How to you cut out excess expanding foam?

Question

I used polyurethane expanding foam to block the space between the wall and the pipes under my kitchen sink (I have a mice problem).

Now there's a big mass of foam around my pipes and I understand I have to remove it mechanically.

What is the best way to remove the excess foam without pulling out the whole piece of foam (and having to do it all over again).

What tool would you use for that?

Knife? (what kind)
Exacto?
Saw?

Answer 1

depending on the space you have to work in I use a small hack saw or small saw, then finish off with a bit of sand paper if you are so inclined

A knife or exacto will make you bleed :-)

Good Luck

Answer 2

Great stuff cures rigid, and can be easily carved, shaped and sanded. Actually, a cheap steak knife - the kind with a somewhat flexible blade - is one of the best foam carving tools there is, because the blade can be shaped a little, which makes it easier to get at the areas that need carving. Rasps, rifflers, Surform tools, and sandpaper also work well. Great Stuff is a closed cell urethane foam, meaning that most of the bubbles that make up the foam remain closed - as opposed to furniture cushions, for example, which are made of open cell foam. Because of that, it has good water resistance and won't soak up water like a sponge. It's also paintable, which will help seal it. It does seem to become brittle over time if left exposed to the elements, and develops a "crumbly" surface, so painting or sealing is probably a good idea. A couple of important things to note: The expansion of the foam can generate significant force, so you need to be careful not to "trap" it in an enclosed space where the expansion pressure can cause distortion in the surrounding materials. Also, take the protective clothing precaution you'll find on the can to heart. The foam is very sticky and hard to get off of anything it contacts, including skin. Whatever you do, don't get it in your eyes!

Answer 3

Removing Expanding Foam

Answer 4

If you have one, try an electric knife, i have found they are perfect for cutting foam rubber, not quite as good for stiff foams.

If you don't have an electric knife, a serrated knife or hacksaw blade would work, but not make such a clean cut.

Wear breathing protection when cutting.

If you end up re-foaming, make a barrier out of plastic or cardboard to prevent the foam from expanding into areas where you don't want it..

Answer 5

Ive found that a simple hacksaw blade, just by itself works well, but in very tight fitting spots.... Fishing Line!... you can cut the foam with a length of fishing line pretty easy, and its handy to wrap around the pipes, to cut with, if you have no room for the hacksaw blade.

Have Fun!

Answer 6

I've always used a razor blade or utility knife. The foam is fairly easy to cut whatever you use.

Answer 7

Good gravy man, it's just foam. Grab the knife and hack off the excess.

Answer 8

Some kind of serrated knife is the best. I used a bread knife when I did a similar job in my bathroom. Wetting the blade helps.

Answer 9

Heat up a putty knife and the knife will slide right into the foam

Answer 10

use a hack saw blade without the saw. cuts easy watch out for pipes