Press-N-Peel and my crapy printer

[alparent]

I etched my first enclosure this weekend.....look not to bad.

I didn't use P-N-P (cause I didn't have any!)

One thing that happened is that my toner covering was not perfect. It looked good to my eye but after etching and cleaning everything. THere was like a bazillion little pits all over the enclosure.

My question......would using P-N-P take care of those tiny holes since it says that the blue is also a etch resistance?

Also how long, and deep dose the etch needs to be?         I left it there 30 min.

[Mark Hammer]

One of the difficulties with trying to iron on toner patterns to aluminum chassis is that aluminum does a pretty decent job of being a heat sink!!   That means that you tend not to get efficient transfer of the entire pattern to the chassis surface.  I suppose one could say that this is where the Sharpie pen comes in handy to fill in the gaps, but I would be the first to recognize that this is not always feasible OR an efficient use of a person's time.

It is probably true that PnP not only has more precision (by virtue of particle size) than photo paper, but also that it has more efficient heat transfer through the acetate sheet than photo paper has through heavy paper stock.  Still, that stupid aluminum will suck the heat away from the point of contact almost as fast as you can supply it.

Certainly one thing to always keep in mind is that surface preparation is every bit as important for etching a chassis as it is for etching a copper surface.  And, insomuch as most copper board comes in a state that is much closer to the ideal than your average aluminum chassis, that means there is a LOT of prep work to do on a typical Hammond chassis before etching it works out well.

[KazooMan]

I tried my first attempts at etching recently and I used press and peel blue.  I was careful to turn up the darkness on the printer to get the maximum amount of toner.  I carefully cleaned the aluminum surface (a sheet of aluminum I purchased, not a box).  I spent a lot of time with the iron trying to make certain that the transfer was complete.  When I peeled off the PNP and looked at the sheet there were essentially no places where it looked like the toner had stuck on the plastic. 

So...... off to etching.  Carefully using a cotton swab to dab the etchant on the aluminum.  It all looked great........ until I finally washed it off.  I had the same zillion pock marks around the design that you have. 

So, attempt number two:  I bought several markers (Sharpie and a few other brands at a local art store) and tried them on the back of my first disaster to see which ones gave the heaviest coating.  I then tried some etchant to see which one stood up the best.  On the the second piece of aluminum.  Same careful prep, and ironing.  All looks good.  Then I used the marker to carefully add more "resist" to the transferred design.  This time I carefully dabbed on some etchant and after a while I rinsed it off.  I could see some places where the resist was failing or about to do so and I touched them up with the marker.  I did this for several rounds and then a final rinse and I washed the marker and toner off with some acetone.

This turned out much better, but there was still a few pits where the resist had failed.  I then used a bottle of auto touch up paint to fill in the appropriate parts of the design and used 1500 grit (auto supply store) to sand down any paint that had flowed over the boundaries.  Finally a spray of clear coat.  Here is the result.  You can see the pits around the lettering, but it is not too bad, especially when the design is highlighted with the paint.  I  still have a lot to learn about doing this, but I don't know how else I could have made really durable labels for the pedal. 

There is a tutorial on the site about making multicolored etchings.  I believe he uses nail polish to repair bad spots on his toner trasnfer prior to etching.