Etching painting aluminum or other metals

[dave hensley]

Hi,

Is it safe to paint and then etch metals like aluminum and copper? I've read about the possibility of the laser bouncing back off the metal. If that's true, how does that not happen when marking metal?

What I am hoping I can do is paint various sheet metals and then etch out a design or artwork on the piece. I'd appreciate any tips on doing this if it's possible.

Thanks!

[Dee Gallo]

Dave, I've taken common aluminum baking pan lids, sprayed them with automotive paint and engraved with no problems. They come out really nicely. You can also use primer underneath and get a two-toned effect.

cheers, dee

[Richard Rumancik]

Dave, the metal won't be all that shiny when it has the paint over it. Same goes when using Cermark to mark metal. But even if it was somewhat refective, with the lower power lasers the risk of bouncing the beam back into the tube is not very substantial as it is in metal-cutting lasers. I contacted Synrad about this many years ago and they did not seem to be especially concerned with reflections on low-power lasers.

Your challenge will be to find a paint that (a) adheres well (b) lasers off cleanly without residue (c) resists the chemicals and (d) strips off easily at the end. Let us know what you find. How deep are you planning to etch?

[dave hensley]

Thanks Dee! :D

Richard - I expect I'll only be putting two coats of paint on, but have no idea how thick a layer of paint is. If I really like the process, then I may try multiple layers of varying colors. In some places, I do want the metal to show through. Sounds likes it's at least safe for me to experiment with this, so I'll give it a try. I am sure my attempts will not be on par with the rest of the work you folks do, but I'll post back when I've run a few jobs. Thanks!

[Mike Null]

Dave

I buy lacquered brass and aluminum for engraving all the time. All commercial shops do this daily.

[Dee Gallo]

Here is a photo of an aluminum pan lid which was painted with red primer then blue metallic auto paint, two coats of each. I did a lot of testing and found that you cannot laser through primer, so you can get interesting effects knowing that. The red, white and black primers all work well. If you don't use primer, you get plain metal showing, which is also nice looking.

[Dan Hintz]

Dave, the metal won't be all that shiny when it has the paint over it. Same goes when using Cermark to mark metal. But even if it was somewhat refective, with the lower power lasers the risk of bouncing the beam back into the tube is not very substantial as it is in metal-cutting lasers. I contacted Synrad about this many years ago and they did not seem to be especially concerned with reflections on low-power lasers.
To add to Richard's comments... the issue shows up on high-powered lasers as you are typically creating molten pools of metal. Molten metal usually means highly reflective, so you're creating a moving mirror right at the focal point. That's bad. Not an issue with our low-power stuff.

[dave hensley]

Thanks Mike! I'll look into that option

Dee, that looks great! And a very helpful tip about the primer... can definitely use that. :)

Dan - that makes sense. Wish I could remember where I had read about this issue and what exactly it was referring to.

Thanks again everyone for the help!!

[Chuck Stone]

I did a lot of testing and found that you cannot laser through primer, so you can get interesting effects knowing that. The red, white and black primers all work well. If you don't use primer, you get plain metal showing, which is also nice looking.

I found that out the hard way .. used primer and a metal engine enamel on an old saw blade.
Got a beautiful paint job, the primer really helps. But then I tried to get back to bare metal
with the laser .. no go!
So .. I either skip the primer and maybe the paint sticks.. maybe not..
or I get a nice paint job and the laser only gets me back to white primer.

[dave hensley]

Does anyone know why the laser does not remove the primer?

[Richard Rumancik]

Dave, I realize that I misunderstood your objective - when you said "etch" I had "chemical etch" in my head, not "laser etch". So my comments were a bit off topic. I have been experimenting with chemical and electrolytic etching over the years and I suppose that's why I read something into your post that was not intended.

[Dee Gallo]

Possibly they add chalk, zinc or titanium to the paint to make it work as a primer. Whatever it is, it seems to repel laser beams. Is there a chemist in the house?

:) dee

[Dan Hintz]

I could swear I answered that question in an earlier post... :-/ Now I hafta find it... but Dee is on the right track.

