[RA4] Brown Blix - dead?
This morning I mixed up a litre of Kodak RA4 Blix and put it into two 500ml pop bottles.
A few hours later, after working in the darkroom, I wanted to replenish my Blix with what I made up earlier. However, the Blix had gone a muddy light brown - just like the colour of engine oil if you get water in it. It was jet black when I mixed it up.
Any idea what's going on?
It looks as if there was some sort of contamination in the bottles before you poured it in. Bleach Fix will go muddy brown when it is exhausted and smell of chlorine as well. has your blix got any smell?
It doesn't smell any different than usual. The pop bottles had water in them originally but there is a (small) chance that they held some Blix before and I re-used them. You know those round toffees in Quality Street? The Blix is that colour.
Have you tried it? It might be fine. I can't ever remember my blix being jet black. It has been a few months since I did RA4 but ifI recall correctly it was a maroonish/burgundy-brown on mixing and went more brownish after use.
The jet black bit when freshly mixed worries me more than the muddy light brown. I cannot see any reason why the blix should have gone off given what you have said.
'Jet black' is a bit of an exaggeration. But it is black - perhaps with hint of purple. Certainly not toffee coloured like now and odd that it changed colour within a few hours.
I haven't tried it yet, I replenish in a Nova so it's going to be mixed with the older Blix that's fine. The concentrates are old - the dev I bought at the same time died recently and I am about to make a new order at ag for blix.
Brown blix could be a sign of carryover from the developer. If so, the pH has gone up too high (among other changes).
Try adding some 28% acetic acid very slowly to a small test sample. It should turn red again. If it does not, then it is truly bad. If it gets cloudy, it is truly bad, but if it is clear red, you are on the right track.
The pH should be 6.5.
There is certainly something strange here. I don't think it can be carry-over, PE, as Steve is talking about freshly mixed blix, waiting in the bottle to be used for replenishment.
I know the "Quality Street" toffees of which you speak, Steve and I am sure my blix was never that kind of a brown. It always had a reddish/maroon look to it. The toffees of which you speak are very clearly an unmistakeable light brown.
Unless Quality Street toffees are available in the States the colour may mean little to him. Pity as the toffees are a "proud to be British" confection.
It is why we have terrible teeth but big smiles :D
RA4 BLIX uses ammonium ferric EDTA as silver bleach agent which gives it this purple black color. If the pH is too low the EDTA goes out of solution and releases the iron ions as iron oxide which is most likely the brown mud you see in your BLIX. So contrary to common wisdom (iron oxide forms in caustic and dissolves in acid environment) you may actually have to raise the pH with NH3. The low pH might come from the fixer component going acidic over time from oxidation. Even if NH3 gets the EDTA and the iron oxide back into solution, you still have the issue of the fixer component likely gone bad, so you may have to throw out the soup anyway.
Well, on the acid side, Ammonium Ferric EDTA turns orange in solution and if the acid is strong enough, the Ammonium Ferric EDTA will precipitate as an orange brown solid forming a cloudy blix. Enough acid will also cause sulfurization, and that will form a cloudy orange blix. Actually, Ammonium Ferric EDTA powder is brown-yellow.
The correct blix color is a beet red or blood red color, so brown is bad. I must admit that the OP was a bit ambiguous, and I misread it to imply that the used blix was brown.
In any event, a brown color indicates a problem.
To test it, you can fog and develop a piece of B&W paper, then wash and then use the blix. The B&W paper should turn white! It should do so it less than 3 minutes at 20 deg C. If it does not, then lets talk about what did happen. And, if you can, look for cloudiness and check the pH.
Apologies for misleading, my wife's got some pH strips somewhere, if I get chance today I'll check.