Fixer Question

Dichromated Gelatin.
Tony

Fixer Question

Post by Tony »

The last few outings I have had an issue in the fixing bath.
I noticed that it took a very short amount of time for my plate to clear.
Normally it is 20 seconds or so to start clear and then sometimes fully clear at around 30 seconds but the last few batches of plates its been starting to clear closer to 6-10 seconds.
I am fairly sure my film is the same thickness, in fact I made it a tad thicker.
I had some 2 month old pretty grey fixer bath and it cleared quickly. I mixed some fresh fixer and still fast.
Laser energy the same
Temperature and humidity about the same
I tryed new film (a day or two) and some older film
I can't go broadband very easily as a result, the film is either milky or shifting green.

Is there another variable that I am missing???
holomaker
Posts: 772
Joined: Wed Jan 07, 2015 8:01 am

Fixer Question

Post by holomaker »

Hi Tony, when you say "clear" as in the yellow turns clear? I assume you are shooting in blue light. is it possible your concentration is full strength? i found when shooting with blue light vrs green the fixer need to be diluted like 300% from the original concentration......... has it been a while since you were doing DCG?
Johnfp

Fixer Question

Post by Johnfp »

Hmmm...Weird. Milky indicates underhardened and Green points to over exposed. What would do that?
Thinner film would lower fixing time which may cause underhardening. WHich if you kept all parameters the same (exposure time) it may cause the film to be over exposed.

Try to forget about clearness and try keeping it in the fixer for the ususal 30 - 40 seconds.


Gelatin Bloom is important. DId that change or same batch/lot?
Are you sure you didnt accidently add to little gelatin or too much water in the emulsion fabrication? It may be, don't waste your time on this batch and just make another batch. Or compensate with lowering exposure time.
Tony

Fixer Question

Post by Tony »

holomaker wrote:Hi Tony, when you say "clear" as in the yellow turns clear? I assume you are shooting in blue light. is it possible your concentration is full strength? i found when shooting with blue light vrs green the fixer need to be diluted like 300% from the original concentration......... has it been a while since you were doing DCG?
Yes Dave it is my blue laser and yes I am looking at when the film clears the yellow. I haven't diluted my fixer before but wow really 300%. Can you explain why? Does the blue light really harden the film that much? I've still shoot but mainly perfecting how to make DCG masters, now trying BB.
Johnfp wrote:Hmmm...Weird. Milky indicates underhardened and Green points to over exposed. What would do that?
Yes exactly John, it doen't make sense...
Johnfp wrote:Try to forget about clearness and try keeping it in the fixer for the ususal 30 - 40 seconds
Doing this gives me a green hologram, but I will try lowing the exposure maybe that will help
I am pretty sure my water Gel is OK since it has been on two different bacthes of film. Bloom hasn't changed that I know of.

Hey look at us, talking DCG :D
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