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Liquid Polyurethane Rubber | High Tear Formula
These polyurethane liquid mold rubbers are soft to mid-range hardness, high-performance, room temperature curing systems. They offer superior flexibility and toughness allowing durable molds to be made from relatively simple to the most highly detailed, undercut and complex models. The Polytek 74-Series liquid mold rubbers are supplied as pourable liquids so poured block and blanket molds can be made with ease; thickening agent can be easily added to make brush-on molds.
Pourable Rubber Curing
Poly 74-45 liquid polyurethane rubber cures to a very tough, high-tear, high-elongation rubber. This product is ideal for high volume concrete and plaster casting and is a very popular option for casting decorative architectural concrete panels and accessories.
Poly 74-45 molds can be poured as supplied or brushed-on by mixing in PolyFiber II thickener or Fumed Silica, also known as pyrogenic silica sand. Poly 74-45 liquid rubber is an excellent multi-purpose, economical mold material that will provide long mold life, durability and consistent performance under repeated casting.
- Shore A20 to A55 hardness liquid mold rubbers.
- High-strength, abrasion-resistant, longest lasting molds.
- Reproduces fine details.
- Pourable or brushable (see “Thickeners” under “Accessories” for brushing).
- Can be accelerated for rapid cure.
- Economical & versatile.
- Ideal for the most demanding mold making applications.
- All rubbers can be demolded after ~16 hours.
Molds made from Poly 74-45 are also used for casting plaster wax (candles & lost wax varieties) and limited resins and foams (with the proper release agent).
- Precast concrete casting
- Architectural GFRC
- plaster casting
- Art foundries
- sculpture and décor reproduction
- Numerous hobby, craft, prop and display mold making and casting projects
- View more applications in the 74-Series product photo gallery.
| Mix Ratio | Shore Hardness | Pour Time | Cured Color |
|---|---|---|---|
| 1A:1B by weight | A45 | 30 min | Yellow |
| Mixed Viscosity | Specific Volume | Demold Time | Shrinkage Upon Cure |
|---|---|---|---|
| 2,000 cP | 27.5 in³/lb | ~16 hr. | Nil |
*Shrinkage is primarily caused by gelling while hot then cooling. Parts that cure with minimal temperature rise exhibit minimal shrinkage.
Product Literature: Technical Bulletin | Safety Data Sheets | Physical Properties Bulletin | Sealer & Release Agent Selection Guide
The color of polyurethane Part Bs may change in color from batch to batch or may darken with age, but product performance is not affected. For additional physical property specifications, refer to the Physical Properties Bulletin.
