Decided to take a closer look at Pyrocat-HD, various dilutions & continuous agitation

[koraks]

1. My Pyrocatechin - looks like crystals - dark gray in color.

Going by the photo, I'm going to hazard a guess that it wasn't dried entirely during manufacturing and retained some water, or somehow got a little moist over time. But that's a wild guess. I agree it doesn't look the greatest. The sludge in the concentrate is a bit odd; perhaps there are other impurities as well. The greyish color of the flakes is weird; catechol tends to be more brown in my experience.

3. Color of the concentrate - pale reddish. Almost colorless.
4. Color of working solution, ratio 1:1:100. Colorless.

Looks normal to me. I get the same. Concentrate is very pale reddish and if pulled into a very thin syringe like yours in the photo, it's nearly colorless. In a bottle, it's more pale red.

5. I put several pieces of film for about 15 minutes - even after the first one, it turned yellow.

I would suspect the yellow is part of the sensitizing and anti-halation dye package of the film that washed out into the developer. The subsequent color change might be normal oxidation of the developer, which is indeed orange/brown.

your working solution should be a light peach/straw appearance, not clear.

Mine is clear as well.

Here's my concentrate (part A) in glycol to the left, and a freshly mixed working solution 1+1+100 in tap water to the right:

 

[lamerko]

I won't think so for now. I'll scan the first sample tonight, do another one with proper measurement and fresh film. But I'm really surprised by the 30 year old Ilford - there's no hint of fog and the sensitivity hasn't dropped much either. I found it in an old loader, it hasn't been refrigerated...
About the color of the working solution after processing - as far as I can tell, it is not from oxidation - it is caused by dissolving of dyes from the film. In the picture above, I had cut pieces of old technical film - Kodak 2498 RAR. Like most technical films, this one has a "strange" emulsion color - a strange greenish...

 

[John Wiegerink]

Take care John! By the way, I'll be uploading a video about 2-bath Pyrocat-HD on the weekend.

Andy,
That 2-bath video would be great. I'll make a big batch of popcorn and grab a soda, then sit down and enjoy your video. Might even top it off with a donut!

 

[Andrew O'Neill]

Andy,
That 2-bath video would be great. I'll make a big batch of popcorn and grab a soda, then sit down and enjoy your video. Might even top it off with a donut!

 

[Ian Grant]

My working solution usually turns very slightly greenish in places when I add Part B then clears to almost colourless when mixed. Post development the colour is very dependent on the film stock processed green, quite dark blue, yellow, orange, quite a range depending on the anti-halation dyes used.

Ian