Pyrocat-HD Stock solution shelf-life

[Ron Marshall]

Would anyone know the shelf-life of unopened Pyrocat-HD stock solutions A and B?

[j.e.simmons]

I mix my own rather than buy the commercial products. I've had solution A as long as six - seven months in an amber glass bottle before using it all. I don't use solution B (I just add the carbonate directly to the working solution) but I suspect it would last as long. I don't know if they will last as long in plastic as glass.

juan

[Ken Lee]

I purchased some inexpensive glass balls, and add a few now and then to each bottle, to raise the level and keep out extra air. Cheaper than a special collapseable bottle, they make it easy to stir up the solution without introducing more air.

[sanking]

Ron,

Stock Solution A should last a year or more in a partially full bottle. In a full bottle even longer. I have a liter of control Stock A that was mixed over three years ago and it still works fine. If Stock A were to go bad prematurely, say from contamination of some of the B stock, you would know it because Stock A would turn brown.

Stock B will last indefinitely.

Some people mix Stock A in glycol, which should make it last for five years or more. I mixed it that way myself a few times to make sure it worked, but have since gone back to mxing it water since I generally use up a liter or more every three months or so.

Sandy

[Eric Rose]

I'm still using stuff mixed over 2 years ago. Great stuff.

[Ken Lee]

Try some in a little Orange Juice: It's dee-licious !

[Walter Foscari]

"Some people mix Stock A in glycol, which should make it last for five years or more..." Sandy, do you mean sobstituting glycol for water? Where do you obtain that? same mixing procedures?

Thanks
Walter

[sanking]

Walter,

Most people use propylene glycol. I purchase it from http://chemistrystore.com, but I believe that places like Phtographers Formulary and Artcraft also carry it.

Yes, same mixing directions. You mix as with water, except you must heat up the gly col first to about 150F for the pyrocatechin and phenidone to dissolve. Place the glycol in a pyrex container and heat in a water bath over the stove. Once it heats up to 150F add the pyrocatechin, stir until is dissolves, then add the phenidone. Mix the sodium metabisulfite and bromide separately in a small container of hot water hot, then when dissolved add this to the glycol solution containing the pyrocatechin and phenidone. This solution will have about the same permanece as a HC-110 stock solution, which is to say for a very, very long time. Use it just as you use Stock Solution A mixed in water.

No point to do this with Stock B since it will last indefinitely anyway.

You could also substitute ethylene glycol, available as anti-freeze, but I feel more comfortable with the propylene glycol since it is found in many foods so should be very safe

Sandy

[robert_4927]

I have pyrocat in liquid form, from B&S. The A solution is a dark, almost like coca- cola color. Is this A soluting Bad?

[sanking]

Robert,

I have never used the B&S Pyrocat-HD kit and don't know how it performs or what it looks like, or how it performs. I have used the kit from Formulary, and it mixes up with a very clear Stock A solution, perhaps with a hint of a pale yellow, just as my Stock A looks when mixed from scratch. And my Stock A solutions keeps this color indefinitely. In fact, the three year old control bottle I have is still almost completly clear.

Is there any possibility that you may have contaminated Stock A with a minute quantity of Stock B? If so, the result would be a very gradual shift in color of Stock A from clear to light amber to darker amber to coffee brown to dark brown. Beyond light amber I would not trust the solution.