and Leak Procedures:
Avoid dust generation and sweep or vacuum using equipment designed for fine powders.
Place collected material into suitable containers for disposal according to local regulations.
Clean residues promptly, and avoid washing large amounts into drains where settling may occur.

Handling Precautions:
Control water ratio and mixing procedure to achieve consistent setting time and strength for Alpha Gypsum systems.
Avoid contact with strong acids that may react with mineral materials and affect performance.
Rotate stock using FIFO practices to maintain consistent quality and predictable setting behavior.