alternative C41 Bleach formula?

[mohmad khatab]

At risk of being accused of passing gas in church, here is another contribution to C-41 bleach alternatives.

The two images attached are negative scans from Portra 160NC 35 mm film processed identically save for the bleach. After developing (alternative C-41), and stop bath and rinse, I snipped off a few frames of the MacBeth chart and then completed processing the two samples using the traditional Fe-EDTA bleach for one and the copper bleach formula I mentioned above for the other. Bleaching was done to completion by inspection at ~100F temperature (7 minutes for the iron bleach and 10 minutes for the copper), followed by a rinse and the usual fixer/wash/stabilizer.

The copper bleach is the 100/100 g copper sulfate/salt per liter that I mentioned above. The images are negative scans made with Nikon LS-9000ED at 600 dpi. To the eye the negatives have nearly identical appearance.

My conclusion is that if the stimulus works as well as copper bleach we will soon be in pretty good shape. I am not advocating replacing conventional bleach formulae with the simpler one, but for those who cannot afford or locate components for iron bleach it does work. Who knows about long term dye stability? All I know is that these negatives haven't faded in the last 12 hours.

I totally agree with you, the copper bleach has been severely oppressed for many years.
It is time to regain his dignity and pride.
The cheapest ovary in history:
But I discovered a number of important issues that should be available:
With regard to the story of copper bleach, I discovered the following:
1. Copper sulphate is available in two types.
A - The normal type (binary) Cas # 7758-98-7
B - There is also the type Quintet Hydrate Cas # 7758-98-8
The difference between the two types is also large and the difference in price is the first item at $ 1.5 per kilo and second at $ 9.4 per kilo. In fact, the original formula was the second type. But the first type is the most common type of market.
* Generally. I have deepened the study of this article and this subject and I have now realized and know why the author of the original formula says that the formula suitable to whiten the number of 5 rolls only.
- I also know why Mr. PE says that copper bleach leaves some transparent red spots on negatives at times.
- You can use the first cheap article, but the amount must be multiplied by 3 times and 0.7 (ie we add 370 grams instead of 100 grams - and also salt sodium chloride)
And then we do the work of filtration and purification of the solution, and then we follow your indirect method of controlling the pH.
- On the whole I will try that plan and I will follow you with the results,
- These conclusions did not come by coincidence, but came after reading many scientific articles, and I learned that the degree of melting copper sulfate in water is 36 grams per 100 milliliters. After doing some inaccurate calculations I learned that this plan would be successful.
Finally - the best results come if deionized water is used and the bleach should be filtered with a piece of medical cotton using a funnel.
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