Thanks for the input. Would pink board (used as building insulation) fall into the danger zone? I’d assume it’s the same kind of foam.
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Just FYI. in a previous project I decided for some reason that I wanted exactly 4 mm plywood, and the first piece I found was labelled marine Plywood. I think this meant that it was capable of being bent to make the curved surfaces of a boat.
I cut it on an Epilog laser, and discovered that this particular type achieved that by having the middle ply made out of something that looked like rubber. Major smoke and fire. This may not be true of all plywood labelled marine.
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I believe the ‘marine’ part of ‘marine plywood’ refers to the water-resistant adhesives they use (vs. bindability)… would explain the nasty smoke.
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1000% correct
Same for exterior grade plywood. Not as nasty as the Marine grade stuff, but still worth noting.
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Yep, pink foam is made of the same stuff as blue foam. From what I understand, the only difference between the pink and blue foam board (other than the color haha) is that they’re manufactured by different companies 
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Good to know. Guess I’ll continue cutting foam under the car port with a hot wire. Thanks for the info.
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I’m interested in a substitute for the Pink/Blue foam. I had plans to etch faux tombstones. The limited size of the passthrough, kind of dashed those hopes anyway.
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You could cut/etch on any 1/4" material, attach that to the foam for thickness, and then paint it.
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There are HDU (high-density urethane) products that are laser-safe. This type of foam is used a lot in signage and prop-building, It would probably work great for faux tombstones. I just requested a sample of Corafoam HDU from Duna to try out.
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I spoke to someone from Duna today about getting a sample of Corafoam. He said they recommend it be cut on a CNC router but it definitely can be worked on a laser. He said Epilog has done demos of cutting Corafoam at trade shows. But then he said something to the effect of “our stuff probably gives of toxic fumes too so you will want to vent/filter it”. That was a little bit of a mixed message. I have some samples on the way to test both on my CNC router and the Glowforge.
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I’m going to keep my eye out for something I can source locally as well. I hate paying shipping costs!
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I mentioned a MA-based distributor I had talked to about other brands of HDU. He said they had almost become a distributor for Corafoam. If I like it, I’ll check around for other possible local sources.
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I have some think fiberglass sheets that come 10x10 inches. I was hoping to try cutting that with the lasers. I will be cautious.
What about Carbon Fiber sheets? Any issue with that, or is that the resin issue as well?
Eric
Would it be safe to cut polyethylene?
Stuff named ‘POLY something’ are varied. Best to get an MSDS from the maker of the item.
Lacking that, a search for “Polyethylene MSDS” should give you at least a general definition of the product.
In general you are looking for nasty or corrosive sub products of burning, but there are other concerns.
You also have to consider end product usage. Is is going to store food? Are small children going to be drooling on it? And so forth.
This is true with woods as well as plastics.
Hi.
Thanks for the info. I checked polyethylene on Wikipedia and found that it doesn’t contain any chlorine. I needed to cut out a stencil, and it worked great.
Have a nice evening.
Gregory
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There’s lots of kinds of polyethylene. From what I can gather, generally people have the best luck with thin stuff. Thicker and/or heavier stuff, results are apparently mixed like cutting HDPE tends to make a melty mess.
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Have been searching this forum as well as the internet but either missed, or searched poorly. Not finding much on etching cured gypsum products like plaster of paris or hydrocal. A few videos out there. A few photo references, but nothing definitive on whether it is a good idea or not.
Any recommendations? Apologies if I missed this somehow.
Thanks,
Steve
I had not seen anyone try that, interesting idea!
One of the properties of Calcium Sulphate (aka gysum) is that it is quite stable at very high temperatures. Like a few thousand degrees F high. That is one reason it gets used in most casting investment mixes. I would guess (only a guess) that it is safe but messy.
If you could break it down you would get SO2 which is a pretty noxious gas, but I doubt you will get there.
You might need to be concerned about other additives though, so check the MSDS for your specific product.
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Thanks for your reply. Will certainly look closer at MSDSs before attempting. Nothing “jumps out” to my eyes with US Gypsum Hydrocal: https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/sds/usg-hydrocal-white-gypsum-cement-sds-en-52000000092.pdf
But I will read more thoroughly. Just wondered if anyone had tried and if there was any feedback.