Cinder,
If you don't mind, could you give us a quick rundown of your etching setup and procedure? I didn't even know that kind of result was possible with an etch!
Sure, I'd gladly be of any help.
I'll try to just write a list of what I have and what I do, its not really that different from anything you've seen other people do.
1. Sand the enclosure top flat down to 400 grit. I use a sanding block and go from 120 or 180 up through 240 and then 400. Using too fine of a paper from the start is a waste of time.
2. Clean the sanded surface using isopropanol (rubbing alcohol) and some household paper.
3. Print the design on a glossy photo paper, I have some from a local hardware store that's 157g/m2 and is a real cheapo brand (20 small sheets for $5, each sheet takes only one print).
4. Cut out the design, I always have a few extra millimeters of black around the edge of the design which I tape over before etching.
5. Lay the design face down on the enclosure, put some folded household paper on top and then set your iron on top of that. I used the household paper for the first time with this enclosure and it works really well in distributing the weight/heat of the iron onto the whole surface - I really recommend this especially for a larger enclosure. Also a note here; I bought a cheap iron at a hardware store sale for $10, my only criteria was getting as much power as possible which was 2400W in this case, it makes a difference when applying heat to the enclosure comparing to 1400W irons or other. I always run the iron on maximum heat with no water in it for steaming.
6. Let the iron sit still, optionally give it a light press (not too much or the toner may smudge) for a minute or two. Then start to work the iron in circles, cross patterns, along edges etc on the enclosure, I removed the household paper for a while when doing this, then did it again with it just to get as much different coverage and pressure as possible. I ironed this large enclosure for 15 minutes.
7. When done ironing the photo paper should lay perfectly flat over the whole surface, if there are bubbles or raised spots, you are screwed and can either try applying the iron with the household paper for some time to try to set the paper, or you might as well admit failure. Been there done that.
8. If the photo paper looks good, toss it in a container of water immediately to get it to cool, works best if you are able to fill the inside of the box with water too, then it cools in a matter of seconds.
9. Start peeling the paper off, I start by using my fingers to roll of little rolls of the paper starting from the edges, the photo paper I have comes off in several layers.
10. When I have the bulk of the paper off I use a toothbrush with the bristles cut to half length to scrub the remaining paper off the enclosure, this works really well in getting all the little finicky bits out, like the small dots in the halftone pattern of the Destroyer pedal I just posted. It also doesn't really risk lifting the toner since the bristles scrub quite mildly.
11. Inspect for missing bits of toner or just weak coverage, if there is severe toner lift you just have to bite the bullet and start over - unless you can save it by point 12.
12. Use silicone to repair any missing or damaged parts of the toner, I have this small tube of bathroom silicone I use. It has pros and cons - Pro: It most definitely will not be eaten through by caustic soda. Con: You need to apply it and let it cure, then cut it to shape with a scalpel or similar and scrape the excess off the aluminium. This can be tricky depending on how complex the shape is that is messed up, so keep that in mind before starting to do touch-ups, it might be less work to just do a new transfer. Silicone is the only material I've found that seems absolutely resistant to caustic soda, regardless of the heat from the reaction. It can be a bit tricky to apply since it's like a thick paste.
13. When done with touch-ups use packing tape to tape the edges of the design, I put the packing tape over the black extra toner on the outside edges that I mentioned earlier. Make sure the tape seals nicely to the surface, i.e. press it down with your fingers. In the corners you may or may not want to put some silicone in order to prevent seeping where tape goes over another layer of tape.
14. Last check that you covered all the bits you need including touchups, tape and the toner transfer looks good.
15. Mix caustic soda. I mixed 25g of powder to 100ml of water for this enclosure, it's strong enough but not excessive, the solution doesn't need to be hot when applying it, I'd rather have it warm and let the reaction be slower, I don't trust the excessive heat to be kind to the tape, touchups or the toner for that matter.
16. Apply the solution to the enclosure, I use a synthetic brush for this. The etching went on for 15 minutes for this enclosure, then I checked it by running the enclosure under a tap and using the same cut-down toothbrush to scrub the soda and residue off, the etch was still a bit shallow so I set it back in my etching box (plastic box of any kind) and applied the caustic soda again with the brush and let it sit for another 15 minutes. After this the etch was good.
17. Rinse the enclosure under a running tap and use the toothbrush to scrub all the soda and residue off, the design should be clear to the touch now, mine was probably 0.5mm deep or maybe slightly more.
18. This is a good time to remove the packing tape and cleaning all the glue off with acetone, then tape the enclosure sides off with paint masking tape (tape made of paper, not plastic - doesn't leave glue residue the same as packing tape). Make sure to get all the silicone off at this point too, or it might mess up the paint job with greasy looking spots.
19. Spray paint the top of the enclosure, preferrably two layers, I do a bit thicker layers than you normally would because it seems to fill out the little irregularities in the etched metal. I use regular craft spray paint, nothing special about it.
20. Once the paint has cured, after about 2 hours or so, remove the tape, grap a sanding block and a 1200grit paper, sand the paint layer down slowly to see the design emerge without going too fast and sanding down any detail.
21. Any excess/stray paint can be removed with a q-tip and acetone, the etched enclosure is ready for drilling and whatever else you need to do to finish it.
Well.. that was a lot of steps in the end but I did kind of go into detail, I hope it gives some insight into what I do and whatever you might pick up for your own process.
Just don't get the impression that I do this without any hiccups myself, this enclosure took me several tries to get a good transfer, patience is key, at least until I can figure out something foolproof.
