How to Cut Foam Pad
Step 1
1
Use a long serrated knife to easily cut thick foam. Small air holes form inside the foam when it’s heated, similar to the air pockets that are created inside bread when it’s baked. That’s what gives foam its light, airy consistency — and it’s also why it can be hard to cut. If you use a serrated knife like the kind used for cutting bread, it will make the job much easier.
This works best for foam that’s at least 2 in (5.1 cm) thick. Ideally, the blade of the knife should be longer than the thickness of the foam. That will make it much easier to slice all the way through.
You may have better control over a long knife than some of the other options, so this might be a good choice if you need to make detailed cuts.
Step 2
2
Get speedy cuts in thick foam by using an electric kitchen knife. If you happen to have an electric knife (like the kind used for carving turkey), you can use that to quickly and easily trim your foam to size. These are especially handy if you’ll be working on a large project or if you need to cut the foam at an angle.
When you’re using an electric knife, it’s a good idea to line up the foam so the line you’re cutting is hanging off of your work table. That way, the edge of the knife won’t make contact with the surface while you’re cutting.
If your foam is less than about 2 in (5.1 cm), it’s probably easier to use a rotary cutter or craft knife.
You can purchase electric kitchen knives at most department stores. They’re usually pretty inexpensive, so it might be worth picking one up if you have a big project to work on.
Step 3
3
Opt for a rotary cutter to cut thin foam pieces. If your foam pad is 1⁄2 in (1.3 cm) or less, a large (60mm) rotary cutter can make short work of the job. Simply mark where you want to cut the foam, then roll the blade over the line you made.
Rotary cutters can be useful for cutting curved lines, but they might not be ideal for intricate work.
You could also use a box cutter for thinner foam, as long as the blade is about the width of the pad. Sharp scissors may work for this, as well. However, these aren’t ideal for cutting thicker pads.
Step 4
4
Try a hot wire cutter for horizontal cuts, but use caution. Hot wire can easily slice through foam, and many people prefer them if you need to cut large foam pads into horizontal slices. Hot wire cutters run an electrical current through a wire that’s held taut by a frame, and you just have to push the wire through the foam. However, there’s some concern that this technique might produce toxic fumes from heating up the foam, so be sure to work in a well-ventilated area if you choose this technique.
In addition, if you move too slowly or you pause while you’re cutting, you might melt the foam, causing it to harden and possibly become misshapen.
Hot wire cutters are only safe to use on foam made of polystyrene and polyethylene. Do not use them to cut foam made of polyurethane — the fumes produced would be very toxic.
Be very careful not to touch the wire — it will burn you.
