Etching brass with ferric chloride, What to use as a resist?

[Dan Ashlin]

Im etching some brass shells with ferric chloride, but i'm torn on what to use as a resist. I'[m leaning towards krylon paint, but im thinking that would take forever to take off once the process is over. any suggestions as to what will hold up but not eat up all my labor time in removal?

[Richard Rumancik]

Dan, that is the Holy Grail of etching. Rodne has probably done more etching than most of us and I know he is still searching for something better for a resist. I've done lots of R&D (mostly R) on the topic but there does not seem to be anything that is optimum for laser engraving. Quite honestly, I don't think removal of the "paint" after the etching is the biggest problem. The problems are: 1) getting the resist to adhere well in the first place - not so easy with brass and copper 2) finding a material that will laser off CLEANLY i.e. not leave a residue. 3) finding a material that will laser at high resolution and not chip off leaving rough edges.

Most paints, lacquers, etc will leave a residue of some sort after lasering. You can mechanically abrade after lasering, or use a chemical to remove the residue. Both options run the risk of also removing or compromising the resist. But if you don't remove the residue you will get poor and inconsistent etching.

There are various paint removers and solvents that will remove the paint after etching. I think 3M makes a stripper that isn't too nasty. Brake fluid may work for some products. Of course you have to deal with disposal issues with any chemicals you use.

I have about 15 cans of different paints here which I know won't work - at least, not they way I want. But I don't have the time and resources of Edison . . .

[Dee Gallo]

In a previous life, I was a printmaking major in Art school. We used asphaltum as a resist on metal plates of all kinds and could get very fine detail with acid and a feather (for agitation, silly). Of course, we made our intaglio images by mechanically removing the ground, drawing with a needle. I don't know how it would react to a laser, just thought I'd throw this out there.

BUT, the other thing we used was hairspray (lacquer) for making aquatints... might be something to try? It's clear and easy to remove with no residue.

cheers, dee

[Shawn Conklin]

If you could figure a way to get copy machine toner to stick to the shell you would be set. I use that on flat copper sheets and it worked well. Wipes off with acetone when you are done.

Unfortunatly I think the process only lends itself to flat surfaces where you can iron on the toner.

[Richard Rumancik]

Greg Bednar started a thread recently related to selective plating which used some kind of asphaltum as the resist. I watched the video and it looked like they lasered it successfully, then plated it. So it was used as a plating mask, not an etch mask. It may work as an etch mask as well. But I never figured out exactly from the video and the responses to the thread what was actually used . . .

Here's the thread:
http://www.sawmillcreek.org/showthre...ight=asphaltum

[Dee Gallo]

If anyone wants to try it:
Materials:

1. Asphaltum ground
2. An inexpensive 1" brush
3. Whiting or a substitute cleanser.

Procedure:
The plate must be cleaned of oil, grease and fingerprints that may keep the ground from adhering to the metal. Whiting or a cleanser is used for this purpose. When the plate will accept a smooth film of water we can assume that all contaminates have been removed.
After the plate has been dried with paper towels, brush a thin even coat of asphaltum on the plate. You can either allow the plate to dry on its own or you can place it on the hot plate at a low heat (150 - 200) to speed up the drying.

Asphaltum ground (also known as "hard ground") can be bought at art supply places like Dick Blick... and it IS an etching mask.

Have fun! dee

[Gary Hair]

You can laser asphaltum but it won't come off cleanly in one pass, it will likely take multiple passes. You can increase power and try for faster removal but you will lose detail that way. I found black krylon to work much better and lasered off much cleaner. My customer was etching copper plates with some pretty fine detail and the krylon/laser option worked really well for him. After etching he used mineral spirits or paint remover, not sure which, to remove the krylon.

Gary

[Dan Ashlin]

ASPHALTUM! Thanks Dee! I've been racking my brain to figure out what it was i used when i was in printmaking at school. Thats how i came up with the acid etching idea. Actually using my degree, who knew? I ran some tests and krylon comes off pretty easily with DNA. the only problem is getting it to stick, but i think a few coats will do. Plus, i need to have them done by mid next week, si i guess im running out of time lol. thanks guys for the info!!

[Rodne Gold]

We use polyester based laser friendly vinyl but your major problem is gonna be residues lasers leave behind. You can even use a permanent marker pen as a resist - same problem , laser wont leave totally bare etchable surfaces. I sandblast after lasering to remove residues , hence the resist ALSO has to withstand blasting. I have written a lot about etching on this forum , search for etching or ferric or resist

[Dan Ashlin]

Your info has been a total wealth for me since starting my business, thanks a ton rodne!

[paul mott]

Perhaps I got lucky first time but for copper I use rattle can car paint. I perhaps wrongly assumed that all FeCl3 resistant paint would work, certainly this black primer stuff works beautifully.

Paul.

[Daniel A Thomas]

Beeswax with charcoal or lampblack should work. You might even experiment with jeweler's rouge thinned with alcohol. When applying wax remember to warm the part for even flow.

[Gary Hair]

although your desire to help is commendable, I'm pretty sure this 9 year old thread was long resolved or long forgotten.

[Allen Marlow]

@Gary - If I knew how to PM you on this forum, I would. But I don't, soooo... this will be in the thread...

I came here just today looking for info masking red metals for etching, have read down to the end here, and do not have the impression anything was resolved in the posts from 2010 (eg, no feedback from the OP). And clearly the subject has not been forgotten. My personal opinion is this: if someone has something to contribute, to add to the thread, then that's a good thing (and, as you say, commendable), even if it's years later. It certainly doesn't hurt anything, and I find the beeswax with charcoal idea interesting.

Just as it has taken time for me to respond to you now, it took you some time, however gently, to dismiss @Daniel's efforts. I'm not sure why you did. My (hopefully gentle) comment is this: your response did not add to the thread, and may have in fact stymied Daniel's future contributions.

[Gary Hair]

To be fair, I didn't say the topic was forgotten, just this thread. Several of the people in the thread are no longer active and the OP hasn't posted since 2015 and the fact that the last post in the thread was 2010 it has most certainly been long forgotten by everyone involved - I certainly didn't even realize I had a reply I the thread until I browsed through it to see who had replied. I'll stand by my post.

FYI - if you are a "member" you don't have PM privileges, that requires becoming a paid (donating) contributor. I believe $6.00/year is the minimum for that status.