Can we cut and engrave sign foam with our glowforge?
Do you mean the HDU (High Density Urethane) boards?
I have not tried this product specifically but something you should know is that urethane products will give off hydrogen cyanide gas when burned/lasered which is pretty nasty stuff.
I HAVE lasered other urethane plastics, like solid cast items I cast from molds. HDU being foam, I’m sure the laser can cut it easily but because it does have a cell structure, it may not produce a desired surface finish like you can get with traditional carving. (It cuts like butter with an X-acto)
I’m going to move this thread to Beyond The Manual before staff gets to it. 
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The expanded pvc ones are dangerous to both you and your machine.
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Yes, HDU. OK… thanks for responding and moving.
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There is a brand name of “Sign Foam” and their product is urethane, which is why I asked specifically about that to clarify that it wasnt something else like Sintra.
You’re welcome. I am sure it will cut and engrave but urethanes do tend to get melty so the quality might be questionable. The HCN gas is more of a concern that you don’t breathe so you want to make sure you dont have any leaks in your ventilation. Being foam, a good portion of it is air which means less volume of bad stuff.
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Is this different from the foam board type stuff you can get at practically any department store (like WalMart) ? I have thought of doing some stacked model cuts from the foam board, but not at the expense of my laser.
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OOOOhhhhhhhh…I missed that post. WOW!!! Beautiful!
And yes, I pretty much watch all the time with any paper-ish product, and stay in the room with wood.
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I missed that too.
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Ran some tests on a sample piece of Sign Foam that I’ve been saving for a future-yet-unknown project. 
The circles are the engrave tests, in order from left to right.
The cut tests are also in order, left to right. The cutting depths that I noted below were measured as far back into the cut as I could. The cuts were semicircular paths right at the edge of the material but I had to break the insides out by hand since they obviously were not cut completely free.
If anyone has ever used a heat gun to melt/shape polystyrene foam, the texture left behind on this polyurethane foam was pretty similar.
I included a scanned copy of handwritten settings from my notebook for reference.
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“saving for a future-yet-unknown project. ”
…Hello, my name is Suzanne. I am a craft-a-holic… 
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I also save wood, fiberglass and carbon fiber sawdusts (aka: I never sweep the floors in the workshop)… you never know when you might need to scoop some up to thicken some glue. 
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what density was your sign foam?
18lb/cu.ft… The settings note page is labeled at the top but isnt exactly clear.