Infrequent use of Bleach

[mrred]

I may develop 10 rolls of C41 a year, and now make my own chemistry to minimize the waste.

My bleach.....

Water (32C) 900 ml
Potassium ferricyanide (anh) 40 g
Sodium bromide (anh) 25 g (30g pot brom)
Water to make 1 l

It works well, but after a month or two.....it looks real dark. I've been throwing it out, not bothering to replenish it.

Today, after not doing anything for 6 months, I decided to test it. I took a film leader (B&W) and developed it in the light with Diafine (fastest). Put it in the tank and bleached it....then fixed and presto....a blank leader.

My question is, is there an easier or more obvious way to find out if the bleach is good? It looks like I have been wasting a fair amount of bleach with false assumptions. I've not been replenishing because I thought the replenisher was going bad too.

 

[Rudeofus]

First and most obvious change to your procedure would be to use slide film for the test, or C-41 film without orange mask. If you have a scanner with ICE, and your scanner software supports it, you could try using the IR channel to determine whether your negs/slides are properly bleached. But let's face it: all the companies doing real research on bleaches and BLIXes back then used xray and related methods to quantitatively test for retained silver, and all these methods are out of our reach. One could try to look for retained silver with the same methods that test for incomplete fixing in B&W work, i.e. selenium toner or sulphide toner, ...

 

[mrred]

Your method is already complicated than mine...... I was just hoping to skip the 15-20 mins to get a result. I guess this is it then. My brain hurts.....lol

 

[Rudeofus]

Allow me to tell you about some experimental data of mine, in order to show you how complicated a "simple" process like bleaching can be: if you use the bleach recipe as described (there was a url link here which no longer exists), you will end up with medium brown slides unless you also use the prebleach. If you mix a bleach from part of a BLIX kit (see my article) instead of straight Ammonium Ferric EDTA, it will bleach alright without a prebleach, since BLIX kits have a suitable bleach accelerator in the part containing the Ammonium Ferric EDTA. If you use too much of that bleach accelerator in your bleach, you're back to square one with brown slides.

No test known to me, short of trying a test clip, will reveal this. Therefore I can hardly imagine a reliable test for your bleach. The good news: you don't really have to test a bleach beforehand, since if it doesn't work, you can always rebleach and refix some time later without risk to your precious images.