It depends on the density or the foam but in some cases cutting it with a hot knife leaves it quite smooth.

How to cut foam board smoothly. The board should snap on the line. Follow these steps to make straight cuts in thin foam board: To begin, measure the board and mark where the start and end points are for your intended cut line.

Measure and mark where you’d like to cut. To protect the work surface, use a cutting board or cutting mat when cutting styrofoam. If the board is too thick to snap.

If it’s very dense use fine abrasive paper. Because the density and size of foam materials vary greatly, it is very important to know which foam material is suitable. This is the best way to cut foam board insulation with a utility knife.

Buy a versatile cutter invest in a cutter that cuts various materials and can cut foam board up to a thickness of 13mm. Measure and mark where you’d like to cut. 2 the 5 best tools for cutting foam board.

Or you may be able to. These ridges may assist you in manually measuring while. How to cut foam perfectly 1.choose the right cutting head:

7 essential points to successful foam board cutting 1. The bottom of segmented knives has ridges. Remove the straightedge and clamps, hold the board upright, then apply pressure along the back side, behind the cut line.