Uh-oh, very strange.
- Try no pre-wet. Extend the coating solution with distilled water if the paper has absorption problem. Or try to add some tween (1-2 drop of 5% Tween per ml of coating solution)
- Dry the paper thoroughly. At least an hour in standard room conditions. (What is the RH of your working space? 50-70% is ideal...)
What developer were you using? Try to switch developer to see if that is the problem?
Loris,thanks much for the suggestions. May I ask what "extend the coating solution with distilled water" means? And how to judge if the paper has absorption problem? Sorry for the ignorant questions. :P
The RH of my working space is about 65%. I'm using sodium citrate as developer. I'll switch it to see what will happen.
Extending means adding a little distilled water to make the solution easier to be absorbed into the paper. If the surface of the paper doesn't get perfectly matte (but remains shiny) within 4-5 minutes, you may have absorption problems. And the gelatin coating of COT320 particularly doesn't help there. Also, dry the paper for at least 1 hour. (Do you experience excessive print out? You should see tone ONLY in the darkest shadows.) Drying: First 20 minutes flat, 40 minutes hanged. But really I'm out of suggestions. Maybe adding some contrast agent to the coating solution or developer. But I don't see how could that help in the shadows (where your actual problem is), the contrast agents are much much more effective in the highlights, much less effective in the shadows...
Loris, sorry for the late report. I just came back to the experiment lately.
I've switched developer and paper and had almost the same result. So something must be wrong with my workflow as you suggested. I use a synthetic brush and before coating, I used to dip the brush into a beaker with some distilled water in it. Then I would drain the brush by the edge of the beaker for several times until it seemed properly moistured. I decided to make some change then.So now after I dip the brush wet I use some kitchen paper to absorb the extra moisture in it. And surprisingly it did make big difference. I should have mentioned this should I know it's so critical. Now I can see step #2 and #3 get merged when dried on the step tablet not covered by any transparency.The exposure time was ten minutes. But there's one thing I don't understand. Almost all the numbers on the tablet seem to become fatter. Is this called "bleeding" you mentioned before? Is that normal?
And later on for comparison I exposed both the 21 step tablet and the 31 step tablet(newly bought) for 15 minutes.Is it strange that on the part not covered by any transparency,no clear whites can be seen on the 31 step tablet while I still have three steps of clear whites(19-21) on the 21 step tablet?
The exposure distance above is about 3.6 inches.And I've also exposed the 21 step tablet at a height of 2.4 inches for 15 minutes too. Except that the numbers are getting fatter more obviously(not covered by transparency), no obvious density change can be observed and the steps under the transparency still seem to be far from full black.
Is that normal? Should I try for a even longer exposure time? Should I consider that the light source (HITACHI F30T9/BL) is not appropriete for the transparency film? (Is there any website for checking the spectrum of light sources?) Or is there still anything wrong with my workflow?
Thanks a lot!!
Numbers becoming fat in step tablets usually indicates gross overexposure - IF the contact between negative and paper is good. (Check contact first!) It's sometimes called bleeding, but not in the sense I used the word before; this one is light bleeding or better light creeping (in high contrast areas). Bleeding is where you loose image substance during processing, caused by the fact that the emulsion wasn't sufficiently absorbed into the paper. You observe light creeping right after exposure and before processing but you see bleeding while processing.
Have you tried to wait at least 1h after coating / before exposure? (This is maybe the third time I ask it; it's important...) The effect of the water content in the brush ect. will zero itself given the fact that you have adequate and stable lab conditions. (For instance: 20-22C, ~60% RH. Stability is important in order to make the test results correlate successfully.)
The images are too small for me to draw any conclusions; I don't see any paper white and I can't determine where tonal progression ends. (Is it a warm base paper?)
I think you're getting closer, an important remark: With correct exposure, the small writings in Mark Nelson's 31-step tablet should read clearly (under the OHP), without getting fat to the point being unreadable! If the surrounding black area gets fat to the point you can't read the small typeface, then you're definitely overexposing.
