Determine the basic exposure for palladium printing

[sudek]

Loris, the UV light is HITACHI F30T9 fluorescent lamp.

May I ask what bleeding means? Sorry for the ignorance

Thanks a lot!

 

[cowanw]

Bleeding is where the blacks run (or leak or spread) into the whites.
Loris, I hesitate to reveal my lack of understanding of things, but do not these results indicate a lack of sufficient contrast. Sudek, at what contrast mixture are you doing these?

 

[Loris Medici]

Sudek, this is a 36" / 30W lamp with UVA output peaking at 350nm, right? 30W per 36" is a little on the weak side but perfectly useful. My 24" bulbs are 40W for instance, yours should be equivalent to 20W / 24". Not strong, but not weak too. I know people printing with 20W lamps and our exposure times are close to each other.

Apart staining whites, bleeding is loss of image forming substance from paper, therefore leads to weaker dmax.

Bill, I know no dop pd mixture that exceeds log 3.0 exposure scale - if there isn't something really wrong with sudek's mixture, that is. That's why I asked about their FO, maybe it's stale.

sudek, measure FO enough for one print and try to mix 1 drop of OTC peroxide (3%) in it, swirl, wait a little then add the metal and print. See what happens? If things get better, it's stale FO. You should better choose to mix a fresh solution instead of fiddling with peroxide addition; it's hard to control that.

Regards,
Loris.

 

[Herzeleid]

Hi Loris,

Just squeezing some info on bulbs, I am using 24" 20W BL368 (a set of 10 with some diy reflector in the back). Well,my exposure times are quite close to Loris's, differences are mostly from the base densities of different materials.

Sudek's 40 minutes exposure really sounds strange to me. Yet again I have no experience with DOP pt/pd, but I would not expect such long exposure.

Regards
Serdar

 

[sudek]

Cowanw, I use a mixture with equal amount of FO and palladium solution.According to Dick Arentz's book, the appropriate exposure time/distance can be dertermined this way by having two to three black wedges reach maximum black and indistinguishable from each other. I did experiment with decreased distances last night,1.8 inches, for example, and exposed for half an hour.Then I saw bleeding and several numbers got blurred.But still I didn't see any step reaching maximum black. As I'm planning to make palladium prints with digital negatives, I'd like to control the contrast of the negative to match the paper, rather than controlling the contrast of the solution.But I don't know now how to get that basic exposure time. Pity that I don't have NA2 on hand otherwise I'm eager to see what happens if the contrast changes. And how come my contrast obtained with a "normal" mixture of sensitizers are so different from others?

Loris, thanks much for the kind suggestion. And if the coated paper can reach maximum black in several minutes, may it prove that the FO is not so stale?

 

[Loris Medici]

...
Loris, thanks much for the kind suggestion. And if the coated paper can reach maximum black in several minutes, may it prove that the FO is not so stale?

Hi sudek,

I'm totally puzzled here. There's something wrong with your workflow and/or materials - but couldn't pinpoint the problem so far. I'm out of suggestions really. I'd check the materials (different paper / different chemicals) to rule out that probability. Purely because it's simple to do that, if still having problems, I'd check my workflow.

Good luck & regards,
Loris.

 

[sudek]

Loris,

I did what you've instructed before, mixing 1 drop of OTC peroxide (3%) in it and you're right. It's stale FO. Now I got clear whites in the step from 18 to 21, the part under the cover of OHP is from 16 to 21. But other than that, the steps seem just a little bit darker and still lack of full black. The exposure time was 20 minutes and distance to the light was about 2.6 inches.

There's just one more question I'd like to ask. Is it possible to have full back using stale FO with peroxide added?

Thank you so much for the patience and all the kind and detailed suggestions

 

[mitch brown]

Sudek
here'a a thought for you , also being new to pt/pd I was having the same problem until a friend who is a long time printer showed me that I was over exposeing causing the blacks to have bronzing so they didn't look as dark a black.
mitch

 

[Loris Medici]

Hi sudek, I think you can use a stronger dilution of peroxide (15% or even 50% - but peroxide is kinda DANGEROUS at that dilutions, it may BURN your skin and stuff, therefore BEWARE! I'd go for the other SAFE way...) and add some more to fully convert iron(II) to iron(III) in your sensitizer solution w/o diluting it too much. I think adding just enough peroxide (not more than enough) will totally revive the solution w/o compromising it. BUT, I'd really prefer to purchase dry FO and mix a fresh iron solution. Mix small batches that you'll use up within a couple of months max...

mitch, sudek's problem isn't bronzing, it's the other way around.

Regards,
Loris.

 

[sudek]

Loris, thanks a lot!! It sounds difficult to find out the quantity of peroxide as "just enough" though. And I'm wondering also if this is a contrast control problem. I'm not sure now if I could have full black in the step tablet with a solution including only FO and palladium.

 

[Loris Medici]

Hi sudek, you can, I do, everybody else can do it too. JUST use fresh FO. (About peroxide addition: You can empirically test with small batches, increasing peroxide amnt. step by step until it doesn't do any more good - but if I were in your place, I'd really not bother because that would mean building my whole workflow based on flawed material, something I would highly refrain...)

P.S. I do pop pd w/o any contrast agents, exposure scale log 2.9 (29 steps with 31-step tablet, 19-20 steps with the 21-step tablet you are using...), dop pd should be considerably below this figure, because there isn't any significant print out that would necessitate a negative with higher density range.

Regards,
Loris.

P.S. I think dop pd w/o contrast agent should give you about 15-16 steps with the 21-step tablet...

 

[sudek]

Loris: It's so assuring to hear that. I'll get fresh FO and see what will happen. Thanks a lot!!

 

[Loris Medici]

Hi sudek,

If possible buy dry powder FO and mix the sensitizer solution yourself. Dry FO keeps very well (as long as the container is tightly capped and protected from UV), therefore you'll have the opportunity of mixing small batches that you'll use up within a couple of months - w/o getting stale.

Goof luck,
Loris.

 

[sudek]

Thanks much, Loris. I'll post the result later

 

[sudek]

I got the fresh FO finally and I exposed for ten minutes first with the same workflow. And when I saw the result, I exposed for twenty minutes later. Both of them were still lack of full black.

For the ten-minute test strip, I got clear whites in the steps from 20 to 21, the part under OHP is from 17 to 21. And the shadow steps are quite far away from full black.

For the twenty-minute test strip, the same result in clear whites when using stale FO: no clear whites in the steps and the part under OHP is from 19-21.
But it's great to find that it got slightly darker in the shadow steps compared with the strip using stale FO. Yet still no full black.

BTW, I could have full black in the paper without the step tablet/OHP.

Is it that the exposure scale of the paper not long enough to have the step tablet show full black? And which part of my work flow should I consider problemetic?

Thanks much in advance for any kind suggestions.

 

[Loris Medici]

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?

 

[sudek]

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.
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.

 

[Loris Medici]

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...

Good luck,
Loris.

 

[sudek]

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!!

.

 

[Loris Medici]

Hi sudek,

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.

Regards,
Loris.

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.

 

[sudek]

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.

 

[Loris Medici]

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.

Regards,
Loris.

 

[sudek]

View attachment 83528 View attachment 83529 View attachment 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.

 

[sudek]

The above attachment seem to be problematic.I'm trying to attach again.

 

[Loris Medici]

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...

Regards,
Loris.

P.S. Look not for merging steps, look for the darkest step.