Just because it says its stainless doesn't mean anything

Here’s your PSA for things aren’t always what they seem or aren’t always what they are sold as. I picked up around 15 really cheap (yes key word there) business card cases from Amazon to try out 3 different dry moly sprays. For science and the great good of the community you know. Prepped two of the card holders weeks ago (testing long cure time versus quick cure time) while waiting for the third dry moly to arrive. Got the design loaded into the GFUI, laid the holder on the tray, made my settings, and waited for the “making magic” button to light up. Once it did it took off doing it’s thing and was making a wonderful result. Then I stepped away right before it was finished to open a tab on the laptop (photo so I’m not labeled as “that guy who left the room”) and when I looked back right as it was finishing I saw my once flat card holder was now buckled open.

On first glance I assumed the fan was just THAT powerful, then I noticed nothing was moving or flapping. Once the print finished I opened the lid and saw that it had actually warped the metal. When I opened the card holder I also saw that it was apparently warm enough to “stamp” the metal too. This is a thin gauge metal card holder but the gauge, especially for stainless, shouldn’t have been that thin.

So lesson learned for everyone, ALWAYS watch your materials and never trust everything that isn’t from a trusted materials vendor.

Tried a second one and shrank the image and the same thing happened. Now time to find something else to test these three dry molys on since this seems like a bust.

You’ll notice there is a different texture in the metal, polished and brushed, I thought that could have been the issue so I tried again keeping it in the brushed area. Same results.



Thanks for the reminder!

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Why does it look like it’s actually engraved into the metal?

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That’s the magical question, and part of the reason I stopped for the night.

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These are the mysterious “stainless steel” card holders. I bought them for $5…should have known then.

Well there is that video of a guy in the UK proving you can engrave stainless with a 40W co2 laser. I’m sure some googling will find it.

Otherwise, @dan can probably tell us what metals a co2 laser of this power can engrave? Nickel coated Tin?

Well…then there’s this…surprised the heck outta me!


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@Xabbess I saw that not long before/after I ordered the molys for testing and thought about doing a “dry” test too. I probably will. I just gave up for the night since it’s late, my real job beckons, and the mystery metal deserves 100% attention just in case.

:beers: To science, lasers, and the “oh the what the heck let’s try it and find out” mentality


Just because the laser can mark it doesn’t mean it isn’t stainless steel. There are hundreds of different iron alloys that fall under the name stainless steel. Stainless can be manufactured down to foil thicknesses, so that isn’t a good indicator of material either.

We have seen several users show that iron alloys can be marked or even engraved with a 40 or 45 watt laser. Iron alloys and titanium seem to be the most receptive to lower power laser engraving.

This is about the behavior I would expect from heating a thin metal sheet in the manner the laser would heat it. Since the metal expands as it heats, the expansion has to go somewhere, and the metal doesn’t always return to its former shape because of the way the metal cools.

I suspect this is a Chinese version of a 300 series steel that gets harder as it gets worked, so the actions of bending it to shape will give it its strength. Bending the cover back to shape should resolve the issue, though you may have to overbend to get it where you want it.


Fact of it is, with iron chromium metal there is stainless, Stainless, and STAINLESS.
A quick check with a magnet will show how far down the stainless line it is.
Even the magnetic versions, however, will still be corrosion resistant to a degree.

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I’m not too much of an expert - I’ve read a lot online and experimented, but since we don’t carry PG materials, I don’t recall any testing we’ve done for official support.

This is interesting. I’ve done a few things on thin metal (can’t remember if it was stainless) and had notice is warped the metal just a bit and it appeared “stamped” where the laser hit it. It wasn’t nearly to this extent though.

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Thanks for your research and sharing your experience. Cheap “stainless steel” flasks also warp under some conditions. Some suggest filling them with water before engraving, but the possibility of a leak inside my Glowforge prevents me from trying that solution.

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When I click that link it says i dont have access to view that topic? Is there more topics that new users cant see?

I don’t have access either and I am not a new user. I suspect it has been marked private for some reason.

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Well now I am curious haha. Thanks for the help.

Before my laser arrived, I had stocked up on samples from various suppliers, so when it came I did a whole bunch of testing right off the bat. I was having some trouble getting a good mark on the 304 Stainless with T22 Green Mirror finish from Rimex Metals. I figured I could just do a bunch of high-power passes, since the laser wouldn’t do anything to the stainless steel… but I didn’t think about the heat buildup!



That’s crazy. I only did one pass so I’d hate to see what would happen on multiple. :skull_and_crossbones:

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Sorry…I moved it…try it again; An interesting oversight

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