2 Part Foam for Seat Fitting, 2 Quart Kit


2 Part Foam for Seat Fitting, 2 Quart Kit


This polyurethane foam kit produces a rigid foam with a density of about two pounds per cubic foot. It is ideal for making custom fitted seats or for strengthening composite bodywork parts.

When the two parts are mixed, they begin to react within about one minute. Most of the foaming occurs within the next several minutes. About 15 minutes is required for the foam to set. Allow several hours before any secondary operations are attempted such as sanding or carving (if required). The resulting foam will not absorb water and is not affected by polyester resin, epoxy resin, gasoline or oil. The compressive strength of the foam is 36 psi. It can withstand operating temperatures of up to 200°F. One kit is enough for about 3 typical formula car seat inserts.

Full instructions for this kit are below.


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To pour a two-part foam seat insert, you will need:

  • 1 five-gallon bucket (clean and dry inside)*
  • 2 measuring cups (paper cups, or plastic half-liter bottles with the tops cut off)*
  • Wire coat hanger*
  • Many plastic garbage bags*
  • Newspaper*
  • Tape (masking or cheap electrical tape preferred)*
  • Driver
  • Two or more helpers

* Everything must be disposable except the driver, car, and helpers.

The helpers should wear old clothes they do not plan to wear again. The driver can either wear old clothes, or he can wear his driver's suit if it is securely and completely covered with garbage bags. The driver should also consider wearing an old hat. All long hair should be tied up or tucked out of harm's way. The foam will not come out of fabric or hair, and it stays on your skin for several days.

Begin by lining the inside of the car with plastic garbage bags. The object is to prevent any spilled foam (and it will spill) from getting on any surface of the car (it will not come off easily). Tape the garbage bags in place, but leave a little slack so they do not tear when the driver climbs in. Spread newspaper on the floor around the car and under your mixing area. If the driver is wearing his driver's suit, cover the suit as completely as possible with a layer of garbage bags.

Determine where the driver needs the most support: behind the back, around the ribcage, or under the seat. Loosely tape one garbage bag in the area where support is needed. Tape it with plenty of slack, because the foam will pull the bag as it expands. Do not tape it too securely, because you want the tape to let go before the bag does. Have the driver get in the car.

Now pour some of Part A into one measuring cup and an equal amount of Part B into the other cup. Remember that the foam will expand a lot; do not try to fill the bag with liquid! A second pour can be added later to build up the seat if it is not large enough. This is much easier than trying to clean up several cubic feet of extra foam.

Keep in mind that the closer the mixture is to 1:1 A:B, the stronger the seat will be. Pour the two parts into the bucket and mix with the wire hanger bent into an appropriate shape. The two parts will begin life looking like maple syrup and maple syrup "lite," but the mixture will resemble pancake batter in about one minute. When it does, it is starting to foam and is ready to pour. Do not delay the pour for too long; the mixture pours less well the more it foams.

Now have one or two helpers hold the bag open while another helper pours the mixture, hopefully into the bag and not on the other helpers. The driver can assist by keeping his weight off of the bag and squishing the foam into place where he needs it. Once the foam is in the bag, the driver can begin to settle back into the seat, gradually resting his weight on the foam as it sets up and expands around him. The foam gives off a little heat as it sets up, so sit back and enjoy the feeling!

The foam will be done expanding about five minutes after it starts. About fifteen minutes later, the foam will be hard enough that the driver can get out (avoid stepping on the insert) and the foam will hold its shape. Allow a few more hours before removing the insert from the car, peeling the bag off, and trimming as needed.