Spray Foam Safety and Application

 

Important Safety Issues

  • Spray foam is highly flammable when it's curing (for about an hour). Turn all water heaters, furnaces, etc. down to pilot setting while the foam is curing. Have no ignition sources nearby.
  • Protective Eyewear: Make sure to wear protective eyewear at all times, because if that stuff dripped down and got in your eye, it may cause irreversible damage.
  • Wear Gloves. Long sleeves and a hat are helpful too. If it gets on the skin, it will stay for a minimum of three days and make a big black mark. You can use acetone to get it off if applied immediately, but some are sensitive to this rather toxic solvent.
  • Foam in Clothing or Hair: If it gets on clothing or hair, don’t touch it until it dries, because it just smears everywhere. After it’s dry, you can cut it off easily.
  • Read the instructions and warnings on the can before using (even though some warnings are for liability purposes, it's still good to be aware of them.)
  • Practice on scrap material before spraying your first time.

 

Application

1. Go Light. Only slightly press the trigger, especially as you’re starting. Be aware that regular foam triples in size when it cures and will reach fill size after about an hour. (Minimally-expanding types are available and should always be used around windows and doors or other areas where materials can bend.) Go light on the application, then come back and check it out after at least 20 minutes to see if it's created giant fungus-like bubbles of foam dribbling down your previously clean wall. These can easily be trimmed with a utility knife or a small, fine-toothed saw (such as a hack saw) once they are completely cured.

2. Foam or caulk? Foam should be used only in cracks that are at least 1/4" wide (wide enough for the nozzle to fit into.) On a flat wall, foam will just tumble down and splat on the floor. For cracks narrower than ¼” use caulk.

3. Shake can for at least 60 seconds before using, and often during use. If the foam stops coming out well, shake some more - but look around you first! If there is foam on the end of the nozzle as you shake, it will fly through the air and stick to someone or something. You can either take the nozzle off before shaking, put a latex glove over the end, go outside, or be very, very careful.

4. Spray with the can upside down to help get the last of the foam out—or anytime you are losing propellant. The propellant gases then go to the top and push the foam out. If using a professional nozzle, many will not spray more than a short time if the can is not upside down and if this happens too often, you will lose propellant and not be able to get the foam out.

5. If foam at the end of the straw cures, you can snip off a half inch of the end and continue to use it and/or use a thin metal rod, such as a straightened coat hanger, to clear it.

6. Don’t foam in Minnesota in the winter. The contents should be kept at room temperature prior to use, or at least more than 50 degrees. By the same token, don’t leave it in the car on a hot day. Temperatures over 120 degrees can result in a very sticky back seat, or far worse.