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View Full Version : The use of UV Activated Emulsion as a Resist for Etching.



Dennis
01-07-2013, 09:21 AM
I mentioned this subject in May, but it has been a term-long class project, so I have only just been able to write it up. Some of my fellow students had very impressive results, particularly with fancy fonts, handwritten mottoes and signatures. Photo-resists allow the black parts to be etched away, creating a recess for colouring with a patina, or even, as once suggested by msgeorge, filling them in with a sharpie.

Here a link to my detailed account in WordPress, which I hope will make it easier to read, and print if you wish: http://dennismlondon.wordpress.com/2013/06/30/etching-resist-2/

Dennis.

ps_bond
01-07-2013, 09:48 AM
Excellent stuff, Dennis. IIRC you've used Press'n'Peel as well - how do you feel this compares?
I have a UV exposure box somewhere from PCB days...

medusa
01-07-2013, 09:51 AM
I think it is safe to say you have my eternal gratitude!

Dennis
01-07-2013, 09:17 PM
Thank you both.

PnP is much cleaner to use, of course, but it does need a dark room , not just a dark corner. Also the protective film is tricky to remove ( I have recently seen that you do it with sticky tape), and fine lines tend to loosen in the etchant.

The consensus in the class is that the emulsion gives a superior adhesion, but we are also now using iron salts, which are less aggressive than nitric acid.

Both Sherri Haab and Nancy Hamilton have videos on line showing the use of film, activated by home made UV light boxes. Their darkroom lights are yellow bulbs, used in the US for after-dark garden parties, because they don't attract flying insects.

Hardly a romantic ambiance, unless they use the correct make up to compensate. Dennis.

mizgeorge
03-07-2013, 10:31 PM
access to a dark room is not a problem for me, the other half has one three times the size of my little workshop.

I never ever have managed to use PnP. Stuff always seems to get mangled in the printer so I generally have been using photosensitive film which I expose on a sunny day. obviously this means I only do it three times per year, but...Better get moving quickly then - we're meant to have two weeks of good weather coming up from the end of the week ;)

urgh. It's doing that weird out of order posts thing again.

medusa
03-07-2013, 10:32 PM
access to a dark room is not a problem for me, the other half has one three times the size of my little workshop.

I never ever have managed to use PnP. Stuff always seems to get mangled in the printer so I generally have been using photosensitive film which I expose on a sunny day. obviously this means I only do it three times per year, but...

Dennis
04-07-2013, 05:05 AM
PnP is much cleaner to use, of course, but it does need a dark room

Obviously my brain (if any) had shut down when I wrote that, because I was referring to photo-sensitive film.

The problem with PnP is that thin printed lines are quite fragile, it needs a laser printer which uses toner, not an inkjet, and ironing it on is challenging to do well. It gives a positive image, which can be a plus in some cases, but not with writing.

Lastly when ironed on the resist forms a mirror image, so the original image might need to be reversed first. Interestingly those students who had been working with resists for years were pulled up sharply by these differences. Dennis.

medusa
04-07-2013, 08:57 PM
Obviously my brain (if any) had shut down when I wrote that, because I was referring to photo-sensitive film.

The problem with PnP is that thin printed lines are quite fragile, it needs a laser printer which uses toner, not an inkjet, and ironing it on is challenging to do well. It gives a positive image, which can be a plus in some cases, but not with writing.

Lastly when ironed on the resist forms a mirror image, so the original image might need to be reversed first. Interestingly those students who had been working with resists for years were pulled up sharply by these differences. Dennis.

I wasn't reading properly either or I would have been confused. Instead I think my brain just made the intuitive leap.

but I've never got on with PnP.

I've had no problem with fine lines, I use it for fingerprint etching and get good results. Once you get the hang of it, it's pretty easy to use but a paint on photo emulsion sounds more convenient. I have a huge role of film if anyone wants a go of it.