Kallitype: Exposures too short
Thanks everyone for helping with all my kallitype projects. So far so good. I'm using Crane's paper 90# right now. I did a pretty good print the other day but shazam!, the image dried down a lot. I think at least 1/2 stop - 3/4 too dark. Live and learn from mistakes. No biggy.
My initial exposure time is 1 1/2 minutes. Either my neg is not dense enough (very probable) or my UV light bank is too much (8x18" UV) or too close to the neg. Right now, I think it is about 3-4" to the 8x10 neg.
I'm thinking I can either:
1. Decrease my exposure time to something like 45 seconds.
2. Lift up my UV box so I get about double the height (about 6-8" from the neg) and keep the same 1 1/2 minutes.
Does this sound right?
Post question. How long can I keep sensitized paper around after drying? I was thinking of putting inside a box. Will heat fog the paper?
it sounds like the neg may be thin you can always add dichromate to the developer to increase contrast
are you using in-camera negatives or digital negatives? This is a relevant question as if you have digital negatives you can quite easily tailor your negatives to have one exposure time that will work for every negative. It is more difficult when using in-camera negatives. I am using BTZS for exposing/developing in-camera negatives and I always have to work a little to give the prints correct exposure. BTZS is precise but I still have some variability.
I would suggest you do some quick test to establish your standard printing time. Make a print of standard Stouffer step wedge according to BTZS procedure. This will tell you if need more dense negatives or you need to decrease exposure. It will benefit in future.
Using dichromate to increase contrast can sometimes give you grainy prints. This is not what I would do.
Sounds like thin negatives. Are you getting much contrast?
I use lith film negatives and my exposure time is around 8-10 minutes. This is fairly standard from what I've read of others. I also have negative around 3-4 inches from UV tubes. I don't think raising lights will make a big difference.
I'm guessing that your negs need more development or higher density.
Something is very wrong if exposures are in the 1.5 minute range with a bank of UV tubes ate 3-4 inches. One expects exposures of at least 6-8 minutes with kallitype and this type of light source. Even with a 1200 watt continuos wave xenon plateburner my exposure times for kallitype are in the 3-4 minute range.
Originally Posted by davido
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Thanks for everyone's help and suggestions on what to look for. The 8x10 negs do look just right for regular printing. I made quick contact sheets with RC paper and they look fine.
Originally Posted by sanking
I will test a couple of sheets this weekend with very dense negs via more processing time.
I found a great way to test for proper density and contrast is to make an RC contact print using a Grade 0 filter. A grade 0 filter will give you approximately the same contrast as the VDB/Kallitype process. Without a grade 0 filter, an RC contact print should look quite contrasty.