So I picked up some white, 3/16" Acrylite SG acrylic for some outdoor signs, and in the initial test cuts, the engraves are flaming really bad. I’m testing it with medium proofgrade settings, and I’m getting nervous as I’ve not had any acrylic flame like this before, and acrylic is a regular material for me. The cuts seem to be going ok, but the engraves are super sketchy and I have a lot to engrave for these signs!
I’m using an inline fan, and I think I’m going to try using both the glowforge fan with it to see if that helps, and my air assist appears to be working fine (although I’m going to give it a good cleaning anyways).
Does anyone have any tips for me? These signs require the passthrough and have some large engraves. (I never leave my machine unattended but even standing right there is kinda freaking me out)
Thanks!
Seems pretty simple. From your observations, and their own data:
Flammability
It’s a combustible thermoplastic. Precautions should be taken to protect this material from flames and high heat sources.
… I wouldn’t consider it suitable for laser.
Regular acrylic does not flame at all when engraving.
I read that, but all acrylic is flammable. However, I did just realize that this is extruded and not cast. I was looking for cast when I purchased this too, I’m not sure how I managed that one. 
It certainly is, but neither cast nor extruded “regular” acrylics I’ve bought from GF, Inventables, and multiple Amazon sources flame while engraving. I want to say not while cutting either - I cut (and engraved) thousands of ear savers and don’t recall seeing any flame.
Hmm lots of thermoplastics out there, is this PMMA? If not, all bets are off.
When I read" flammable", I didn’t think it meant “more flammable than other acrylic”. It cuts just fine, but I’ve used all kinds of acrylics too with no flames like this.
I searched the forums for this specific material and found nothing…here’s your warning for anyone that is thinking about this stuff.
WARNING, engraves flame really bad!
I think I may try wetting the paper mask and seeing what happens. I am already behind on this project and it’s a lot of material to waste. I want to find a way for this to work.
I thought it was…but now I’m doing a bunch more researching…
Well, for what it’s worth…I figured it out, but don’t understand. I usually engrave with a higher focus height for a smoother engrave, but that’s what was causing the flames. I’ve been doing a bunch of testing today, including spraying the mask with water (which helped and didn’t appear to affect the engrave), and on one of the tests, I went back to exact focal height, and the flaming disappeared. Yay for testing!
Just thought I’d share my findings 
Carry on.
Thanks for reporting back. Very strange…
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