Laser engraving -question

[Thomas_H]

Hi,
I tried to get a black powdercoated Hammond 1590A laser engraved.

This worked fine in the way that the laser has cut sharp graphics into the paint.
But for some reason the lines are not silver shining as you would expect but dull grey.
Yes, the laser has cut in the aluminium. If you use a sharp needle you can scratch throug the dull surface and get silverish aluminium.

Any idea what I have done wrong?

[jkokura]

You haven't done anything wrong I don't think.

Dave did an enclosure for me, of a green hammertone enclosure from PPP. It had a simliar issue in that the etch was nice and clean, but the metal underneath was green tinted still. I've seen some of Dave's boxes that have similar issues.

I think what it comes down to is both the prep of the enclosure and the method to which the paint adheres to the enclosure. It sounds to me like the Hammond factory paint does this process to your enclosure that keeps your laser from etching right through.

You could try using some rubbing alcohol and trying to see if that cleans it up. If that doesn't work, and you don't mind potentially ruining the enclosure, you could step up to Acetone. Warning - acetone may actually remove the powdercoating you want left alone, as well as the residue you want to remove.

Jacob

[pickdropper]

You didn't do anything wrong.  Jacob is right that there are times where you just can't get to the raw metal.  A few comments/suggestions:

1.)  Boxes are generally not shiny underneath the powder coat.  In fact, I suspect having them shiny would hurt adhesion.  When you etch, you just wait and see what's underneath.

2.)  Some powder coats (particularly black) often take more than one pass to get everything off.  Often, if you etch once, it's dirty.  A second (sometimes 3rd) pass removes more of the paint residue.

3.)  I nearly always clean the top of the surface with flux remover after I etch.  That helps clean things off, but doesn't remove the remaining clear coat.  If I am doing more than one pass on the engraver, I wipe off the top with flux remover in between passes.  If you don't have flux remover, you can use alcohol, but I prefer flux remover.  Acetone is absolutely a last resort.  I've used it, but it immediately started pulling off the powder coat itself.

4.)  There have been boxes that I got to look more polished by scrubbing with flux remover (or alcohol) and a toothbrush.  I've actually used MAAS metal polish as well, but I've only found that to work well if I have larger exposed metal areas.

5.)  As you etch more boxes, you'll find that some colors just don't etch well.  Some etch fine but don't offer enough contrast.  The etching can also vary by the vendor selling the boxes.  There are a bunch of variables, so a bit of experimentation helps.

I etched a Hammond box with stock finish for the first Andromeda build.  I was able to etch directly to the box, but maybe there is something different with one from the batch you have.

[Thomas_H]

Thank you guys, you are keeping my spirits up :-)

I will do another one and take some flux remover to the engraving shop with me.

I was thinking that maybe the power of the laser was too high and the flaming that occoured would have done some immediate oxidation to the aluminium.

[Matt]

You can also try baking soda / water.  Make a paste with it and scrub the area with a toothbrush.  Works great on tarnished surfaces, might work on this.

[pickdropper]

Thank you guys, you are keeping my spirits up :-)

I will do another one and take some flux remover to the engraving shop with me.

I was thinking that maybe the power of the laser was too high and the flaming that occoured would have done some immediate oxidation to the aluminium.

Hmm, did you see an open flame?  That isn't really common with etching the enclosures.  Open flame is more common with vector cutting operations.

Depending on the power of the laser, it is possible that it was set too high.  But If the image is sharp, then that is unlikely to be the problem.

Keep at it, I am sure it is a solvable problem.

[jkokura]

You can also try baking soda / water.  Make a paste with it and scrub the area with a toothbrush.  Works great on tarnished surfaces, might work on this.

Also good for your teeth.

Jacob

[Matt]

Excellent point!

Also a good antacid but its nasty.