Sunday, January 29, 2012

Pushing the process Caffcol

As I announced in the last post, the process I am working on will be called CAFFCOL for simplicity of speach. I came to the formula given in that post by trying and adjusting, according to some experience with caffenol. I have been using the proportion 1:2 for soda and coffee when developing B&W films. Caffenol without vitamine C takes some 45 minutes time to develop at tap temperature, witch is about 15 ºC here where I live.
I remember that once I developed a color film with coffee and vitamine C and I could see some vestiges of color there. This is one of the photos:

Color film developed with Caffenol-C, image treatement with GIMP

That was the reason why I started to develop color films and I choosed the Tetenal Colortec kit to start because it is more easy for beginners like me.
After some color experience I decided to try then with coffee, just to see if I was right about my former conclusion, that there was a little color on that film.
Indeed, I might have not been mistaken. If we add CD4 to coffee and soda, we have a color developer. It is not the «non plus ultra», of course, but it is starting now.
Today I made two changes in the process. I tried to put less soda, because I am working with a ph near 12 and this must be lowered to less than 11. Unfortunately I still don't have a ph meter, I will look for one at the pets (aquarium) shop tomorrow. But I made a solution with just one tsp soda, 2 tsp coffee and 10 ml CD4 solution. Image loss definition and I remembered that this also happened when I putted no coffee. OK, I repeated with one tsp soda, 4 tsp coffee and 10 ml. With this, I obtained a better negative and the results, after treatment with GIMP are better than the other, I got less grain, maybe because the ph was lower (I also added some drops of lemon juice, eheheheh).

Color film developed with Caffcol, image treatment with GIMP

Color film developed with Caffcol, image treatment with GIMP

Meanwhile I tried to develop some stripes of negative in Caffcol at tap temperature and then fix to see how long it takes until the silver becomes black. I came to the conclusion that 20 minutes was the best and because the color process takes place at higher temperature, maybe less than 20 minutes would be enough. But if developing in 40 minutes is OK, we don't get over-development, then I tried with 20 minutes. Resuming, the last recipe has changed to:
1 tsp sodium carbonate, aka washing soda
4 tsp coffee
10 drops of lemon juice
10 ml CD4 5% solution
water to make 500 ml
In this formula the lower ph gave less grain, more coffee to produce more definition and because the amount of water decreased, it has comparatively more CD4 and coffee than the other, see previous post.
To be continued...

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