photomc said:Tried to do some Ziatypes this weekend and kept running into the same problem. Either the print came out with only some detail, or it was 'muddy' for lack of a better term. Posted an example of each one, the one I suspect is because the exposure was not no enough (using the big UV source in the sky) and that could be due to the fact that the clouds only show up when you need a UV source, otherwise they are totally absent..one of those weekends. The other though could be over exposed, but it does not have the sharp detail that the other has. The chemicals are about a year old or so, could this be the problem. Process was step by step from B&S, paper is Cranes, Any thoughts (besides buy/build a UV light source)?
Thanks,
donbga said:Mike,
2) Your over coated borders look as though they have good DMAX for your exposure time so I'm guessing that your negative may be somewhat dense but with low contrast (not counting the areas where the light is coming through the windows). To solve this you can add some ammonium dichromate to the emulsion mix. I have several bottles of varying strengths running from 20% to .1%. Don't use NA2 platinum as a contrast agent with Ziatypes, it doesn't work. Ammonium dichromate does and does very effectively. With the samples you provided use a longer exposure time. With palladium printing print for the shadows and adjust contrast for the highlights.
Don Bryant
nze said:Hello Mike
The use of dichromate play on contrast but also on printing time. It could expand the printing time. if you use a 20% drop you will need about 2-3 time the printing time without dichromate.
but which paper are you caoting this also play on the contrast and inal aspect of the print.
regards
nze said:Hello Mike
The use of dichromate play on contrast but also on printing time. It could expand the printing time. if you use a 20% drop you will need about 2-3 time the printing time without dichromate.
but which paper are you caoting this also play on the contrast and inal aspect of the print.
regards
photomc said:Question if this was due to uv light or once the print has developed to a point is it not possible to obtain good DMAX? Since the sun was dancing between the clouds.
So now the question, How do you kow the exposure is correct by looking at the negative/paper combo in the contact printer?
photomc said:Sandy, either I'm not understanding or ask the question incorrectly - what I was wondering is, how can you tell if the print has enough exposure WHILE you are exposing it.
donbga said:Zias depend on a a paper humidity of at least 50%. Use a sheet of Mylar underneath the paper to act as a damn to prevent loss of humidity during exposure.
An art supply should have mylar such as Pearl Art Supply.matt miller said:I'm gathering all the supplies to try my hand at Zias. Where can I get mylar sheets?
Thanks,
Matt
Robert Hall said:I bought a roll of mylar from light impressions.
Also, how is the humidity with all this? I keep mine quite high and humidify the paper also. (Unless I missed that part of the discussion)
colrehogan said:I've made prints in anywhere from 34% to 80% humidity (I can't dehumidify the entire house) and I always use a sheet of mylar between the negative and the paper. Is there a way to tell if the paper has had too much humidity?
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