Are The Materials Safe To Use?

General Statement – Smooth-On materials should be handled with the same care you use when handling household cleaning products. Common sense should rule the day. For example, you would not want your children to use these materials.

Our liquid rubbers, plastics, foams, release agents, etc. are safe to use if directions are read and followed carefully. Not respecting these chemicals and exercising caution when using them can result in a trip to the hospital (see “sensitization” below).

Do not use these materials in your home. Use them in your garage, dedicated workshop or basement with good ventilation. Keep children and pets away while using these materials.

First, read and understand the technical bulletin and Material Safety Data Sheet for the product you are using. A technical bulletin and MSDS is available for any Smooth-On product at

There are different health risks associated with different materials.

Do not assume that because you are familiar with one material that the same handling procedures apply to a different material.

Protect Yourself – You should wear long sleeve garments and disposable gloves to minimize skin contact. Safety goggles will protect your eyes in the event that inadvertent splashing of a material occurs.

Skin Contact? Lightly wipe affected area immediately with solvent and then wash thoroughly with soap and water.

Eye Contact? If contaminated, flush eyes with water for 15 minutes and seek immediate medical attention.

Ventilation – Avoid breathing in plaster dust, mist from aerosol sprayers or fumes of any kind, etc. When using any material associated with mold making and casting, you must have “room size” ventilation (400 ft2 / 38m2) or greater.

If using these materials on a regular basis, you should install an external ventilation system in your workshop and use all materials in proximity to the working vent. Wearing a NIOSH approved respirator will further minimize risk of inhalation.

Spraying Material – If you are spraying rubber, plastics or foams, try to do your spraying outdoors in an open space. Regardless of spraying outdoors or inside, anyone in the spray area must wear a NIOSH approved respirator and disposable gloves at the very least.

Using Aliphatic Isocyanates – There is a class of polyurethane chemistry known as “aliphatic isocyantes” that require extra handling precautions. These are for “industrial use” only and should not be used by students, hobbyists, etc..

Which Smooth-On Products Are Aliphatic Isocyanates?

· Any “Crystal Clear” liquid plastic product.

· SMASH! Plastic

· Clear Flex 50 & 95 Urethane Rubber

· Task 12 Plastic

If using one of these products, you must wear a NIOSH approved respirator, long sleeve garments and disposable gloves to avoid skin contact.

Sensitization – if you are having an allergic reaction while using polyurethanes, stop using them and seek immediate medical attention.

Symptoms Include; if you are having trouble breathing, experiencing throat discomfort, itching eyes, and/or a skin rash, you may be having a reaction to these materials.

Cease and Desist – Permanently. If you experience these symptoms following any exposure to a urethane product, chances are you have become sensitized and you will experience a reaction every time. At this point, you should avoid using urethanes.

The International Life Cast Museum would like to thank Smooth-On Inc. for allowing us to reprint the above information. Please note that the safety concerns, although referencing material produced by Smooth-On Inc., has some great practical advice on safety for all life casters.

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