Found Unopened Pyrocat and TF-4 Should I Use It?

**Brian Bullen** · 8-Aug-2007, 20:51

Cleaning out a cabinet in the darkroom and way back behind some chemical bottles I found some unopened pyrocat hd and a bottle of tf-4 fixer. I'm guessing these are from 2005, so a little over 2 years old. Should I just chuck 'em or give it a go and hope for the best?

**Andrew O'Neill** · 8-Aug-2007, 21:19

Is the pyrocat-HD a kit? Pre-mixed? If it's pre-mixed I'm sure it's no good especially solution A. Is the fixer stock solution?

**Brian Bullen** · 8-Aug-2007, 21:28

Hey Andrew, the pyrocat is in liquid form so sounds no good, The TF-4 is stock solution and there is separation in the bottle. Whitish color on the bottom and clearer on top. I've never used TF-4 before so I'm not sure if this is normal.

**Dean Cookson** · 8-Aug-2007, 22:08

That's normal for TF-4. It stays in solution once you dilute out 3:1 for working strength. I'd mix it up and see how long it takes to clear a piece of film.

I mixed up some from 18mos old stock this weekend and it cleared in ~15-20s.

On the pyrocat front, what's solution A mixed in? If it's glycol, I bet it's fine. If it's water, I'd be very surprised if it was still good.

**Daniel_Buck** · 8-Aug-2007, 23:40

By coincidence, I was looking up on this the other day (about it's capacity, though). According to the Formulary, TF-4 "should not be kept for more than 12 months" in stock solution form. Not sure if this means it's lost most of it's effect by then, or if it just begins to loose it's effect after 12 months.

**IanG** · 9-Aug-2007, 01:16

If the solution A of the Pyrocat HD is still a nice light colour it should be fine. It goes reddish brown, then brown if the Pyrocatechin has oxidised.

**Brian Bullen** · 9-Aug-2007, 19:36

Thanks for the replies, I guess I'll just give them a try and see what happens. The pyrocat was mixed with water so I'll check the color before i try to use it. I've got some film tests planned so the fixer could get used on that without worry about archival quality.

**sanking** · 9-Aug-2007, 20:40

Originally Posted by photobulley

Thanks for the replies, I guess I'll just give them a try and see what happens. The pyrocat was mixed with water so I'll check the color before i try to use it. I've got some film tests planned so the fixer could get used on that without worry about archival quality.

If the liquid kit from Formulary was mixed in water, but has not been opened, I suspect that it is still good. You could test quickly by mixing equal parts of A and B and taking a small leader of film of exposed film and dunking it in the developer for a a few seconds. It should slowly turn dark. If it does not turn dark, no good.

My understanding is that all Pyrocat-HD and -MC kits now being sold are mixed in Propylene Glycol. These kits should be good for at least 5-10 years.

Sandy King