Monday, 14 January 2008
Trials with PHOTRAK a photo acrylic etch application
Doesn’t look like much but this and the five other images which you can see in the back room studio represent a whole week of trial and errors at getting this roll on, acrylic etch, process to work.
I had previously used this brand of photo etch at href="http://www.londonprintstudio.org.uk/">London Print Studio and although one would have days where the first attempt might not work the second one nearly always did and I transferred some very fine and detailed inkjet transparencies onto my copper plates quite successfully.
I first tried leaving it on the UV exposure unit for 18 seconds followed by 15 then 14 then 16 and the image was becoming apparent, in the developer tray of soda crystal mix (10 grams to 1 litre of water by the way is the standard mix for this) but the image would not stay on the plate after I carefully removed it and placed it in a tray of clean water to rinse it.
So after that first day I thought to myself I have got to speak with Paul Dewis or Lisa Chappell both print technicians/ coordinators at LPS.
Which I did, explaining my efforts in detail. When Lisa said that it was 45 seconds and not 18 seconds I was relieved thinking "Oh great well at least my next days efforts should prove more promising!!!.
However I carried out the tests of the six copper plates which I duly degreased with "Jif" cream cleaner of course, and still it wasn’t really happening. I couldn’t believe it!!.
When I spoke to Lisa again I asked her what wattage their UV box was and therein the problem lied. Our homemade UV box was a total of 250 watts (comprising 2 bulbs, each one being 125 watts, whereas their UV box was/is 1 kilowatt. So I thought multiply the 45 seconds by 4, as their box is four times stronger than ours and hey presto the development time is now established as three minutes.
So the image you see here is the first one that worked - it was a grainy transparency with liquid tuche on it.
Now that I have got over that hurdle I am wondering about the aspect of rinsing them satisfactorily as some parts of the copper plates which should be open for the ferric chloride to break through and etch appear to be not completely open. It's not that easy to judge. I wish now I had left them in the ferric chloride as they would take overnight to be etched if not 2 days.
I was reading in my most recent technical print making book "Intaglio" by Carol Robertson and Robert Adams that one gently wipes it with a soft brush or a sponge which is what I remember doing at LPS. Actually at LPS - we used a swab of cotton wool. You can’t get gentler than that!!