Molding Rubber Archives

Why isn’t my urethane rubber mold curing?

There are a few reasons urethane rubber might not cure. If you’re seeing spots or streaks of uncured material, it’s likely that the material wasn’t…

How can I minimize air bubbles in my mold?

To combat trapped air, you’ll want to work in a temperature-controlled environment. Also, mix the material slowly and pour it into the lowest part of…

Why am I seeing bubbles and pinholes on my urethane mold?

Bubbles usually indicate that there is trapped air in the mix. One reason bubbles form on the rubber’s surface is due to moisture. Urethane is…

What is your price?

VFI strives to offer competitive prices for our molding rubbers, but it will ultimately depend on a handful of factors, including the availability of raw…

Do you sell to other concrete companies?

We have a vast customer base in the concrete industry of manufacturers who use our urethane rubber for precast panels, manufactured stone, cast stone, architectural…

How long have you been in business?

VFI has been manufacturing high performance thermoset polymers for almost 30 years. While our origins were a little different to what we currently do, we…

Does your product work?

VFI prides itself on only offering materials that have been thoroughly tested using standard ASTM methods. We have determined through feedback from our customers that…

Can you make your urethane in any other colors?

VFI’s TDI-based urethane rubbers come in two distinct colors: blue and neutral. If you want to add color to the neutral version, urethane pigments can…

How should I store my urethane rubber mold?

Clean the mold before you plan to store it. We recommend storing them indoors where there is no chance of UV exposure. The environment should…

Can I store my molds outside? In sunlight?

Do not store your molds outdoors or in direct sunlight. Outdoor conditions can cause the mold to deteriorate before its typical lifespan. UV rays will…

How should I clean my urethane rubber molds?

Urethane molds can be wiped down with soap and water before they are used again or stored for future use.

How often should I use mold release during the casting process?

Because urethane will adhere to anything, apply release after each casting. The release will have worn away during the demolding process, so it’s important to…

How many pulls can I get out of a urethane rubber mold?

The amount of pulls you can get from VFI urethane rubber depends on the properties, what you’re using it for, and how you take care…

How soon can I use the mold after demolding it? (How long does it need to cure?)

Most VFI molding rubbers must sit for a minimum of 16 hours at room temperature (77°F) before they can be demolded. After demolding, they must…

How long until I can no longer repour the material?

Customers who pour large molds will need to pour several batches of rubber to create the thickness needed for a strong mold. As a standard…

What temperature should I pour the rubber at?

VFI always recommends pouring in the same conditions you will be using the cured product. If you expect to work in warm conditions, pour the…

Why is my urethane rubber mold expanding?

If you cast in a really cold environment and then use the mold in a very warm environment, you might notice your mold temporarily expand….

Why is my urethane rubber mold shrinking?

If you cast in a really warm environment and then use the mold in a very cold environment, you might notice your mold temporarily shrink….

Does temperature affect the mold making process?

Yes, the temperature of the environment, material, and models affects liquid urethane when making molds. If the temperature is too cold, it can slow down…

How do you mix the molding rubber?

VFI recommends a specific double-mix method for mixing our urethane molding rubber. First, you will determine how much material you need and measure that out…

Should I measure by weight or volume?

Whether you should pour by weight or volume depends on your unique molding process. If you pour rubber in smaller quantities, either method works. To…

Should I use silicone or acrylic caulk to seal my mold box?

When sealing your mold box, you should use acrylic caulk because silicone can inhibit the cure of urethane.

How do I prepare the mold box and model before pouring urethane rubber?

All edges of the mold box must be sealed as well as the edges of your models, so the molding rubber is not able to…

What happens if I use too much release?

Using too much release may affect the surface of your castings. The surface may have a shiny or gloss-like appearance, which may not be desirable…

Can I use an oil-based release with urethane rubber?

Do not use an oil-based or biodegradable concrete release like soy bean form oil when molding with urethane. These materials can cause your mold to…

Do I need a release agent? What kind?

Non-porous surface to urethane: When working with urethane rubber, you must use a release agent to prevent the material from bonding with the casting surface….

What kind of clay works best with urethane rubber?

When making a mold, use clay to seal the mold box walls and models so the liquid material cannot slip through or underneath. When using…

How thick should my mold walls be?

Pour thickness will depend on the hardness of the rubber chosen. Because softer rubbers are more flexible, they’re more prone to tearing. Generally, the softer…

How much urethane rubber do I need to make a mold?

To determine how much mold rubber you need, you’ll first need to calculate the cubic volume (formula: length x width x height) of your mold…

What durometer of rubber do you think I need?

The best durometer for your project will depend on your unique project requirements. For cast stone applications, we recommend using one of our 25-40 A…

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Why isn’t my urethane rubber mold curing?

How can I minimize air bubbles in my mold?

Why am I seeing bubbles and pinholes on my urethane mold?

What is your price?

Do you sell to other concrete companies?

How long have you been in business?

Does your product work?

Can you make your urethane in any other colors?

How should I store my urethane rubber mold?

Can I store my molds outside? In sunlight?

How should I clean my urethane rubber molds?

How often should I use mold release during the casting process?

How many pulls can I get out of a urethane rubber mold?

How soon can I use the mold after demolding it? (How long does it need to cure?)

How long until I can no longer repour the material?

What temperature should I pour the rubber at?

Why is my urethane rubber mold expanding?

Why is my urethane rubber mold shrinking?

Does temperature affect the mold making process?

How do you mix the molding rubber?

Should I measure by weight or volume?

Should I use silicone or acrylic caulk to seal my mold box?

How do I prepare the mold box and model before pouring urethane rubber?

What happens if I use too much release?

Can I use an oil-based release with urethane rubber?

Do I need a release agent? What kind?

What kind of clay works best with urethane rubber?

How thick should my mold walls be?

How much urethane rubber do I need to make a mold?

What durometer of rubber do you think I need?

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