[esealpha]

Just found this forum so hopefully someone can shed some light on my problem.

We've had a GCC C180 30W laser engraver for a several months now. We've been slowly working through engraving and engraving/cutting mostly plastic and phenolic legend plates. We've also done some aluminum legend plates too. We finally found that using CerMark LMM-6018 tape yielded the results we wanted giving us a nice black mark.

At some point that stopped working. I remember I engraved one of our delivery drivers aluminum clipboard with their name and produced a nice solid black mark. A couple hours later (on the same day) I tried doing another driver's aluminum clipboard and it also produced a nice black mark...which I quickly rubbed right off with a damp rag. What was left was a VERY low contrast mark. The black came off like it was dust.

So I'm not sure what happened here but this has persisted with aluminum legend plates that we had etched just fine in the past. They now seem to no longer work. Nothing seems to mark these plates anymore. What's even more confounding is that there are a couple different aluminum plates that I HAVE been able to etch (with the tape). I just don't know enough about the laser or the aluminum to know what to try next.

As an FYI, these are similar to the legend plates we're trying to do.

[OldEngraver]

I wasn't aware that you could use Cermark on aluminium .If so, I would say that it would need much more power than 30 watts. The fact that the black mark that you achieved comes off easily is a good indication of that.

[esealpha]

Well, we tried it as a shot in the dark. We tried the spray first. The LMM 14. But it wouldn't touch the anodized aluminum. We also ordered some of the LMM 6018 tape to try. And it worked. We've made dozens of marks on the aluminum legend plates similar to the one in my pic. And no amount of scrubbing would remove them. We tried the tape based on this from thermark.com...

LMM6904, a CerMark™ product, is a product for creating black marks on anodized aluminum. LMM6904 has been specially designed to create consistent marks on anodized surfaces despite the known variation in the quality of the anodization. In general, however, TherMark recommends LMM6018.LF tape for marking on anodized aluminum, as it creates a darker and more uniform mark than LMM6904.

So the tape worked for a while. Then one day, it just stopped working. I figured it was probably some different coating on the aluminum or something.

[OldEngraver]

Well, I will give that a shot myself! Always good to have another string to your bow!