How to Cut Closed-Cell Foam

Closed-cell foam is a top-rated product, and it's easy to see why. It's durable and protective, and comes in a range of shapes, colours, sizes and thicknesses, which has pushed it to the top of the charts for many uses. Fortunately, it's straightforward to work with – whether you're making weather stripping or packaging, it's likely perfect for your needs.

What to cut closed-cell foam with

Open-cell foam is typically cut with scissors or a hot wire. Closed-cell foam is easily cut with a non-serrated blade such as a utility or craft knife. Scissors may also work, depending on how thick the foam is and whether you find them easier than a craft knife for getting the right shape.

Cutting thin foam

If your polyethylene roll is less than 5mm thick, sharp scissors should do the job. Note that they can leave jagged edges, so for a home or recreational project that probably won't matter, but for something professional or for card making, a utility or craft knife is the better choice. Anchor the foam to avoid creasing, start cutting from the outside edge and keep going until you've cut all the way across – don't stop once you've started – and always cut on a flat surface.

Cutting thick foam: the multiple-pass method

If you need to cut closed-cell foam thicker than half an inch, it's likely too thick to pass the blade through in one go, so use a multiple-pass approach. Once you've established your cut line, begin and keep the blade moving without stopping, making each pass as deep as you can until you're through.

Expect some uneven edges

Because polyethylene is a bubbly material thanks to its closed-cell structure, the cut may not be perfectly clean and can leave a slightly uneven edge. For related projects, see our guides to painting foam and making a template for foam.

To get your supply of closed-cell foam, visit eFoam. Whether you need cross-linked polyethylene or non-cross-linked polyethylene foam, contact our team today to discuss.

Frequently asked questions

What is the best tool to cut closed-cell foam?

A non-serrated blade such as a utility or craft knife. Open-cell foam is usually cut with scissors or a hot wire, but for closed-cell foam a craft knife gives the most control. Sharp scissors can handle rolls under 5mm, though they may leave jagged edges.

How do you cut thick closed-cell foam?

Use a multiple-pass method. Once you've marked your line, keep the blade moving without stopping and make each pass deeper until you're all the way through.

Does closed-cell foam cut cleanly?

Not always. Because polyethylene has a bubbly closed-cell structure, the cut may not be perfectly clean and can leave a slightly uneven edge.