I often times finish my unfinished woods with Polycrylic after engraving and cutting. I have never finished them first with Polycrylic and then engraved or cut. I’m too afraid of causing a fire or damaging the machine. I was wondering if it would be safe for me to finish the wood boards with Polycrylic and then cut and engrave them after they have dried. I have included pictures of the exact product I use for finishing.
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It’s always a good idea to search for the Safety Data Sheet when in doubt.
I looked it up and here are the hazards associated with burning it. I would not hesitate to laser it (with good ventilation) based on this:
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At the MWR IN Hawaii, we used to pre-spray the wood because the a light sandin took off all the residue. I think we used a lacquer spray.
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Do you know the brand?
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So, this would be safe for the machine and my health based on this information?
Not off the top of my head it was back in 2002-2004. Probably delft lacquer spray. I think we also used watch wipe-on varnish. Both create thin skins and can protect and sand off easily.
Check out #4:
I wouldn’t want to inhale the exhaust but if you have it directed safely outside you should be good to go.
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I use the brush-on version all of the time to make my own “Proof Grade” material.
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This.
It’s the only clear finish I use, mostly on PureBond ply from THD and Baltic Birch from Rockler. Takes many light coats to get a nice glass-hard finish on BB, but one is usually enough on PureBond.
Not a fan of the spray.
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I just looked at #4 but I am not sure if that applies to Polycrylic. Did I miss something?
It’s all about what materials are dangerous, why, and a list of materials that you might be interested in. It may not cover polycrylic directly, but if you internalize everything in #4, you won’t have to wonder about new materials as they come to mind – you’ll have all the knowledge you need to make an informed decision on your own 
Also, all the advice you’ve already gotten is spot-on.
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So I just did a test and it didn’t flare up at all. No fire thankfully. The smell is pretty strong though. I have the exhaust directly going to the outside of my house. I can smell it some on the other side of the house, where as standard GF proofgrade barely had a smell at all. This stuff smells slightly like burned toast. I will just make a point of not being outside when I am cutting.
That is a very good choice. Best to be watching the laser at all times.
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