Liquid Tooling Materials Selection Guide

(Part 2 of 2: Choosing a Liquid Tooling Material)

After you choose which method is best, you need to decide which material(s) to use. Choosing your material largely depends on your answers to the following questions:

How will this pattern, part, tool or mold be used?
How important is dimensional accuracy?
Is this a prototype or a production part/tool?
How many times will this part be used?
Will it be exposed to heat?
Will it need to be abrasion resistant, impact-resistant, etc?
Are there any special conditions this tool needs to meet?

Please keep in mind that the information below should be considered as guidelines and not rules. The best material for your application will vary depending on the unique characteristics of your project. This is why Freeman offers free technical support to all of our customers.

Flexible Mold Making Materials

Ideal for negative molds (mass casting), flexible parts and gaskets, plaster casting, and prototypes.

Silicone Rubber

Self-releasing, therefore it reproduces high detail
High temperature resistance
Excellent tear strength and elongation properties
Much more user-friendly than latex rubbers
Higher cost than urethane rubber

...see Bluestar Silicone Rubber

Urethane Rubber

Preferred material for concrete and architectural castings due to its abrasion-resistance
Available in a brushable formulation for glove molds/skin molds
Lower cost than silicone rubber
Requires release agents

...see Flexible Urethanes

Filled Mass Casting Materials

These urethane or epoxy materials are filled with glass, aluminum, iron, or other materials, which give them unique properties and in many cases, lower the cost over unfilled materials.

Repro (Fast-Cast Urethane)

Low cost
Fast demold times
Easy to use

Generates less heat than epoxy (ideal for thicker pours)

...see Freeman Repro Fast-Cast Urethanes


Epoxy Casting Resins

Slower, variable gel times  
Higher durability
Wider range of applications
Higher heat resistances available
Higher cost than Repro

...see Epoxy Casting Resins

Unfilled Mass Casting Materials

These urethanes are available in a wide variety of durometers, from very flexible to very rigid. Although higher in cost than most filled urethanes, these materials are more versatile and more durable in thinner sections.

Semi-Rigid Urethane Elastomer

Highest impact resistance
Highest abrasion resistance
Ideal for surface casting and foundry applications

...see Semi-Rigid Urethanes


Rigid Urethane Elastomers

Variable gel times
Can simulate a wide variety of production plastics, thus creating accurate and usable models, prototypes, and parts without expensive tooling
Clear, tinted, and opaque formulations available

...see Rigid Urethanes
...see also Ren Rapid-Prototyping Polyurethanes (for very fast curing)
...see also RenCast Fast Polyurethanes (for medium speed curing)


Laminating Materials

Used primarily in larger tooling applications where weight and overall material requirements becomes an issue, these materials offer a variety of alternatives for creating inexpensive parts and tooling.


Repro Laminating Materials

System includes Repro Surface Coat, Repro Laminating Resin, & fiberglass strand
Low cost
Easy 1:1 mix ratio
Fast 'tack-free' for quick tool construction
3-4 hour demold
Not as strong as epoxy
Not intended for large vertical surfaces

...see Freeman Repro


Urethane Paste Laminating Materials

Strong and lightweight
No sagging on large vertical surfaces
Ideal backup for many surface coats or brushable rubbers (in glove molds)
Easier to use than epoxy paste laminate material
Lower cost than epoxy paste

...see Paste Laminating Materials


Epoxy Paste Laminating Materials

Strong and lightweight
No sagging on vertical surfaces
Easy to apply as backup for surface coats
Higher cost than urethane paste

...see Paste Laminating Materials

Epoxy Laminating Materials

Variable gel times
Lightest Weight
Low cost
Longest working time
Higher heat resistances available

...see Laminating Materials