Re: spots and dots and UVBL solarplates
I really have never had a problem with this until I got a roll of the new 'improved' Pictorico Ultra OHP. I was getting this strange lighter dots on some of my palladium prints that were noticeable in the smoother toned areas. Anyway, as I mentioned a few days ago, I put on the UV glasses and observed the film as the vacuum frame sucked the backside of the film into the glass. And sure enough, the dots coincided with these little mini-Newton rings and little bubblets. So I took the advice of one the very helpful solarplate/KM73 printers and sprayed the backside (non-inked) side of the negative with one very light and even coat of Krylon #1303 clear acrylic. I taped the negative to a piece of cardboard, stood it up nearly vertical in my darkroom sink and got my chi nice and centered and my karma in order and sprayed the backside of the negative from a distance of 12-18 inches. It dried to a faintly granular appearance that worried me. But the UV densitometer showed no measurable difference in UV transmission density, and it printed beautifully with no problems. I observed the negative-to-glass contact again as it exposed, and nary a ring, bubblet or anything else. So this is the way I will solve the problem until I get through this cursed roll of film and can move on to something that takes a little less care and feeding. Clay > Good morning all, > I've been thinking about this dotty discussion...it's interesting that I > have never noticed a spot discussion on the list until after MONTHS of > discussing it re: solarplate, and then FINALLY it comes out that other > processes have this issue. Several of you, e.g. Sandy King, have it. I > wish that it was mentioned way back when, Sandy and others, that you had > this issue with other processes, too, because that would have helped > narrow > down the culprit much more quickly (and saved me big bucks). > > I have never seen this with gum so assumed it was a characteristic of > photopolymer only until others came forward. I also assumed that it was a > factor of UVBL in combination with photopolymer and then come to find out > the spotty issue continues to plague those with expensive point source > lights. So, if the spots are truly just Newton Rings and a factor of the > top > side of the transparency in contact with the glass also, that seems much > more manageable in the long run--see what the list can do if we take the > time to share? Maybe we should spray the top side of Pictorico with > Krylon? > > One last thing about spots--if these plates are used for computer chips > (am > I not mistaken?) then the computer industry has GOT to have solved this > problem... > > But my real question is this: why has UVBL been considered a bad source > for > photopolymer, that point source is better if, in fact, the spot issue > still > is a factor with point source? I cannot see anything wanting in my UVBL > images, except the spot issue. I can see that when the aquatint exposure > is > too great, the image becomes mushy (Susan, like your step wedge image at > the > bottom of your blog), but if the aquatint screen and the positive are in a > 2:1 to let's say 1:1 the images are sharp and tonal. Until I get that ol' > Amergraph I won't be able to do a side by side to see the dif, but what is > it I might expect when switching to point source that will "wow" me? > Chris > > >
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