Friday, March 23, 2012

Taking PC-glycol one step further.

The basic PC-glycol developer is easy to mix.
70ml glycol.
12.5g sodium ascorbate
0.25g phenidone.
Top up with glycol to 100ml.

I used concentrated engine coolant. This is ethylene glycol with a few additions
that doesn't inflict on the workings of the developer.
This concentrate has a shelf life of several years.
This concentrate is to be used in a 1:50 dilution.
Make a liter of water containing 5g washing soda or 1.7g of sodium hydroxide and 6.1g of borax.
This is part B.

For a 300ml tankful take 6ml of the concentrate and 294ml of part B.
For a 500ml tankful take 10ml of the concentrate and 490ml of part B.
Starttime is 8 minutes for 100 ISO B&W film.

This is a bit awkward. It is easier to just dilute with water.
Reading about borax and why borax is used in antifreeze,
I started to wonder if it is possible to add borax to the PC-Glycol solution.
Well, it is. Ethylene glycol can dissolve more than 40% borax at 25c.
It can also dissolve a small amount of sodium hydroxide.  That lead me
to this recipe.

Glycol 70 ml (Ethylene glycol in the form of concentrated engine coolant)
Sodium ascorbate 12,5 g = about 10g ascorbic acid.
Phenidone 0,35 g
Borax 20 g
NaOH 4 g

Top up with glycol to 100ml.

Heating the glycol a bit made it possible to dissolve the ingredients.

Use concentrated anti-freeze for car engines.
Use the blue ethylene glycol stuff. Not the "green" or non-toxic or low-toxic versions. Do not use the red long-life version either. The blue old-fashioned concentrated ethylene glycol works ok. You can use the cheapest you can find. They contain less "snake oil".

Diluting 1:20 with water gives a developement time of 6.5 minutes
for ISO 100 B&W film.
pH is 10.9 in the working solution.
Diluting 1:50 with water gives a develoopment time of 8 minutes
for ISO 100 B&W film

pH is just below 10.9

It is possible to add sodium sulfite to the developer when diluting.
Use 60-100g/L for a solvent action.

Sample images:
 Shanghai GP-3@100 ISO
 Shanghai GP-3@100 ISO

Tuesday, March 20, 2012

Creating a XTOL clone.

I have been reading about XTOL and the clones with names like MyTol and Instant MyTol.
The concept is interesting, but none of them except XTOL has any substantial shelf life.

There is some recipes that specifies mixing a concentrate in TEA, but TEA isn't available over here, so we have to either make a concentrated developer in ethylene glycol AKA concentrated engine coolant, or just mix the working solution in a bottle.

I have tried with ethylene glycol engine coolant and it works great, besides that sodium sulfite can't be dissolved in EG.

This time I choose to mix in clean water.
The goal is a developer that performs close to XTOL.

Mix as this:

Water 700ml
Sodium sulfite 75g
Ascorbic acid 12g
Dimezone-S 0.3g
Borax 25g
Boric acid 12,5g
Fotoplex-2 1g AKA Fotoplex-2 or Dequest 2010
Kbr 0.1g
Benzotriazole 0.03g
Water to 1000ml

The resulting pH should be 8.2

This recipe contains Dimezone-S instead of Phenidone. I have to use 1.4 x the phenidone amount to get the same activity. 0.3g Dimezone is about the same as 0.21g Phenidone.
The rationale for using a bit more Phenidone/Dimezone-S than the MyTol recipe is that developing one roll of film uses up about 0.015g phenidone. I want to have the possibillity to develop more than 10 films in one liter of developer without running into exhaustion problems.
I also use a bit more sulfite than MyTol. This to push it into the solvent developer segment. It also helps keeping the grain fine.
Benzotriazole is added to keep fogging on old outdated films to a minimum level.
If fog still is s problem, the amount may be increased to 0.05g, but not more without loosing film speed.
Using benzotriazole reduces the need for KBr, but including 0.1g helps the contrast a bit and helps avoiding bromide drag.
Etidronic acid, 1-Hydroxyethylidene-1,1-diphosphonic acid, CAS.Nr. 2809-21-4 AKA Fotoplex-2 or Dequest 2010 is added to avoid the XTOL sudden death syndrome.
According to experts, this is THE ingredient to stop the sudden death of ascorbic developers.

Tests so far shows an activity level on par with D76.

Shanghai GP-3 needs 8.5 minutes @22c, Agfa APX-100 needs 8 minutes @22c.
100 ISO B&W films like Fomapan 100 needs about 6 minutes@22c
Use as D76. Either reuse and add 6% time for each film or dilute 1+1 to 1+3 and use as one-shot.

Sample images.

 Shanghai GP-3 @100 ISO. 8.5 minutes @22c. No adjustments other than rescaling to smaller size.

100% crop from previous image. The image is scanned at 4800DPI.
There is hardly any grain visible. No adjustments, no sharpening.

Agfa APX 100. 8 min @22c. Contrast increased a tad due to overcast weather and very flat light that day.