Cyanotype solution lifespan?

[ChristopherCoy]

I have some B&S cyanotype solution bottles that I bought a number of years ago. They have been stored inside my office for the last few years (at least 3). What is the typical lifespan of these solutions? Would they still be good?

 

[koraks]

The individual solutions are quite stable provided they were stored in the dark and in a reasonably cool environment. Verify the color of the ferricyanide solution (the yellow/orange one); it should be a bright color and not a more muted/brown color. The green solution should be translucent and free of any dark strands floating about the place. This also should be of a pure, saturated color; if it has discolored into a blackish mess, it's toast.

the last few years (at least 3)

That's the grey area in my experience; hit & miss. Look for the signs indicated above.

Also, if the solutions look reasonably clean and the way they originally did, just try and make a print on a paper you know performs well with the process. The print should clear readily and there should be no printing out occurring all by itself. The latter is evidenced by the paper remaining a light, lime color after sensitizing and drying but prior to exposure. It should not discolor towards a darker green or even blue tones, and it shouldn't take on a blotchy appearance.

 

[fgorga]

I have some B&S cyanotype solution bottles that I bought a number of years ago. They have been stored inside my office for the last few years (at least 3). What is the typical lifespan of these solutions? Would they still be good?

The potassium ferricyanide solution should be just fine.

The ferric ammonium citrate solution may have grown some mold. If this is the case filter it through a coffee filter or even a paper towel and it should be just fine.

These solutions are very stable. I've kept solutions for similar time periods and they have been just fine. These days I add small amount of thymol to the ferric ammonium citrate solution and haven't needed to worry about mold since starting to do this.

A test is simple... mix a small amount of each solution together in a 1:1 ratio, dip a piece of paper into it, let it dry in the dark. It should be yellow at this point... greenish at this point means either that paper is not suitable or the solutions are bad.

Then expose the paper to a UV source for awhile. If all is well, the paper should turn blue/gray and when washed in plain old water it should be dark blue.

 

[ChristopherCoy]

Thanks yall! They’re in white bottles and have been stored in dark cabinets since I got them. And they’ve always been in climate controlled environments. I’ll check them out over the weekend!