Got new anodized alluminum knife handle that c02 laser WILL NOT mark

We are a knife manufacturer and we have etched knives with handles made of EXACTLY the same aluminum for years now without an issue.

We released a few new knives this year, 4 with black anodized aluminum, 4 with gold anodized aluminum. We put the 4 black in the c02 and we get the perfect white etch we have always gotten. We put any of the 4 gold in the same laser and I'm not exaggerating when I say, it doesn't even approach marking it. We have gotten gold aluminum for handles from the same source and not had this problem.

Here's where it gets super confusing. I moved the gold ones to a Fiber Laser and accomplished SOME sort of an actual mark. It's not super clear but at the PERFECT settings you can see and feel it so it cut into the metal.

Has anyone else experienced this? What causes it? Is there anyway to get these to etch? We really don't want to use Thermark because it's inconsistent and messy.

Just spoke with another company who has had the same problem with certain aluminum's including gold Yeti cups. They have not found a work-around. I considered laser color foil but its too time consuming for the amount of knives we would have to do it for.

Really hope someone has an idea. We have a ton of these knives and need to figure it out.

First off I’m surprised that CO2 would cut a reflective material like that.
If you test cut something from an older batch, and it cuts ok, then something has changed in the material. If it doesn’t cut then something changed in the machine.


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Thanks for the reply! We've always used the C02 to mark all of our anodized aluminum. As far as I know that's a common use for C02s.

I have test cut old gold alum and it worked as it always has. I figured something changed in the metal but there's gotta be a way to get it to etch....

Have you tried a mask on them to see if the gold is reflecting the laser

what do you mean by mask?

Try a damp piece of newsprint

The FIRST order for the knives in question is for 10,000 and that's just the first one. We can't use anything like that because its gonna burn into it and then we have to peel away the excess. We just don't have the help or the time to do that,

This would not help the second batch… but can you go back to the knife supplier and ask them what has changed? I often run into issues cutting 6mm plywood from batch to batch. Glue layers have a big effect on lasers. Glue is not organic and doesn’t burn, so it acts as a shield in the wood, also the more layers the harder it is to cut. About the only thing you can do is add more power. Multiple passes and slowing the cut doesn’t always result in a nice clean cut, but it’s worth a try.


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Much appreciated. I've tried multiple passes and changing speed and power. Can't get anything. Part of me is starting to feel like there is not a solution but at the same time, this is metal and we're shooting them with lasers, we gotta be able to figure this out lol. I know there's someone on here with a stroke of genius just waiting to comment.

If you work with aluminum and haven't had this problem then you're more than likely going to experience it soon.

The paper just falls off no burning in it just keeps the beam from reflecting

Hmm. Super interesting. I have not heard of that trick. Will try soon and report back. Thank you so much,

I just tried and it didn't make a difference. I may not be doing it correctly though. I wet a piece of news paper and laid it on top the knife handle. Should I wrap it tight? Is there a trick I'm missing?