Sunday, May 29, 2016

Another approach to Dignan's 2-bath developer for C-41

What seduced me with Dignan's divided developer was the absence of time and temperature control when doing C-41 at home, without expensive equipment.

I am using the method for quite a while now, but I still have some in-satisfaction about colour shifts, grain, shelf life, etc..

I already tried to solve colour shifts using different recipes for bath B, decreasing or increasing pH. The grain has been always there, no matter how I agitate or not. Shelf life was 1 month for bath A and pictures were becaming weaker and weaker.

Let me remind you of the composition of bath A:

1 g of Sodium Bisulfite
9 g of Sodium Sulfite
11 g CD4
Water to - 1 liter

I couldn't get Sodium Bisulfite, but I read somewhere that Metabisulfite in 1:1 proportion would do the same. So I used 1g/l of Potassium Metabisulfite.

I tried to use more Potassium Metabisulfite, 2g/l, to prolong the shelf live and indeed, it worked. I could use the same batch of bath A during 6 months with little changes that I compensated with longer bath B until 1 hour.

The use of more Potassium Metabisulfite seems to require longer bath B anyway.

The last insight I had about the divided C-41 developer was this one: Why not helping the second bath with a little of bath A in it? This could have as result a better overall development and, who knows, better negatives?

In fact, I started using 20ml/l of bath A in bath B and then increasing to 50ml/l. Yes, better colours and better density of the negatives. And with constant agitation I had much less grain than before.

But, and this could cut to zero the advantages of Dignan 2-bath developer, if we need 50 ml of bath A for each film, after 20 films we spent 1000 ml that would also have developed 20 films without split development.

But no, bath B with 50ml/l of bath A may develop 2, 3 or more films, so making the process very attractive.

Monday, May 23, 2016

New findings on C-41

I have been using split development for color films with some success but sometimes it fails too. I like very much the idea that we just use a small amount of CD4 in the first bath and get more films developed than one could achieve with a one-bath developer.

Some causes of failure are:
  • The first bath looses strength and leads to underdevelopment
  • Different films need different second baths, different pH
    (Fuji tends for instance to give greenish negatives)
  • Grainy pictures (also because agitation is manual and sometimes we don't agitate enough)
 I am working in an alternative but I still have to test it with at least 2 other films, Kodacolor and Fujicolor normally available today.

By now, I am getting good results with Fujicolor-Eterna-250D, besides a very tolerant film that can even be developed with hair dye as I already showed here while other films give very bad results.

These pictures have a very good color in just automatic scanner settings and a fine grain.
So, as soon as I have more confidence with the alternative to the split developer, I will make a new post. By now, pacience is needed, but the idea is to include in the second bath a certain amount of the first.