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Re: Rejuvenating old Ilford plates
Posted: Fri Feb 17, 2017 9:31 am
by walschuler
Right--quite possible.
Regards to Joy.....Bill
Re: Rejuvenating old Ilford plates
Posted: Sat Feb 18, 2017 10:16 am
by jeff-blyth
I have found that old Slavich plates that have never been exposed to any light, can darken to a density well over 1.0 in fresh developer in less than a minute. This fogging effect can be rectified as Martin says in this thread, by using weak Fe EDTA bleach and then after rinsing, use vitamin C solution at about pH 5 to resensitize the plate. However in the case of Ilford plates , your comment about getting a density of 1 and seeing a faint image and nothing at higher density, suggests that the situation may be different. What density do you get roughly when you develop a piece of old Ilford plate without exposure?
Re: Rejuvenating old Ilford plates
Posted: Tue Feb 21, 2017 7:18 am
by walschuler
My usual bleach is "Wesly (Phillips) No 3": 12 grams Ferric Sulfate, 12 grams disodium EDTA, 30 grams potassium bromide, and 50 grams sodium bisulfate in 1 liter of distilled.
My redeveloper is just 10 grams of ascorbic acid per liter of distilled.
What dilution and soak time for the bleach would you suggest?
What would you add to adjust the ascorbic PH and what soak time would you suggest for that? (I have to get PH strips!)
I will try D19-developing an unexposed plate before I go farther...
Re: Rejuvenating old Ilford plates
Posted: Wed Feb 22, 2017 5:25 pm
by jeff-blyth
In the case of old Slavich plates I got rid of the fogging by immersing plates for 1 minute in the following solution using Fe EDTA from Sigma. This post is for anyone with old Slavich plates .
20g Ferric EDTA and 10 g KBr per litre. (This solution keeps for a long time.)
(Ferric EDTA is ethylenediaminetetraacetic acid ferric sodium salt also called iron (III)sodium ethylenediaminetetraacetate hydrate cat. no 03650 Sigma-Aldrich
However as you are using a made up Fe EDTA this may not be quite the same, but I suggest cutting down on the potassium bromide to 10g per litre.
I then re-sensitized the plates in 2% ascorbic acid brought to pH between 5 and 6 using NaOH.
The plates (PFG-03) behaved AS GOOD AS NEW!
I have never tried it on old Ilford plates. If you do not get a density as high as 1 from an unexposed plate after about 30 sec in your dev then if the darkening is only mild (say 0.2) I suggest just the above resensitising soln. will probably help.
Re: Rejuvenating old Ilford plates
Posted: Sun Mar 05, 2017 9:19 am
by walschuler
We developed a supposedly unexposed plate, right out of the box, 2 minutes in D-19, and it darkened to OD around 2.
We then tried taking another and soaking it in our stock ferric EDTA bleach for a minute, then rinsing, then in stock ascorbic acid redeveloper (10gms/liter) (see emaIl above) for a minute, dried it, exposed for 20 seconds, then developed in the D-19. No image was visible and the OD was
only around 0.1, very underexposed.
We used stock chemistry because we were lazy. Perhaps that is the problem. But the theory of this sequence eludes me. I could see the bleach working as it should rehalogenate the silver, but then why develop after with the ascorbic?
Re: Rejuvenating old Ilford plates
Posted: Mon Mar 06, 2017 12:35 pm
by dannybee
Ops
Re: Rejuvenating old Ilford plates
Posted: Mon Mar 06, 2017 6:46 pm
by dannybee
dannybee wrote:walschuler wrote:We developed a supposedly unexposed plate, right out of the box, 2 minutes in D-19, and it darkened to OD around 2.
We then tried taking another and soaking it in our stock ferric EDTA bleach for a minute, then rinsing, then in stock ascorbic acid redeveloper (10gms/liter) (see emaIl above) for a minute, dried it, exposed for 20 seconds, then developed in the D-19. No image was visible and the OD was
only around 0.1, very underexposed.
We used stock chemistry because we were lazy. Perhaps that is the problem. But the theory of this sequence eludes me. I could see the bleach working as it should rehalogenate the silver, but then why develop after with the ascorbic?
Hi Walschuler.......my thinking here would be not that the silver was rehalogenate but if the dye was next to the crystal. in other word the sensitivity may be ther but maybe not the dye that extends the sensitivity, test exposing it to white light are you get any response in uv and blue... and if you do, then its simple add the dye in the rehalogenate bleach or a bath afterwards... its a idea to try to see wants happening
Re: Rejuvenating old Ilford plates
Posted: Tue Mar 07, 2017 4:02 am
by Martin
Maybe there was too much EDTA bleach left in the layer.
The last time I tried this method I used a diluted bleach (1:10 or so).
I understand the ascorbic acid step is meant to hypersensitize ("reduction sensitization" I assume) the emulsion.
Re: Rejuvenating old Ilford plates
Posted: Thu Mar 09, 2017 12:33 pm
by walschuler
Further progress(?)
1) as per suggestion above pre-soaked (30 secs) a plate in FeEDTA bleach diluted 1:10, then normal ascorbic 10mg/liter, exp 20 secs, devo D-19 2 mins, plate OD is about 1.8, which is good, but no image
2) as in 1 above, but exposure 15 secs, OD is about 2.2 (! higher at lower exposure ???) and no image
both 1 and 2 bleached clear but no image
3) on the theory that only the re-haolgenation is needed, tried just the dilute bleach presoak, exposed 15 secs, OD 0.8-1.0, no image
4) checking that the no-image results were not a setup stability issue, exposed a new PFG-01 plate, exp 15 secs, OD was a bit low at 0.3, but there was a decent image, so stability is not the problem, as I have assumed from prior experience
Keep in mind all the Ilford plates come out of the box completely clear under the green safe light.
I can not see an orderly explanation for all this. Wonder if further adjustments to concentrations or pre-soak times might help. IDEAS???
Re: Rejuvenating old Ilford plates
Posted: Thu Mar 09, 2017 5:48 pm
by Din
Bill,
Try a simple two-beam grating. I'm not convinced that chemistry is the answer. I'm beginning to veer towards a lack of the ability to take a large spatial frequency spread.This could occur for several reasons:
1. Emulsion has thinned
2. Emulsion has cracked
3. Emulsion has lifted from the base, ie delaminated.
As you know, an actual image needs a large range of spatial frequencies, but a two-beam grating records only one.
If the problem is 1. or 2. then recording only one spatial frequency should give you a diffraction, albeit weak. If 3, then it depends on the amount of delamination. If the delamination is not too serious, a recording of a single spatial frequency might yet give you something.