An old joke, from my college days:

“Do you know how you tell the difference between a Chem student and a Physics student?”
“The Chem student washes his hands *BEFORE* he goes to the bathroom”.

There’s some truth in that statement, especially with regards to corrosive chemicals…

Tonight I decided to give the toner transfer photomachining process another go. The toner transfer material is from PulsarFX and purchased from DigiKey Corp along with the rest of my electronics components for the bullet flight sensor and … some other projects.

First, I did up the “photo mask” in Adobe Illustrator. Since the toner side is face-down on the etch surface, I do a “transform – flip” operation to mirror the text:

Top to bottom are: plain paper proof of the printout, plain paper proof of the inverted mask, and the actual mask itself, on the toner transfer paper. At a buck something per sheet, it’s advisable to do a plain paper proof every step along the way

The toner transfer paper works by heat and pressure. They sell a unit for doing this, but I am not about to spend a few hundred bucks on a special laminator. So I liberated the clothes iron and set it to linens, and tried my hand at ironing on the transfer:

Well, bummer. I had cleaned the brass piece with my Festool random orbital sander with 220 grit sand paper. Turns out a brillo pad works better.

If at first you don’t succeed, try, try again, and try harder:

My Dad would call this “paying tuition”.

After playing around with different methods of applying pressure, I finally got something good:

And a piece promptly flake off as I start blotting the workpiece dry. (the paper is dextrin coated, and releases after sitting in water a little bit, kinda like a water-slide decal).

After about 45 minutes in the ferric chloride (yeech!) etch tank, this is what I managed. Not acceptable, but at least I have an idea that the system works. Kinda. The etching is about 0.2mm deep. The design intent had been to sand to the black (raised) border, then fill the inside etched area with an ink, leaving the brass text raised against a black background. The piece would then be matted into a framed artwork along with the panorama being presented.

(For now, I’m just going to stick to my wax seal and signature, thank you very much.)

(This is “R&D”. Failures are not unexpected; what’s important is documenting how things failed, and learning from it.)