P.S. A last remark; don't try to match the blacks under the OHP with blacks w/o any transparency material above them; there's always some (small) difference with print-out iron / iron-silver processes. Just try to get merging steps under the OHP and work out the final exposure time by substracting 1/3 stop for the step tablet and substracting more to have max. black on step 1.
Last edited by Loris Medici; 02-23-2014 at 10:49 AM. Click to view previous post history.
Reason: Added P.S.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Loris,I'd thought too I was getting closer and inspired a lot by your comments but still no good news.
Yes I did have left the coated paper in darkness for at least one hour.And sorry for the images.I took the pics in tungsten lighting but forgot to adjust white balance in PS before I moved them into a new document with white background.The paper is COT-320.
I've tried exposure time of 20 mins,30 mins and 40 mins.In the 30-min strip, I could still see the tonal seperation between step 2 and the above,while in the 40-min strip it was overexposed obviously. That made me feel quite depressed and wonder if I could ever work it out.
Hi Sudek, when I have time (within 1-2 days) I'll download your latest step tablets and fiddle in PS to see better what's going on there... Will return then.
Attachment 83528Attachment 83529Attachment 83530
Thanks so much,Loris.I decided to retake the pics in daylight when I saw your reply.And when I examine them carefully I found that it's really not so clear white compared to the paper white.Not sure if it was due to clearing problem or overexposure.I used two baths of clearing agent(5 mins in Citrid acid and 5 mins in EDTA) which I'd thought might be enough for test strips. So I think I should test again.Frankly speaking it's your warmhearted help that encouraged me much to continue.
I exposed both the 21 step tablets for 35 mins,half covered by OHP and ultra OHP respectively.And for the 31 step tablet half covered by ultra OHP,I exposed for 40 mins.Then I used three baths of clearing agent(5 mins in Citrid acid and two baths of EDTA for 5 mins respectively).But I should have masked some part to check if it's fully cleared,as there still seemed no clear whites to me when I examined the strips later.
And unexpectedly I saw step #2,#3 merged on the 21 step tablet covered by OHP.Though I couldn't see very clearly whether #1,#2 got merged on the 21 step tablet covered by ultra OHP,it's quite obvious that #2,#3,#4 were merged on the 31 step tablet covered by ultra OHP (but the typeface could be hardly discernable).
Could I jump to the conclusion that the standard exposure time is 1/3 stop less than 40 minutes?(that's 32 minutes,right?) Or should I try to expose the 31 step tablet for 35 minutes for a better judgement?
Thanks a lot!
P.S. I attached the files in smaller size for a more quick download if needed.
Hi sudek, I see gross overexposure (up to the point you're experiencing bronzing / solarization) with all step tablets.
Do you have a scanner? If you have a scanner just scan a step tablet print made by fully covering it with OHP material, then use the Average tool to average each step into a single tone, then desaturate and then use the levels or treshold tools to assess better where merging takes exactly. You'll be surprised that you are getting the max black at pretty high steps (5-6 as far as I can see) and that the lower number steps are actually lighter! Once you determine the densest step, the calculation is easy.
For istance; If the darkest step (with the 31-step tablet) is step 5 under OHP, you have to decrease exposure until the darkest step becomes step 1. That means you should give 5 - 1 = 4 steps = 4 x 1/3 stop per step = 1 1/3 stop less exposure. But the step tablet itself also has a base+fog density of around 1/3 stop. Therefore you actually have to decrease exposure by 1 1/3 + 1/3 = 1 2/3 stop. For a 40 minutes exposure that means 40 / (2 ^ (1 2/3)) ~= 12,6 minutes ~= 12:30 - 12:40 minutes in time notation. (Seconds don't matter much at 12 minutes timespan...)
Hope this helps. Definitely scan the test print to be able to make absolute comparisons...
P.S. Look not for merging steps, look for the darkest step.
Last edited by Loris Medici; 03-03-2014 at 09:27 AM. Click to view previous post history.
Reason: Added a final clarification