Does Styrofoam Dull Knives?

By Ryan Leavitt •  Updated: 04/28/21 •  5 min read

If you want to take care of your knives properly, you should make sure to avoid cutting and slicing things that can dull your blade.

There are a lot of materials that can dull the edge out of your knife, so you really have to be careful with what materials you cut.

But figuring out which materials are bad for your blade can be tough, and one question that is asked by a lot of knife owners is, “does styrofoam dull knives?”.

The answer is yes, styrofoam can dull your knife, but not significantly. Just about any material that you cut will dull a knife to some extent, which is why you will need to sharpen your knives from time to time.

If you’re only cutting a bit of styrofoam, feel free to use any of your knives, since they can always be honed back into shape easily.

But if you plan on cutting and carving big chunks, you may want to use an X-acto knife, as they are very sharp, easy to control, and don’t cost too much money.

If you’ve been wondering how to properly carve styrofoam, you’ve come to the right place as we’ve made a step-by-step guide to make the process much easier for you!

Read on to learn more.

How Should I Cut Styrofoam?

Score It First!

First things first, scoring the styrofoam will make it much easier to cut through and break, regardless of the tools you’re using.

Ideally, you would want to do this with a small, sharp, and thin object to create a cutting line where you need to cut the styrofoam.

Do this carefully, and try to keep the score as straight as possible.

You can use a butter knife, credit card, or even a craft knife.

Once it has been scored, simply break it off along the scoreline to create a clean break on the styrofoam.

This is great if all you’re looking to do is create big chunks of foam, but if you need to do more exact and intricate cuts, you’ll have to choose the right tools.

Choose The Right Tools

In this section, we’ll take a look at the different tools that you can use to carve styrofoam, whether if it’s for an intricate cosplay costume, simple decorations, or props for a theater production.

Craft Knives

This is a great tool for making precise cuts on styrofoam.

They are very sharp and relatively inexpensive, so you won’t have to worry about dulling out expensive blades.

On top of that, since they are so easy to control, intricate carving patterns and techniques are much easier to execute.

This is ideal for cutting thin pieces of styrofoam, but if you’re carving chunks thicker than 1”, the blade might end up flattening or compressing the foam, which results in malformed pieces.

Waxed Serrated Knives

This is another great way to get clean cuts on your styrofoam.

To wax your knife, run it several times over a white candle.

The serrated blades will cleanly tear through the foam, while the wax will make it much easier to cut through.

Make sure to use long sawing motions and even pressure with this technique to keep your slices as neat and even as possible.

Electric Knives

If you aren’t that good at freehand carving, using an electric knife is another great choice.

You can use just about any electric knife for this task, and it will result in very clean and even cuts.

Make sure to make an outline of where you want to cut beforehand, then all you have to do is turn the knife on and cut along the line.

It’s important that you don’t exert pressure and instead let the electric knife do the work for you.

Use A Hot Wire Cutter

This is one of the best ways to get a clean cut on your styrofoam without risking dulling out your blades.

You can buy hot wire cutters at a lot of craft and home improvement stores, so they aren’t too hard to find.

They work by melting the foam with a heated wire, which creates a much smoother edge as compared to when being cut by a knife.

This is a great way to get unique shapes when cutting through the foam.

Be careful when using these tools, as the wire can get very hot, and also make sure to apply a consistent and even pressure along the cutting line to make sure you get the results you’re aiming for.

Scoring the styrofoam beforehand might also help out a lot with this method.


Styrofoam is a tough material to cut because of the way it breaks apart.

But it is also a very useful material for decorations, props, and even as components for an intricate costume!

And as long as you follow our tips for cutting styrofoam and make sure not to use your expensive carving knives on the material, then you can easily get clean and unique cuts without dulling out your blades!

Ryan Leavitt

Hi my name is Ryan Leavitt a Marine Corps Veteran and currently an over the road trucker (Long Haul). I am no expert chef but am enjoying preparing my own meals on the road and testing all the different knives.