[Mike Null]

I don't have any experience trying to laser a primed surface but I do some powder coated metals and have no real problem except that it frequently takes and extra cleanup pass. Powder coating is not quite uniform in thickness thus the need for the extra pass.

The lacquered brass, steel and aluminum from engraving suppliers has no discernible primer.

[dave hensley]

Possibly they add chalk, zinc or titanium to the paint to make it work as a primer. Whatever it is, it seems to repel laser beams. Is there a chemist in the house?

:) dee

That's interesting. My mind is whirling with ideas. I wonder if you could tint white primer and then use that as a "color base"?? Seems like it could work if one did not add too much color that negated the "laser-resisting" properties of the primer.

[dave hensley]

Dave, I realize that I misunderstood your objective - when you said "etch" I had "chemical etch" in my head, not "laser etch". So my comments were a bit off topic. I have been experimenting with chemical and electrolytic etching over the years and I suppose that's why I read something into your post that was not intended.

No problem Richard. :)

[James Foster]

Here is a photo of an aluminum pan lid which was painted with red primer then blue metallic auto paint, two coats of each. I did a lot of testing and found that you cannot laser through primer, so you can get interesting effects knowing that. The red, white and black primers all work well. If you don't use primer, you get plain metal showing, which is also nice looking.

Hello Dee,
What type of "primer" did you use? I frequently use an enamel type primer and I'm able to engrave through it if need be.

-James

[Dee Gallo]

Hello Dee,
What type of "primer" did you use? I frequently use an enamel type primer and I'm able to engrave through it if need be.

-James

Hi James, and welcome to the Creek!

I use auto primer, as it is very durable, sticks to metal well and is compatible with the auto paint I use on top of it. You can also sand it if you get a blip once in a while. I like to have something that can go through the dishwasher (carwash) even though these do not get put in the oven.

cheers, dee

[James Foster]

Hi James, and welcome to the Creek!

I use auto primer, as it is very durable, sticks to metal well and is compatible with the auto paint I use on top of it. You can also sand it if you get a blip once in a while. I like to have something that can go through the dishwasher (carwash) even though these do not get put in the oven.

cheers, dee
I must of misunderstood you. I thought you said that your laser can not cut through primer.

-James

[Dee Gallo]

I must of misunderstood you. I thought you said that your laser can not cut through primer.

-James

No, you had it right - my laser will engrave through the paint layer to expose the primer layer and not expose the bare metal. I have a 30w Epilog - what are you using? Maybe people with more power can blast through primer, I don't know.

BTW- it is a good idea to add your machine info to your signature so people know what you are dealing with.

[James Foster]

No, you had it right - my laser will engrave through the paint layer to expose the primer layer and not expose the bare metal. I have a 30w Epilog - what are you using? Maybe people with more power can blast through primer, I don't know.

BTW- it is a good idea to add your machine info to your signature so people know what you are dealing with.

Have you ever tried engraving on acrylic using a colored primer, wondering if you would be able to break through? I got excited there for a moment, as I would like to find a primer that you can not engrave through. I missed the key point, that your using it on metal.

I have been experimenting lately with using different layers of colored paint. I'm trying to learn step engraving.

I have two LG500 60watt Chinese lasers. I'm using both Laser cut 5.0 & 5.3. I really like the lasers, but, the Laser cut software is a little inferior. The good news is, that I do most if all creation in other software and Laser cut is "control" only.

[Dee Gallo]

Have you ever tried engraving on acrylic using a colored primer, wondering if you would be able to break through? I got excited there for a moment, as I would like to find a primer that you can not engrave through. I missed the key point, that your using it on metal.

I have been experimenting lately with using different layers of colored paint. I'm trying to learn step engraving.

I have two LG500 60watt Chinese lasers. I'm using both Laser cut 5.0 & 5.3. I really like the lasers, but, the Laser cut software is a little inferior. The good news is, that I do most if all creation in other software and Laser cut is "control" only.

That would be a good experiment to do - but no, I've never tried it. Aluminum transfers the heat differently from all other substrates, so maybe that has something to do with it too. I would guess that the auto primers would eat away acrylic, though.

I had a Chinese laser at one time and found LaserCut to be just plain awful. That was one of the reasons I sold that laser. I'm not very tolerant of bad software.