Plexiglas?

Beyond the Manual
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I have a large piece of material labeled “Plexiglas ® MC Acrylic Sheet”. But then there’s a big warning label saying it’s a combustible thermoplastic and burns vigorously with intense heat. It says it can be saw cut, drilled, cemented, or routed. But the rest of the label is blurry and unreadable.

I had been planning to cut a 12 x 12 inch square to make into a sticky mat to hold down super thin wood sheets, cardstock, and stuff like that. But I obviously don’t want to use it if it’s very, very burn-y or unsafe to stick in the laser cutter. But if it’s acrylic like it says, shouldn’t it be safe?

Ideally, I want something safe to stick in there but as resilient as possible. I’d like to use the mat a lot, after all. Any other material suggestions that would work much better?

Maybe I should just buy the $85 one not-made-by-me that got posted a while ago…

Edit: I think part of the label is saying something about first aid when exposed to vapors from heated product, so I should probably just back away slowly…

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Just use some cheap plywood. Whatever you use for a mat is going to get cut up. You’ll care a lot less if you spent a dollar on a section of cheap wood than if you cut up an expensive sheet of acrylic or a specialty mat. :slightly_smiling_face:

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Nah it’s likely fine for lasering as long as it doesn’t say “Lexan”. It’s either going to be really nice (cast) or okay (extruded).

But acrylic isn’t what I’d use for a sacrificial board. Use BB.

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I was thinking…I wonder if a sheet of boro wouldn’t be the longest lasting mat? At really low paper cutting power levels, it probably wouldn’t even get nicked. (Krylonned of course.)

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I tried googling ‘boro’. Internet says its either a japanese textile or a formula one team. Sometimes google is not helpful. What’s boro?

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I’ve been eyeing my borosilicate glass UM2 build plate, thinking about etching the underside with a grid.

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Oh hey, look at that. Problem solved the second I asked it.

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Formula one team…they can really scramble and get out of the way of the beam. :innocent::smile:

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Thank you kindly. BB I have in spades. Trying a piece of that out now.

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Sorry, new here. What’s BB?

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Baltic Birch if I’m not mistaken

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This is what I interpreted as, so I certainly hope you are correct :blush:

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Correct. Baltic Birch (BB) plywood is not the same as Birch plywood from the big box stores though. But it’s the laser user’s go-to material of choice (although PG Draftboard is good too :slight_smile:️).

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To answer the original question, yes the plexiglas is acrylic (PMMA). Yes, all acrylics have those properties (combustible, etc) and yes, despite those properties acrylic is deemed as “laser safe”.

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If I’m not mistaken, acrylic is only flammable if one holds a flame to a large enough area of it for long enough time. Usually, the laser zips across (and quickly through) the material fast enough such that it only smokes a little.

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Just to update for posterity, and anyone else who is trying the same thing in the future, @jamesdhatch was spot on. Baltic Birch Ply works great! I painted it with acrylic paint to keep it separate from all the other pieces floating around my room, but it’s perfect.

@Jules is totally right – it gets scorched and a little ugly, so the cheaper route is definitely worth while.

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