Issues with VDB

[ndavidson2]

So last June I purchased a Alt-Process starter kit from B&S, which included all the materials necessary to makes Cyanotypes and VDBs. I've made a few successful Cyanotypes during the summer and fall, and over the past few days, have attempted to make untoned VDBs, with incredibly poor results. It seems that no matter how long I expose the VDB, it's completely overexposed.

I've attached a screenshot, where I exposed 4 different 4x5's of varying contrast, and exposed each one at different intervals. I even exposed for the shortest referenced time possible (2 minutes), and still came out grossly overexposed. This scan was taken several hours after drying, and most likely would only get darker with any more dry-down.

This doesn't seem "normal" to me. I figure I can expose my next print for 30 seconds (can't attempt for another few days), but that's well below any amount of time I've seen online (I also have Christopher James' book..).

Is it possible that the sensitizer is bad? Again, I only received it in June, which would make it about 8 months old. I store it in the bathroom at room temp, where there is no UV light coming. The only thing I can think of is that when I first got the package, I opened it up in the living room, next to windows where there would have been a decent amount of UV light coming in. I had probably left it there for a few hours (maybe it was a day?) before I moved it into my bathroom/darkroom.

For reference, this was exposed via the Sun, clear Winter afternoon skies in Ohio.

 

[pschwart]

What is the contrast index of your negative? You need sufficient density; log 1.8 - log 2.0 should do. On my monitor, it looks like your 8 min exposure is still not achieving maximum black, which suggest your negatives are way too thin.

 

[TheToadMen]

I would too first look at the negative too. Is there enough density? What kind of negative is it? (analogue film, inkjet print, ...).

If you have a normal 35 mm B&W negative strip lying around, you could also make a small test print to see if it gives reasonable contrast in the print with normal exposure times. I've never been in Ohio but I guess the sun isn't that strong during Winter? So I'd expect exposure times in minutes, not seconds?

If that doesn't give you any answers, then look at the chemicals.
You could also coat a small piece of paper and put some items on it that will block all UV light 100% (a scissor, a comb, a pen, a film canister, ...) and then expose this with UV light. If the covered areas turn out black instead of white (before and after processing), then you'll know the negative isn't the problem. So then look at the chemicals and your working process. (Are you're using too much sensitizer in your coating? Is the sensitizer off? Is there an other (unwanted) UV source during coating at work? Maybe a wrong paper and/or coating combination, ....)

 

[ndavidson2]

What is the contrast index of your negative? You need sufficient density; log 1.8 - log 2.0 should do. On my monitor, it looks like your 8 min exposure is still not achieving maximum black, which suggest your negatives are way too thin.

I do not own a densitometer, but my negatives are not what I would consider thin. The one that I exposed for 6 minutes made an acceptable cyanotype. I would venture to say that the negatives are somewhere between normal and "slightly dense".

I would too first look at the negative too. Is there enough density? What kind of negative is it? (analogue film, inkjet print, ...).

If you have a normal 35 mm B&W negative strip lying around, you could also make a small test print to see if it gives reasonable contrast in the print with normal exposure times. I've never been in Ohio but I guess the sun isn't that strong during Winter? So I'd expect exposure times in minutes, not seconds?

If that doesn't give you any answers, then look at the chemicals.
You could also coat a small piece of paper and put some items on it that will block all UV light 100% (a scissor, a comb, a pen, a film canister, ...) and then expose this with UV light. If the covered areas turn out black instead of white (before and after processing), then you'll know the negative isn't the problem. So then look at the chemicals and your working process. (Are you're using too much sensitizer in your coating? Is the sensitizer off? Is there an other (unwanted) UV source during coating at work? Maybe a wrong paper and/or coating combination, ....)

These are 4x5 analog film negatives (FP4 and HP5). I also used 8x10 xray film in earlier testing (which was very dense), and they came out the same.

I use the recommended amount of drops by B&S (10-12 for 4x5, 40 for 8x10) to coat my paper. I'm using the paper provided in the kit, which I believe is Stonehenge 110lb. I coat the paper in my darkroom/bathroom - just under normal incandescent lighting with no UV light coming in.

I will attempt to use the method of putting some items on the coated paper and see what happens. Today is devoid of any light, but should have some results by the end of the week.

 

[Tom Taylor]

I would venture to say that the negatives are somewhere between normal and "slightly dense".

You need a dense "bullet-proof" negative. I rotary process FP4 1:1 for 24 minutes to reach the maximum density that film is capable of - 1.8 IIRC.

VDB is a print-out process. When the image "looks right" to you, then you pull it from the sun and start the washing, toning, and fixing steps. What I would recommend to you is to expose it in the open shade first and when it begins to look like what you want, finish off the exposure with direct sunlight.

Thomas

 

[ndavidson2]

You need a dense "bullet-proof" negative. I rotary process FP4 1:1 for 24 minutes to reach the maximum density that film is capable of - 1.8 IIRC.

VDB is a print-out process. When the image "looks right" to you, then you pull it from the sun and start the washing, toning, and fixing steps. What I would recommend to you is to expose it in the open shade first and when it begins to look like what you want, finish off the exposure with direct sunlight.

Thomas

Since I'm not too familiar with alt-processes yet, a "bullet-proof" negative is one that is over-DEVELOPED (and not over-EXPOSED in camera), correct? I may have a few very dense 8x10 negatives that I shot with a pinhole on xray film, but I believe those were simply over-exposed and normally developed.

 

[Tom Taylor]

Yes, over developed.

Thomas

 

[TheToadMen]

Yes, over developed.

Thomas

Indeed, but also properly exposed ... otherwise there isn't much to over develop

 

[ndavidson2]

Ok, so I finally got some sun today, and did another test. I placed a negative carrier on the sensitized paper, and then put a fairly dense 6x6 negative in the cutout. Placed in mid-afternoon sun for approx 8 minutes. Everything looked as I hoped. The unexposed part of paper was yellow, and the exposed negative was about 2 stops overexposed than what I would want in print.

Once I put it in the water to start development, the negative portion went brown, and the unexposed portion of the paper turned to a grayish brown. At this point, I ventured to say that there was an issue with what I was doing with the water.

So... lo and behold, all this time I was putting a pinch of ascorbic acid in the water bath, not citric acid! For whatever reason, I thought it was citric acid the entire time. I'm pretty certain this was the issue, however, I also use alkalized filtered water (my filtered water has a calcium thingy for my reverse osmosis unit), so I will try to do another test tomorrow to find the culprit. I was able to make a small test strip just using tap water, and my unexposed portion cleared out in the bath.

Also, I did observe that the negatives I was using earlier were most likely not of sufficient density. I'll post my final observations tomorrow hopefully.

 

[Dibbd]

So... lo and behold, all this time I was putting a pinch of ascorbic acid in the water bath, not citric acid!

Ascorbic acid is a reducing agent. That's what's causing fogging.

https://www.researchgate.net/public...as_reducing_agent_and_its_application_in_MLCI

 

[nmp]

Ascorbic acid is a reducing agent. That's what's causing fogging.

https://www.researchgate.net/public...as_reducing_agent_and_its_application_in_MLCI

Ascorbic acid - good for you, not so much for VDB.....

 

[TheToadMen]

Ascorbic acid - good for you, not so much for VDB.....

I hope you weren't switching bottles when you took your vitamines ... ??

 

[ndavidson2]

Heh, no. The ascorbic acid/Vitamin C is powdered form that I had stocked to make Caffenol. I guess the moral of this story is to READ CAREFULLY!