blue prewash from shangahi film

[miss_emma_jade]

a friend pointed out that if you washed the shaghai film ive been using, you get a deep blue dye off it. i hadnt been prewashing, and and hadnt really noticed my developer getting blue. i cant see much difference either way , but wondering if anyone knows if its best to wash this out first or just develop?

emma

[vinny]

all films have a different color that comes off in the prewash. I think it's a good habit to do so and there are a few reasons I won't get into here since that info has been posted in the past.

[Lachlan 717]

When you consider that pre-washing only takes a few minutes, I guess the question for me is, "why wouldn't I"?

Also, for some processes and/or developers, pre-wash is strongly recommended (some Pyros, for example).

[miss_emma_jade]

I just thought that it may have affected negative density or exposure when it was removed, pre washing isn't a hassle, and I will do it from now on..

[IanMazursky]

I remember the beautiful blue color when i processed the shanghai film.
Ive always thought the different AH colors where so cool.
I use a 1-2 minute pre wash in my jobo to take care of the AH dyes.

[Lachlan 717]

I just thought that it may have affected negative density or exposure when it was removed, pre washing isn't a hassle, and I will do it from now on..

Also a good way to bring the tank/tray/film up to/down to the desired temperature...

[Liam:]

Fomapan has a turquoise green colour, I always wash it before developing just in case. I read that you are not meant to wash ilford films as they have a layer which helps drying.

[Lachlan 717]

I read that you are not meant to wash ilford films as they have a layer which helps drying.

Wouldn't this wash off in a) the developer, b) the Stop Bath and/or c) the fixer just the same as in the presoak?

[Shen45]

Pre washing film will alter the end contrast of the negative, and it will vary with film brands. The AH dye has no affect [detrimental] if left to go through the developer. As has been stated Ilford no longer advise a pre wash. If you are concerned about uneven development load the film into the developer tank with the developer already in it. In the dark of course.

If you are happy pre washing your film though - and - you don't see any issues with how your negatives are developed then naturally go for it. It doesn't really matter.

[Ari]

I always pre-wash Shanghai, only for one minute, in a Jobo tank, and it's given consistent results that way.

[D. Bryant]

I just thought that it may have affected negative density or exposure when it was removed, pre washing isn't a hassle, and I will do it from now on..

If you are happy with the results you are getting now don't concern yourself with pre-washing.

If you want to experiment give it a try and compare your results.

This topic has been discussed in every internet film forum that I've ever been a member of and prior to that in the dial-up days at CompuServe.

Don Bryant

[miss_emma_jade]

well, I've been using shanghai a while, (maybe 4-5 boxes) and developing in D-76 one sheet at a time in a patterson tank. Slow... So a friend developed some for me when I went home on holidays, and used a uniroller machine and rodinal ' and prewashed. That's when I saw the blue dye. I think these negatives were a little bit short on contrast. I've since bought and set up my own uniroller, and last night I prewashed, and think the negs aren't really lacking anything in contrast. Maybe its the rodinal? Any ideas?
EMMA

[D. Bryant]

Any ideas?
EMMA

Print or scan the negatives and evaluate.

[Tim Povlick]

Your 1'st question about why the blue die doesn't show up in the developer when not using a prewash is a good one. I do not have the answer other than to guess something in the developers cocktail of chemicals neutralizes the pigments. I have observed this same effect with other films.

As to thin negatives in Rodinal on the Uniroller, perhaps the developer "bombed out" and exhausted / oxidized before the end of the development time. I always use a full liter of developer in Jobo drums that spin on a DYI base. Pyro will look very oxidized long before the development time expires. It's been a while since I used Rodinal but I believe it is the same. I've learned to spin the drum by hand slowly (like 10rpm) when using these sorts of developers. You may wish to try Xtol 1:1.

Good luck & Best Regards,

Tim

[Cor]

Your 1'st question about why the blue die doesn't show up in the developer when not using a prewash is a good one. I do not have the answer other than to guess something in the developers cocktail of chemicals neutralizes the pigments. I have observed this same effect with other films.


Tim

Most likely the AH dye as also a pH indicator property. A pH indicator will change color upon a change of pH, but it could alos change in a colourless state (or vice versa).

I guess this dye is blue in water (more or less neutral pH around 7.) and colourless in the developper (alkalin, roughlypH 8.0 and up)

Best,

Cor

[Tim Povlick]

Hi Cor,

I hadn't thought about that; very intriguing!

Thanks for your response.

Best,

Tim

[Rayt]

I just developed two sheets of Shanghai 5x7 in HC-110 without pre-wash and the developer after 8 minutes was the same shade of yellow as when I mixed it. The Ilford fixer was also clear. I guess the blue dye got neutralized somehow.

[Liam:]

Rodinal goes turquoise when you develop fomapan without washing.