I have been collecting many materials ver the past two years while waiting for our glowforge.
I had dis-assembled shelving in our basement and retained the masonite back panels.
I cut out all of the bad spots and made pieces that would fit in the glowforge. The thickness is 0.122
The boards are over 25 years old and were manufactured by the wet process and the back has the screen impression and is not as hard as the front side. I had no problem cutting and engraving as you can see from the photo. The background is a manila folder so the contrast is not great. I apologize for the poor photography.
It worked nice for the box since the edges are much cleaner than you can get with a good saw and
the kurf seems to be narrow as compared to that with birch plywood. Also with the box the rough backside is not seen.
I have seen many posts on the net were masonite would not cut or would make a lot of dust.
Maybe some kinds have resin added which makes it difficult to cut with the laser.
