Transfer using overhead transparency

Paper and acetone works pretty good, parchment paper works ok but neither lets you see through the paper to align an image to something that's already there. An overhead transparency is the answer but how to transfer the image?
Clear epoxy works but takes a while to set and if you get the quick setting kind then you only have a few minutes to get it spread and your image placed. Plus it's viscous which makes it hard to get a thin layer on the metal. Superglue doesn't work, neither does Loctite thread locker. What you need is something that doesn't set up until you tell it to, doesn't attack the toner on the back of the transparency and is thin enough to spread out evenly.
The answer is (and this is still a work in progress) UV cure adhesive. Loctite 363 (Amazon) and a UV LED fingernail gel machine (need one that works at 363 nm and 405 nm wavelengths) (Amazon) work well. A little more expensive option is UV cure nail gel (Amazon) but you can't get it to spread as evenly as the Loctite 363.
Spread the adhesive on the work, place the transparency face down on the adhesive and press out all of the air bubbles. Expose the adhesive to UV light for 3 minutes and peel off the transparency. The image is adhered to the adhesive which is adhered to the metal. When you peel the plastic backer off the image stays on the metal. The adhesive is a little rubbery but not too bad.
I'm still working on alternate adhesives and light sources but this solution will work until something else comes along.
Sorry for the long post.

Interesting. I have some Seiko watchmakers UV glue and will give this a try.

It works slick. The key is matching the wavelength of the light source to what the adhesive needs. Typical wavelengths are 365 nm and 405 nm. Nail polish gel is either "UV" (365) or "LED" (405). Cheap LED UV flaslights are unreliable. The nail gel dryer is more consistent because it has to be tuned right in order to work. It sets the Loctite 363 hard as a rock in 3 minutes. Nail gel sticks better and removes more of the image but is more rubbery and harder to follow the line as you cut.
Like I say it's still in R&D. BTW a good soaking with Goof-Off takes the stuff right off. Clear epoxy and MMA resin are very difficult to remove.

The Seiko glue is also rubbery. I have a nail dryer UV light which works perfectly with it.

sam said:

I have a nail dryer UV light which works perfectly with it.

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i'm afraid to ask why you already have one of those. you haven't been hanging out on Bourbon St. again?

After you finish engraving the pattern how do you get the UV stuff of the metal?

I use Goof-Off. Put some on a paper towel. put the towel on the piece and place a weight on it. let it sit for 10 min and the adhesive bubbles up. A few passes with a brass brush and it's clean. Epoxy and MMA don't come off. You have to scrape them off.

Sam the Loctite is not too bad. If the wife has some clear uv base coat nail gel try that. The one thing is to make sure you have a transparency on top of the adhesive. Oxygen will inhibit the top layer from setting and leave an oily film if left bare.
I have an idea on an applicator to spread out thicker gels into a thin layer. The manufacturer says 1 mil is acceptable so if we can get that thin the rubbery problem may go away. I'll let you know when I try it.

mitch said:

i'm afraid to ask why you already have one of those. you haven't been hanging out on Bourbon St. again?

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LOL! No, it's for watchmaking purposes only (crystal cement). It cures in sunshine but the UV light is 10x easier and faster.

mitch said:

i'm afraid to ask why you already have one of those. you haven't been hanging out on Bourbon St. again?

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this thread proves that i'm not the only nutcase on the forum!

I did a wire wound applicator rod to give a consistent coating thickness. Used a 4" piece of 1/8" drill rod and wound it tightly with 28 ga (0.010") wire keeping the wire tight and the coils side by side (like making a long spring). Drilled a 1/16 cross hole about 1/2" from each end to capture the wire. Glued the wire in the holes with UV glue.
The literature says 0.010 wire will give a 1 mil coating thickness. Put some Loctite 363 on a practice plate and spread it out with the rod. After everything is coated well wipe the rod off and pull it the length of the plate one last time to scrape off the excess. This leaves 1 mil coating. Place a transparency toner side down, push out the air bubbles and expose using nail gel dryer for 3 minutes. When I removed transparency film most of the toner stayed with the glue.
Tried cutting through the adhesive and voila, the gummy texture is gone. The adhesive stays with the chip and you are able to see where you are going even with fine lines.
If you don't want to make a coating rod from scratch they are available from www.gardco.com for about $60 for 12" rod. They explain the theory of the wire wound applicator rod well.
I have a different kind of curing lamp coming from Amazon. The nail gel dryer works well but it's not large enough to fit anything much bigger than a practice plate.

the possibilities are endless...

https://www.gardco.com/app.cfm