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gavjenks
15-Aug-2013, 19:29
So I've seen plenty of descriptions of how to bleach off one side of the emulsion on two-sided X-ray paper, exactly how to do it, etc. But very frustratingly, in none of the dozen or two dozen descriptions can I find any mention of WHEN during development you are supposed to bleach.

Before developing at all?
Before even exposing?
After the developer but before the fix?
After the fix?

Andrew O'Neill
15-Aug-2013, 19:47
I've talked about stripping xray film here several times. Here was the last place, I believe: http://www.largeformatphotography.info/forum/showthread.php?80011-Images-shot-on-X-ray-film/page137


You do it AFTER you have developed, stopped, fixed the film and AFTER it has completely dried. Make sure you strip the side of the film that was facing away from the lens. To make sure, lay the negative down on a light table, oriented the correct way. The side facing you is the side you bleach.


Andrew

gavjenks
15-Aug-2013, 19:51
Alright, thanks.

Corran
16-Aug-2013, 13:57
I strip right after washing, BEFORE drying, which for me was easier/safer. Test it for yourself.

Dilute the bleach 1:1 though for the stripping. I find that makes a big difference.

Andrew O'Neill
16-Aug-2013, 17:16
Curious... how is it easier/safer? I've tried stripping with wet film, and you run the risk of bleach seeping to the "good" side. With dry film, you get the best seal possible with duct tape. Thanks.

Peter De Smidt
16-Aug-2013, 17:47
I'm with Corran. I bleach the back right after taking my film out of my Jobo drum. It's wet, and it sticks right to the glass. Bleaching takes under a minute, and then the negative goes in the wash. This means that the negative is only washed and dried once, which minimizes it's getting scratched during handling. It's also much faster.

Nonetheless, it would be easy to try both ways and use whichever method works best for you.

Corran
16-Aug-2013, 18:35
It's wet, and it sticks right to the glass.

Yep, this is why.

Andrew O'Neill
16-Aug-2013, 21:17
And the negative doesn't move around on the glass at all when applying bleach? Sounds risky to me, no?

Corran
16-Aug-2013, 21:19
I'm not really hip to fluid dynamics, but I've found that the 1:1 dilution with water seems to equalize things. I haven't had any issues with the bleach seeping into the other emulsion. I hold the negative in place though. No worries about scratching anyway, since you are bleaching.

Andrew O'Neill
17-Aug-2013, 09:13
Thanks Corran. What are your reasons for bleaching? Do you print on photo papers? Scanning? I only do it when I want to scan for a digital neg. There is a difference in sharpness.

Peter De Smidt
17-Aug-2013, 09:18
I had a tiny bit of bleach go under the edge with my one and only practice sheet, but that's because I bleached way too long. It's been smooth sailing ever since.

Corran
17-Aug-2013, 10:14
I do it because the BTZS tube scratches the rear emulsion often. I like rotary processing though.

Andrew O'Neill
17-Aug-2013, 19:31
Peter, how about you? Are you bleaching for the same reasons as Corran?

Peter De Smidt
17-Aug-2013, 19:59
I bleach because I'm scanning, and I get better scans with one emulsion.

Andrew O'Neill
17-Aug-2013, 22:22
Thanks Peter. That's why I strip, too. There is a very noticeable difference in a stripped and unstripped negatve, even in a quick scan.

gavjenks
19-Aug-2013, 14:53
Okay I just got my first x ray film in the mail and developed some test shots. Fuji half speed blue.

Bleach after development did absolutely nothing. Well, it sort of changed the color of the emulsion a little bit, but did not remove it. I'd be interested to know why?

However, not a problem, because I figured out a much less chemical-y and still completely effective way to remove the emulsion on one side: a toothbrush! I just pasted the negative to one side of a wet sheet of glass straight out of the wash, so that there was a surface tension seal, then I used a medium bristle toothbrush to just brush away the emulsion on the other side. Takes maybe a minute for one negative. Quite happy with the results. Whatever little bits of emulsion might make their way behind onto the other side do not seem to be hard enough to scratch the "good" side.

It might have left very small scratches on the removed side's base, though. Will have to wait and see in the scan or in the enlarger, whichever I get to first. It's very subtle. Also, I could try soft bristles next time anyway, or some other even softer brush if not that.

Andrew O'Neill
19-Aug-2013, 15:00
Don't understand why it didn't come off with bleach. You used ordinary, household bleach, correct? The emulsion should turn a brownish colour from the bleach. Brush it on with a sponge brush (or just a plain old sponge) and work it until all the emulsion has browned up into a liquid. It MUST come off with bleach.

Wayne
19-Aug-2013, 18:44
To make sure, lay the negative down on a light table, oriented the correct way. The side facing you is the side you bleach.
Andrew

Or just remember which side was up in the tray and bleach the other side.

Andrew O'Neill
19-Aug-2013, 19:41
If you are stripping wet, right after processing, then yes it's easy to know which side to strip.

gavjenks
19-Aug-2013, 19:42
Both sides have emulsions, so which side I choose shouldn't matter in terms of whether the bleach works (it should matter in terms of whether I ruin my photo, but that's a different issue).

In any case, I went back just now to try it out, and the other side doesn't come off with bleach either. I poured pure bleach on a sample negative after development, let it sit for about 30 seconds. There was no color change. I then rubbed it lightly with a rag, and the emulsion did not come off. It scratched a bit, similar to the toothbrush, but there was no apparent chemical assistance from the bleach in removing anything. I then rinsed it off and tried the other side.

After doing all of this, I can still easily see a (scratchy) complete image on the negative, seemingly completely unaffected other than by the physical scrubbing. The color of the negative base and emulsions all still show as deep blue and blacks, no brown.

I am using Fuji Half Speed Blue x-ray film,
Ilford DDX developer
Diluted vinegar as a stop bath
Ilford rapid fixer
then water, and that is all.

Andrew O'Neill
20-Aug-2013, 08:49
It's definately a mystery. You're stripping with wet, freshly processed film, correct? And it sounds like you tried the other side when it was dry, still with no luck. Is the bleach okay?

gavjenks
20-Aug-2013, 17:50
Ding ding! We have a winner.

got some new bleach at the store and it works just fine. The other stuff still smelled like strong bleach.... weird.

Andrew O'Neill
20-Aug-2013, 21:23
Do I get a prize??

gavjenks
21-Aug-2013, 00:36
I will send you a large format print of my first born.

Andrew O'Neill
21-Aug-2013, 18:02
I'll hold you to that! ;)