Trouble with CerMark and brass plate...

[Nick Syrax]

I am trying to mark this brass plate and no matter what settings I use, the black comes off leaving it looking faintly etched, as seen in the photo below here are the speed/power settings I have used on my Epilog Zing24 40w laser using Corel X5 with the CerMark mixed 1to1 with denatured alcohol:

2/100 4/100 10/100 15/100 20/100 25/100
30/100 35/100 40/100 45/100 50/100
Any help would be GREATLY appreciated!

http://www.flickr.com/photos/36047273@N06/5855825238/

[Gary Hair]

It probably has a clear coat on it and Cermark must be applied to bare metal. Remove the coating with acetone and it should work fine. Try full power and about 40 speed as a starting point. Ferro recommends 100% power and speed the same as the wattage of your laser. Mine is 30 watts and I use 10%, so it's obviously just a starting point. My guess is that you'll use between 10% and 30%.

As a side note - you can thin the Cermark about 10 - 1, at 1 - 1 you are using way too much! If you can't see the metal through the coating then you are applying it too thick. Test it on some stainless, you'll be amazed at just how little Cermark you need to get a consistent mark. A thinner coating will also mean you can use more speed and get the same results.

Gary

[Richard Rumancik]

. . . If you can't see the metal through the coating then you are applying it too thick. . .

Hmmm . . .I'd say that if you can see metal then it won't work as well. If you are seeing any shiny metal through the Cermark then you won't get a very dense mark. If your Cermark coverage is 90% then you will not be able to get 100% black and the edges will be rougher. The manufacturers recommend a lower dilution rate. I think 3 parts DNA to 1 part Cermark works well in an airbrush.

If there is a clearcoat and the laser did not take it off on the first attempt then I wonder if acetone will take it off. Sometimes rather than remove ALL the clear coat you can laser the clearcoat away, apply Cermark, and re-laser. But you need to be able to have exact registration to do a second pass. For one-offs you could apply by brush while the plate is fixtured firmly to a board clamped to table. If you misregister the plate .002" it will show.

If you did not see any evidence of the laser removing the clearcoat then it might be difficult to get it off using other means. Also note that if you remove it all, the plate will tarnish (that's why it is there in the first place.)

Edit: Based on the photo it looks like there is clearcoat. Maybe if you do first pass at high power/slow speed you can ablate all the clearcoat. Clean residue and apply Cermark, then remark. Not a good process for high production, however.

Brass is hard to mark at the best of times. It conducts the heat away faster than stainless.

[Mike Null]

I'm with Gary on using very thin coats but I also agree that brass is very difficult. So much that I don't attempt it anymore.

[David Lord]

I occasionally mark brass trophy plates, and have achieved success by using a fine graining block first. This obviously dulls a mirror finish to the plate but it works for me.
David

[David Hartstone]

Here is a suggested way to do brass plates. We have used this method with much more success than using Cermark.

1: Mask the plate with sand etch material.
2: Engrave or vector cut what is to be marked
3: Sand etch as per glass - depth can be achieved if that is the desired result
4: Darken with a brass darkening chemical and wash off; the result is always variable so apply a black rub n buff to even out any light spots.
5: Remove the mask and reveal a sensational result.
6: The brass can then be covered with a clear gloss to prevent tarnishing.

Epilog Helix 50w, Kern HSE 150W, Electrox YAG, Sublimation, Sand etching