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Newbie DIY C-41 Recipe/Formula/Process


Yes, I have struggled with this myself. I had to titrate my batch of FeCl3 40% solution because nobody could tell me. A search for "Ammonium Thiosulfate 60% solution" at least gave me enough hits mentioning "w/w" to assure me.

PE once told me: "you can weigh much more accurately than you can measure volume, therefore chem manufacturers prefer w/w". I took this as a hint to assume w/w except where stated otherwise.
 

now i have only 400 grams that 96% powder of Ammonium Thiosulfate... can you tell me how to mix it with this ammount?
 
emkei said:
now i have only 400 grams that 96% powder of Ammonium Thiosulfate.
Click to expand...

So assuming 60% w/w, your 400g are 60% of the total weight, which would make the total weight 400/60 * 100 = 667g. Add 267g water to your 400g thiosulfate.

Btw, I second the comment from @Rudeofus about ending up with a milky liquid. In my experience, it's milky with some yellowish sludge floating on top. I always filter it through a fine mesh cloth a couple of times to get rid of it.
 
A while ago I had asked the local chemist about dry ammonium thiosulphate - they had it in stock but the price was hellish. Also, the store warned me that ammonium thiosulfate is stored very poorly - it quickly begins to disintegrate, probably from there the sediments. At the same time, the price for a 60% w/w solution is very low and there was no problem with storage. Unfortunately, the minimum orders were a thousand liters. I ended up getting 5 liters of 60% solution from Suvatlar for 45 euros, which contains over 4 kilograms of dry thiosulphate equivalent.
 

Perhaps you should look at the right place. I buy it as a fertiliser at 1, 5 and 15l bottles. The 5l ones cost about 20€ nowadays. 1l cost me 7€ back in July.
 
Anon Ymous said:
Perhaps you should look at the right place. I buy it as a fertiliser at 1, 5 and 15l bottles. The 5l ones cost about 20€ nowadays. 1l cost me 7€ back in July.
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I searched - I called 4-5 importers, talked to agrarian pharmacies. The first require industrial quantities, and the others do not provide ATS as an independent product, but only in combination with nitrogen fertilizer... I'm just tired of arguing - they just don't understand me for what purpose I want it.
By the way, I visit Greece from time to time - if I can get it directly from somewhere convenient for me, that would be great
 
Thanks. I'll look, but I still have stock at the moment
 
hi guys, i want to ask how many films can i develop with this developer? is 20 enough? or can I try a little more?
 
This is a formula with rounded weights close enough to the patent. But with a missing chelating agent - this implies a shorter shelf life. Although it can last months with luck. Personally, I would use it for 4 rolls per liter.
 
I used the first batch on 20 rolls with good results. now with the second batch I'm already on 18 rolls. I was just curious...
I extend the developing time by 2% per film
 
Tetenal's instructions provided C-41 CD times for up to 16 rolls per liter, and if you are willing to really stretch it and are willing to do some corrections in digital post, you can easily get up to twice that.
 
I extend the developer time, like I said before by 2% per roll. i extend the fixer time just slightly - 10 min for the 20th film (from starting point 6.5 min)
and I want to ask about bleach, because there I use 3 min with no change. it is OK?
 
emkei said:
I used the first batch on 20 rolls with good results. now with the second batch I'm already on 18 rolls. I was just curious...
I extend the developing time by 2% per film
Click to expand...

How long did it take you to develop these 20 rolls? For me, the problem is actually the time, not the amount of films...
 
within 2 months i guess. three months would be my limit
 
emkei said:
I extend the developer time, like I said before by 2% per roll. i extend the fixer time just slightly - 10 min for the 20th film (from starting point 6.5 min)
and I want to ask about bleach, because there I use 3 min with no change. it is OK?
Click to expand...

While you immediately recognize poorly developed C-41 materials, incomplete fixing will hit you with a vengeance some years down the road. At the same time neutral fixer is easily available outside of packaged kits, so there really is no reason for stretching fixer to the limit.

Regarding bleach: it lasts seemingly forever. If you use it, it gets reduced, and aerial Oxygen will bring it back. While Oxygen will restore the oxidizer in your bleach, it raises pH, and at higher pH your bleach will become slow to ineffective. If you have no pH meter, then I recommend the "fizzle test" to check, whether your bleach is still acidic and therefore active: add a few grains of Sodium Bicarbonate (aka baking soda) to your bleach. If the grains start fizzling (=releasing Carbon Dioxide), you bleach is good. If these grains don't fizzle, then add some acid: battery acid, acetic acid, swimming pool "pH down", whatever you can find to get pH down far enough, that more grains of bicarbonate will fizzle again.

Another factor affecting bleach is dilution: every time you carry over washing water into your bleach, you effectively bring water into your bleach. This will dilute your bleach as you keep reusing it. Since the only way to correct for that would be "add fresh bleach concentrate", and since "fresh bleach concentrate" is not as easily available as "neutral fixer", you have to plan for longer bleach times even if you restore acidity of your bleach.
 

Hello I am trying to follow your recipe, how much sodium sulfite in the stop bath part should I added?
 
About 10 grams - has a purifying effect. However, you will need a pretty good wash before bleaching. If you use standard DTPA C-41 bleach, it is not so important.
 
lamerko said:
About 10 grams - has a purifying effect. However, you will need a pretty good wash before bleaching. If you use standard DTPA C-41 bleach, it is not so important.
Click to expand...

Thanx bro I will try the recipe then
 
This is a simplified formula - I haven't tried it, but it will probably work. It's pretty close to patent.
 
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