I needed to etch a brass tag and needed a resist. I tried about 4 kinds of spray paint but they all left behind a film that made the ferric chloride etch inconsistently. I also tried polyester packaging tape but that did not burn off cleanly either. Finally, with deadline looming, I just used some blue painters tape. I thought it might hold up for at least a shallow etch. In reality it worked great!
Here is the finished product, a custom post-it note caddy.
I love it! I’ve got etching apparatus here and still haven’t tried this. Definitely beats the ol’ film process.
Funny note: on my first read I thought it said A is for Anarchist.
Archivists are the anti-anarchists!
Well crap I guess I have to buy more materials and chemicals now!
The etching process is fun. Here are a few things I found out. Some the hard way.
Plate prep: Rub with OO synthetic steel wool this helps the paint stick.
Paint: Krylon Ultramaxx Satin black. Yes, Satin. I bought a can of Gloss once. Mistake. One light coat, just enough for flowout. Bake at low temp. 100 degrees F(Frankenstein) for 20 min, or cure in a warm spot overnight.
The Burn: 2 passes as low a power as you can go and still remove what looks like 90% on the first pass. The second will get most of the rest.
Prep for etchant: Rub lightly with steel wool. Up/down Left/Right and diagonally. This cleans whatever film remains. The paint is pretty durable, but you will want to tickle the edge of how hard you can rub
and not lose fine details.
Very nice work!
I’m afraid I lack the proper equipment and/or acquaintances for this kind of work. 
38 degrees Science.
Me Too!
@jkopel, it’s good to see you again. Been gone a long time, you were the first to get a Glowforge. 
Or… clean the metal well (good call there I use bon ami), put on blue tape, burnish it with a spoon, etch, peal off tape.
I think if you sprayed any kind of paint on top of the tape you could etch deeply without problems. One other thing I liked is that if you fold over the tape and seal it on all sides you don’t have to worry about the corners breaking through a paint layer.
My choice for the black Satin paint is that it cures really well and holds up to the abrasion from the synthetic steel wool well. The gloss version of the same paint did not seem to fully harden even after 24 hours, nor did it engrave very well. There was a sticky residue left behind after 2 passes.
Great discovery!
Really nice fabrication! The tape wouldn’t have occurred to me as resist. A lot cleaner than asphaltum.
I actually have some (ancient) asphaltum “soft ground” for etching. I did not even try it since I was afraid it would make a complete mess out of the laser.
I saw the same Anarchist that you did!!
