Saturday, June 23, 2012

Why is Dignans method a good choice?

When developing according to Dignans method a certain amount of the first bath, where the color developer (CD-4) is, will be transported to the second bath, where a basic solution will permit the development to take place. But this bath remains uncontaminated and may be used until the volume is not enough to cover the film in the developer tank. Then you just add to this bath a certain amount of fresh solution of CD-4. I suggest to add 0,5 liter each time, so in general we may have between 500 and 700 ml of solution, witch is enough to develop not only 35 mm but also 120 films.

The second bath don't need to be stored, it is said to pour down the drain. But if you reuse it, I think it will work if the pH is about 11,6 to 11,8 or even 12. Today I made a try with pH 13 and less time, I still don't have results to show but I leave this two pictures of yesterday, developed with the same solution I already used twice. No signs of exhaustion,

No color correction at scanning

Correction with more blue and green
In general, the film I am using, Agfa Plus 100 ISO, without any correction, shows a shift to magenta when set to automatic color correction at scanning. The color shift may be caused also by the bleach bath of dichromate and sulfuric acid I am using. To be sure, I will try a classic ferric EDTA next time. This is not a very big disadvantage, ferric EDTA is available at ebay or somewhere else, you don't need to by a standard kit to get it.
On the other hand, the bleach I am using seems to last almost forever and you only need very weak solution of it for 2-3 minutes only. Like suggested by Donal Qualls, I am using a stop bath of vinager between the second developer bath and bleach, to prevent the formation of gas of bleach reacting with sodium carbonate and hydroxide.

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