Testing RA-4 Blix
I have some blix that I mixed up six months ago. I know that it does deteriorate with time. However,
how do I know for sure whether it is still useful or a toss-up? I've been thinking of running a piece of RA-4 paper
through the blix (without developer) and then after a wash dunking it into the sulfide toner to see if there is retained silver.
Good idea? Bad idea? Anything better?
Blix does have a long shelf life even after mixing. I have found that it will take on a milky appearance when it has 'gone off' or is exhausted and has a noticeable change in smell too. So if it is still a deep burgundy colour, with no milky appearance it should be OK. If what you have is in a bottle it should be shaken vigorously before using.
I use a Nova deep tank processor and yesterday I drained the 3 slots and washed them out. The BLIX was still clear and active but there was a thick layer of sulphate at the bottom, deposited during the life of the solution even after regular replenishment. The dev & stop bath were OK, but full of tar and after cleaning, the solutions were simply poured back in and topped up.
Usually I will look for sulfation sludge in the bottom of the storage bottle. If it is not severe, and sulfation products are not distributed throughout, I will test it witha piece of unexposed RA paper - it should come out white. I have had blix run, with replenishment, but a few months between used for more than a year.
Thank you Mike and BMbikerider! You have confirmed my experience. My impression was always that Blix lasts quite a while in an airtight container. However, some recent posts in apug that blix starts to go off soon after mixing have made me very concerned. My main worry about blix is that I would not be able to tell immediately when it's not working since retained silver would show up much later after the print is washed, dried and hung on the wall for a few weeks. Thanks guys, you made me feel better.
The best thing to do, and this applies to all photographic solutions, is not to exceed either the recommended shelf life or capacity. Write down when a solution was made and the number of films/sheets run through it. So with good record keeping there is no need to test.
Originally Posted by BMbikerider
May I ask what you cleaned your Nova processor with? Thanks!