Closed cell foam is a unique material that, in its various formulations, is durable, resilient, and can be found in blocks and sheets, or in thicknesses thin enough to behave like cloth. Due to this versatility, people often find uses for it in their daily lives. However, having foam cut to size every time you need it is unrealistic. Fortunately, closed cell foam is an incredibly easy material to work with. Whether you’re making pipe wraps, gaskets, weatherstripping, or anything else, you’ll need to know how to cut closed-cell foam with precision. By taking the following steps into account, you should be able to easily cut through multiple closed cell foam materials.
NOTE: These instructions exclude expanded polystyrene (EPS), which is best cut with a hot wire.
Starting
Before we address the different methods of cutting foam, it’s important to address the materials you’ll need. Unlike open cell foam, closed cell materials should be cut with a straight, non-serrated blade such as a razor or craft knife. These knives work well because their blades are disposable and easy to replace as they become dull. Scissors can also be used for smaller informal projects, though they are only effective on particular types and thicknesses of foam. It’s also smart to have a ruler for cutting. Finally, always cut the foam on a stable surface that will not get damaged.
Upper: Neoprene, Cross-linked Polyethylene, Gym Rubber and Roll Polyethylene
Neoprene is a rubbery material, cross-linked polyethylene (XLPE) is slightly “plastic”, polyethylene roll is a thin, sheet-like material similar to XLPE, and gym rubber is spongy, but can be the softest material or firmer among these four types depending on the formulation. Despite these differences, the physical structures of these materials are similar enough that they can be approached in the same way when cutting.
using scissors
When it comes to neoprene, gym rubber, XLPE or polyethylene rolls, the first thing to consider is the thickness of the material. If you are working with sheets that are 1/8″ thick or less, you have the option of cutting with sharp scissors. Scissors are only recommended for recreational projects because they can leave jagged edges. If you are making shapes for bath toys, or trimming the backing for card making, scissors are fast and effective.Because of its flexibility, PE roll is the easiest of these four materials to cut with scissors.
Single pass cutting method
For precise projects involving materials thicker than 1/8″, you’ll want to cut with a straight blade. Thickness should again be considered, as it will dictate the method you use to cut with the knife.
If you are cutting sheet 1/2″ or less, you should use the single pass method, where you make a single stroke of the blade that cuts through the entire thickness of the material. Simply follow your pattern down the foam until you have the cut you want The single pass method ensures the cleanest edges, although it is not recommended for foam larger than 1/2″ as it becomes difficult to move the blade through the material smoothly. Using the sharpest blade possible is vital to the one-pass method, as dull blades can snag once you get to the heart of the material.
To make your cut, make sure the foam is anchored at the beginning of the cut to prevent the material from crinkling under pressure. Start cutting from an outside edge whenever possible and don’t stop cutting once you’ve started.
Multi-pass cutting method
For closed cell foam thicker than 1/2″ it becomes difficult to cut a blade through the material in a single pass. Attempting to do so can leave snags or sloppy cuts. Fortunately, the multiple pass cutting method will get the answer. job done well on thick sheets of closed cell foam. Using a straight edge that runs the entire length of the cut is the most important aspect of this strategy, as you will need a guide line to follow as you make multiple cuts through the foam.
Once you have established your line of cut and your straight edge is in place, begin cutting exactly as you did in the single pass method. But instead of plunging the blade all the way through the foam, just cut about 1/8″ to 1/4″ of the way; just enough to keep the blade moving without force. It is also very It is important that each shallow cut extends the full length of the foam. Continue to make these long, shallow strokes along your straight edge, cutting deeper with each pass. Do this until you have completely cut through the sheet.
Cut: Polyethylene:
One of the most widely used closed cell foams, polyethylene has a wide range of densities that affect the cell size, firmness, and flexibility of the material. At its lower densities, it has an inconsistent bubbly cell structure, which can affect edge cleanliness. Therefore, we suggest not using scissors when cutting polyethylene. Follow the steps for single pass cutting on sheets greater than 1/2″ thick and for thicker pieces of polyethylene foam, use the multi-cut method.