U of S | Mailing List Archive | alt-photo-process-l | Re: solarplate wedgies

Re: solarplate wedgies

Christina Z. Anderson wrote:
This weekend I had to print an edition on solarplate and I had chosen chine colle as part of this print's process. What a stupid mistake. My KM73 plates that were exposed for 49sec aquatint/41 seconds positive and post hardened extensively (I noticed that when the plate is hardened it goes from pale celery to pale aquamarine) the chine colle with its moisture dissolved the surface of the plate. I did this once and thought, well maybe the plate was just breaking down and Jon was right--you can't get a lot of pulls on one plate. So I went home, made two more plates, and brought them back. Same thing happened again. Needless to say, you can imagine how frustrated I was wrecking three plates!!! Even tho the back of the chine colle was dry, of course when run thru the press it squeezed through to the surface of the plate. I finally had to chine colle without moisture, in essence printing on top of the tissue paper in register with the back paper, and will post glue it. Any of you chine colle with KM73?

I did make about 35 prints this weekend, btw, and the plate held up fine, so if there is no moisture it is sturdy.
Hi Chris,

Sorry to hear about your frustrations. I've done chin colle, though I'm not very proficient at making good looking art with it, it is doable with the KM73s, as with any polymer plate. What's your technique like for doing chin colle? Typically I take the paper elements, spray them lightly with water, dust with non-fortified flour or wheat paste, then lay gently on a fully inked plate, glue side up before running through the press onto damp paper. If you don't want the ink on top of your chin colle element, cover it with frisket or a piece of mylar. There are many approaches. You of course never want water or overly saturated paper to come in direct contact with a non-inked plate once it's been processed since it will destroy mar the plate.

I also found out one more thing (where are you Susan, Jon, Keith? Spring break??). This leads back to what I said about wedgies and my surmise that you can use a number of different exposure times but the ratio is the most important. The plate that was exposed UVBL 49/41 which looked tonally really nice was much less sturdy than the plate I finally printed from which also looked tonally very nice--2min/45 seconds. In fact, that plate produced a sharper, darker print. I am thinking this and correct me if I am wrong:

The plate is .73mm thick--the longer the exposure, the thicker the "goo" on top stays, up to a certain point where the whole plate is overexposed and will print complete white. I think it is like gum printing! With gum, you can choose a shorter or a longer exposure time and the layer of gum arabic/pigment is thicker or thinner (vertically) but also a deeper color happens the thicker the layer because, naturally, there is more pigment suspended in a thicker layer vertically.

So, I am going to stick with my original theory that it is not the exposure time that is crucial but the ratio of aquatint to positive that is the most important. I can test this by doing a, let's say, quadrupling my 49/41 ratio for instance, and probably see if this assertion is correct. AND I wonder if that plate, thicker and harder, will be able to withstand chine colle better.
Not sure what to say about ratios, other than I'll be interested to hear about the results of your test. At one point I tried converting my 5K watt times for an exposure at 1K and found the 5K had more pop to it for some reason. The 1K seemed to have less sharpness and richness. I'm sure I could have continued to dink around with exposures at 1K and gotten decent results, but I have stuck with 5K. My math could have been off too, certainly. :-P

My sense is, you want to try and get exposure times of screen/image to get the blackest blacks you can get with a given set of screen/image exposures, then tweak the adjustment curve to bring out details in the shadows and create clear separation of tones, using a step wedge as the guide.

One other thing--I switched to PhotoWarehouse OHP and all inks on the 2400. I can manage to get one plate made from one neg before the neg breaks down (the ink comes off easily) and it will take all inks but not colored only--that smears. I had to, in "Ink Config" switch the pass time to 50 (5 seconds between each printer head pass) to make sure nothing smears also. the PWOHP is much thinner and more flexible than Pictorico. I did this because of the measle issue and several authors recommending that you switch substrates if measles occur. I powdered both the back and front of the OHP. I got one or two spots per plate in the very darks only and they did not print.
BTW, did you ever try the sun vs. UVBL tubes to see the difference? I'd be interested to hear your impressions and to hear if that made any difference in pursuit of eliminating the measles. Maybe changing substrates is the best solution for you Chris, but I've not found a better looking substrate than Pictorico OHP. If you find something that is comparable, changing media is certainly cheaper than buying an Olec unit and vacuum frame or running around in the sunshine with photosensitive media and trying to be precise about it though! ;-)

In my world lately: After much tribulation, I've finally broken down and bought an Epson Stylus 7800. The pallet arrives on Wednesday! Still working on new sources for the finer 1800 dpi stochastic screens I've been using successfully for about the last year and have two strong leads cooking. Also talked with the owner of Box Car Press and confirmed the availability on A1 plates (40x30") for the KM73s. I'd probably cut them in half though since the 7800 can "only" do 24" wide though. </gloat>

Let's all post some recent polymer gravures soon, eh? I've been too busy doing other people's plates of late to be able to do much of my own work, but that will change soon.

Have a great week everyone!