Fantastic blacks! Is it Tmax 400?
I changed to PC-512 Borax as linked in post 1.
Start times seem to be about 6.75 m 20C for T-max 400 EI=400 and 7m 20C for FP4+ EI=125:
I changed to PC-512 Borax as linked in post 1.
Start times seem to be about 6.75 m 20C for T-max 400 EI=400 and 7m 20C for FP4+ EI=125:
It was this film explained by Peter Elgar. I believe it sold out pretty quickly though.
Very nice result, @Alan Johnson !PC-512 Borax seems to be quite a good push developer, here is one at double the recommended ISO with 30% increase in development time:
PC-512 Borax seems to be quite a good push developer, here is one at double the recommended ISO with 30% increase in development time:
PC-512 Borax seems to be quite a good push developer, here is one at double the recommended ISO with 30% increase in development time:
I tried test 1 formula above with 20g/100ml as suggested by @relistan. Call it PCM20.
PCM20 one shot concentrate:
Propylene glycol ..............80ml
Sodium metaborate.........20g
Ascorbic Acid......................12g
Phenidone ...........................0.5g
Propylene glycol to....... 100 ml
It can be made in a container partly immersed in very hot water. The ingredients dissolve with stirring at 60C , with some effervescence around 50C.
For use dilute 1:50 with tapwater.
The viscosity is low and it is easy to syringe and mix.
Results of developing Fomapan 100 @ EI=100 for 4m, 6m and 12m 20C are attached.
Here is a test shot developed for 6m 20C:
I believe @albada found 15g/100ml metaborate in glycol was stable after 4 years [did not crystallise], here using 20g/100ml.
I did try the formula with only 12g/100ml metaborate but at 1:50 the negatives were extremely thin after 12 min development.
It seems that 20g/100ml is a good compromise.
Photoformulary and Fototechnik Suvatlar list sodium metaborate.
I used Sodium Metaborate Tetrahydrate, CAS10555 76 7.
Please note my post of Aug 6 2024, PCM20 is not stable and loses activity, I stopped using it.
It seems likely that the phenidone is oxidized in presence of the water of crystallization.
It is not possible to say for sure but it may also be that some oxidation of phenidone occurs during the heating of the original mix when making the concentrate, thereby lowering activity.
This loss of activity was only found during the investigation of the mix and I now recommend using the original two part PC-512 Borax linked in post 1 as the PC-Glycol in that does not contain any water and appears more stable.
yes, I did notice that post, I wondering if adding salicylic acid can make it last longer, or heating the Sodium Metaborate solution to remove the water.
when you find that PCM20 loses activity, does its color change?
I think it's still a good formula if I use it up in one month or so.
BTW, what is your normal dev time?And what film do you use?
I thought that since it is mixed in Propylene Glycol, it would remain active indefinitely...
yes, I did notice that post, I wondering if adding salicylic acid can make it last longer, or heating the Sodium Metaborate solution to remove the water.
when you find that PCM20 loses activity, does its color change?
I think it's still a good formula if I use it up in one month or so.
BTW, what is your normal dev time?And what film do you use?
Developed a roll in this batch of PC-512 Borax that I’ve left sitting in its jar (in the dark) since February 2023. It’s a bit yellowed but dev time was exactly the same.
The fact that the Fenton reaction did not destroy the ascorbate over that 1.75 years of sitting indicates that both your water and chemicals contain little iron and copper impurities. The fact that PC-512 Borax contains no sodium sulfite helps reduce these impurities.
Mark
Yes, there’s no water other than whatever minute amount was dissolved in the (food grade) propylene glycol. The ascorbic acid powder and phenidone seem to be quite clean. The ascorbic acid is food grade stuff from German eBay that I bought in bulk about 13 years ago. I’m still using what’s left of 25g of phenidone I bought from Bostick and Sullivan in 2014 when I lived in Portland. The water and borax (20 Mule Team) only meet the developing agents at dev time and don’t have enough time to do much damage. That was part of the reasoning. It’s nice to see that it’s working out as expected.
Have anybody tried PC-512 Borax to develop Pan F? If so what should be the development time?
I don't know of anyone who has. I use 10-15% _less_ than XTOL stock times for most films. So e.g. Kentmere 100 is 8 minutes in XTOL, so I use 6:45 or 7. Delta 100, same time. ADOX Silvermax is 7 minutes so I use 6 mins.
Pan F has an XTOL stock time from Ilford's docs of 6.75 mins. So as a starting point, I would suggest that 6 minutes will be fairly good.
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