I just etched a few boards using muriatic and h2o2.
irmcdermott, you are exactly right. The Sharpie was hit or miss. I've e-ordered a couple of Staedtler Lumocolor markers since I've read they are the ticket for this application.
I tried using a silver metallic Sharpie in a couple of spots and it didn't work so well. Maybe a different color would work better? I dunno.
My latest problem is when I used acetone to wipe the toner from my board, it mostly came off clean- but there are some spots where it smeared & stained my background (the material under the copper clad I'm using is nearly pure white, btw). Does anyone know how to avoid smearing toner?
thanks again!