We’re engraving acrylic paint that is poured over simple household aluminum foil. Is it safe for the laser to engrave all the paint away and hit / reveal the foil below? Thanks!
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it should be just fine.
People engrave anodized aluminum all the time.
I’d just watch it to be sure there’s no flames or anything.
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Sounds intriguing! I’d love to see what you are making.
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The only issue I’m aware of when putting metal in a laser is having the laser reflected back which can cause damage to the laser. I’ve engraved anodized aluminum with no problems.
I believe as long as the metal surface is not highly reflective there should be no problem.
Hopefully, we’ll get to see what you’re making 
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Lump me in with the folks who want to see if it works out. So please post some examples or cautionary tales whichever way it works out.
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Reflective of laser light wavelengths is the key thing here. Chrome and copper definitely will reflect, so don’t use them. Aluminum absorbs that wavelength as I understand things so it should be fine, albeit hot.
Caveat laser. If in doubt ask google, or the forum or support or someone. Don’t trust my ramblings.
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First, different materials reflect different wavelengths at different rates. Copper, for example, is the most reflective material for the 10.6um wavelength of our CO2 laser. Aluminum may as well be wood for as little as it reflects.
Second - anyone who’s played with focus height knows there is a very small region where the beam can be effective. Any reflection is not going to be focused to the point of causing damage. If it was that easy to effectively manipulate the beam, they wouldn’t be using precise optical and mechanical components to do it…
Edit: or what evansd2 said!
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@evansd2 and @eflyguy - thank you for the additional clarification. I was not trying to say aluminum should not be used, as I stated I’ve used it in my GF. My comment was just a general statement which you both stated far more clearly than I about reflective concerns of different metals in a laser.
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I’ve used aluminum foil in my forge a number of times, usually to keep small parts from falling through the crumb tray after cutting, and once to protect an area I wanted to keep from etching / cutting (there was a stray mark in my file, and I didn’t want to lose positioning so I couldn’t edit it out). It didn’t cause any problems.
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I’ve engraved through both acrylic paint and whatever rattle-can spray-paint is made of using different base materials, although not aluminum foil, and I’m still here as is my forge.
Thanks everyone! Very helpful. I’ll upload a picture soon. The story goes: my friend did some “pour painting” over aluminum foil so it wouldn’t absorb into the substrate. The result is very cool and he had the idea to etch the pain off and reveal the foil below (or partially). Looks great. Photo coming.
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Still waiting patiently…
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