DIY Polyurethane Foam Liquid Formula

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Things You'll Need

  • Mold

  • Mold-release spray

  • Large, disposable container

  • Stirring stick

  • Two-part urethane liquids

Baby car seats often use urethane foam as padding.

Polyurethane foam comes in solid and springy formulas. Solid foam has many uses such as for temporary stages and flooring, wall insulation, theater props, coolers and boats and airplanes. The soft foam is used for packaging, padding, seat cushions and bedding. You can make either kind of foam using two-part foam mixtures. When working with the mixtures, make sure to wear eye protection and a respirator mask to protect your eyes and lungs when working with the semi-toxic materials.

Solid Foam

Step 1

Choose a mold for the foam that you want to make. Solid foams are typically used for things such as wall insulation, theater props and siding for boats. Use a mold for whatever object you want to create with the foam.

Step 2

Spray the mold with a mold-release spray. Allow the spray to dry for 24 hours before adding the foam liquid.

Step 3

Mix the two parts of the foam with an even 50-50 split between the two mixtures in a large, disposable container. Stir the two mixtures together with a stirring stick.

Step 4

Pour the liquid into the mold within 15 minutes of mixing the liquid. The foam starts to set within 15 minutes.

Step 5

Wait for the foam to cure overnight. Keep the mold in a room that is around 70 degrees Fahrenheit so that the foam can cure. Colder temperatures will prevent proper curing. Pop the foam out of the mold after 24 hours.

Flexible Foam

Step 1

Follow steps one and two as outlined above for preparing the mold for the foam.

Step 2

Mix the two parts of the urethane foam mixture together with a ratio of 28 parts of hardener and 72 parts of urethane foam liquid. Mix the two parts together until they start to expand.

Step 3

Pour the foam into the mold. Leave a small amount of room for expansion. The foam should be fully expanded within 15 minutes.

Step 4

Allow the foam to cure for 24 hours in at least 70 degrees Fahrenheit.