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


  1. Excellent! We've been so buzy we forgot this golden nugget!
    Details in both snow highlights and in the deep shadows, hard to top this.......

    1. Remeber that I used a high quality camera. :-)
      The Ensign Selfix 16/20.
      That may explain the high level of detail and great tonality. :-)

    2. AH, british boffins at work, I have one myself, as you know, nice little camera, but not german optics?

  2. Interesting ... definitely makes it easier to use in a similar vein to PC-TEA. It's kind of funny that we spend all this time/effort on various ascorbate devs only to realize that the original PC-Glycol works extremely well. I remember posts from Patrick Gainer where he tried something similar but he ran into some strange pH issues. I'll have to try this one.

  3. I discovered that Sodium Metaborate (NaBO2) will also dissolve in glycols. In fact, metaborate converts ascorbic acid into ascorbate while in the glycol, which has higher solubility. That lets you dissolve much more ascorbic acid into the glycol, making the concentrate more concentrated. For example, PC-Glycol has 14% ascorbic acid (w/v). But if you add some metaborate, you can add more ascorbic acid, even over 50%.

    Also, I didn't know that NaOH will dissolve in glycol. That's useful for a concentrate, because it's a concentrated form of strong alkali.

    1. vwery interesting Mark and thank you, this merits further investigation.....