Description
This water-clear urethane casting resin is designed for applications requiring clarity.
Crystal Clear™ 204 features low viscosity for easy mixing and pouring, curing at room temperature with negligible shrinkage.
The cured castings are UV-resistant and not brittle, allowing for vibrant colors and effects when pigments are added.
This product is intended for industrial use only and is not suitable for home use.
Features
- UV Resistant
- Not brittle
- Vibrant colors with pigment dispersions
Applications
- Encapsulation
- Making prototype models
- Lenses
- Sculpture reproductions
- Decorative cast pieces
- Jewelry
- Special effects
- Props
Technical Properties
- Mix Ratio By Weight: 100A:90B
- Working time: 2 hours
- Cure Time: 48 hours
- Shore Hardness: 80 D
- Specific Gravity: 1.036 g/cc
- Specific Volume: 0.97 cm³/g
- Color: Clear
- Tensile Strength: 24.1 MPa
- Elongation @ Break: 10%
- Compressive Modulus: 303.4 MPa
- Heat Deflection Temp: 49°C
- Flexural Strength: 37.2 MPa
- Flexural Modulus: 1,263.6 MPa
- Compressive Strength: 29 MPa
- Tensile Modulus: 594.7 MPa
- Shrinkage: 0.002 mm/mm
- Index of Refraction at 20°C: 1.49888
- Index of Refraction at 25°C: 1.49830
- Mixed Viscosity: 600 mPa·s
Instructions
Safety
Store and use at room temperature (23°C). These products have a limited shelf life and should be used as soon as possible.
Environmental humidity should be as low as possible. Good workshop ventilation is essential. Wear safety glasses, long sleeves, and rubber gloves to minimize contamination risk.
Wearing a NIOSH-approved respirator will minimize inhalation of residual fumes.
Use in a low humidity environment (below 50% relative humidity).
Mixing containers should have straight sides and a flat bottom. Mixing sticks should be flat and stiff with defined edges for scraping the sides and bottom of your mixing container.
Mixing and Measuring
Liquid urethanes are moisture sensitive and will absorb atmospheric moisture.
Mixing tools and containers should be clean and made of metal or plastic. Materials should be stored and used in a warm environment (23°C).
Stir or shake Part B thoroughly before dispensing. The proper mixing ratio is 100A:90B by weight.
You must use an accurate digital gram scale to weigh Parts A and B properly.
Do not use an analog scale or attempt to measure components by volume.
Dispense the required amount of Part A into a mixing container. Weigh out the appropriate amount of Part B and combine with Part A. Mix slowly, but thoroughly, for at least 90 seconds making sure that you scrape the sides and bottom of your container several times.
If coloring or filling the product, add filler or pigment dispersion to Part B and mix thoroughly before adding Part A.
Pouring, Curing & Performance
If casting into a rubber mold, pour mixture in a single spot at the lowest point of the mold. If encapsulating an object, do not pour the mixture directly over the object. Let the mixture seek its level. A uniform flow will help minimize entrapped air. Bubble elimination is best achieved by pressure casting. After pouring the mixed compound, the entire casting assembly (mold, dam structure, etc.) is placed in a pressure chamber and subjected to 0.42 MPa (60 PSI) air pressure for full cure time prior to heat curing. Castings will reach ultimate physical properties at room temperature in 7 days. Castings removed from mold before recommended cure may exhibit a tacky surface that can be eliminated by exposing casting to 65°C for 6 hours. Pot life and cure time depend on mass concentration and mold configuration.
Post Curing
Castings will achieve maximum physical properties, better heat and UV resistance if post cured. Post curing is recommended if castings are thin or of low mass concentration. Castings should be post cured in a mold or support structure.
Post Cure Schedule: Allow the material to cure fully at room temperature followed by 6 hours at 65°C–72°C. Allow casting or part to cool to room temperature before demolding.
Storage
IMPORTANT: Shelf life of product is reduced after opening. Remaining product should be used as soon as possible. Immediately replacing the lids on both containers after dispensing product will help prolong the shelf life of the unused product.
XTEND-IT™ Dry Gas Blanket (available from Smooth-On) will significantly prolong the shelf life of unused liquid urethane products.
Warnings
CAUTION: NOT FOR HOME USE. THIS PRODUCT IS FOR INDUSTRIAL USE ONLY.
With adequate local exhaust ventilation, respiratory protection is not normally required when using this product. Where risk assessment shows air-purifying respirators are appropriate, follow OSHA respirator regulations and European Standards EN 141, 143 and 371.
Protective clothing (gloves and long sleeves) is required to minimize the risk of dermal sensitization. If breathing is affected or a dermal rash develops, immediately cease using this product and seek medical attention.
Read SDS before using.
