Pmk pyro I don't understand

[James_Spain]

I'm confused about Pyro and need some help.

Part A = 100 ml
Part B = 100 ml

Formula = 1 + 2 + 100mm H2O

That means I am left with extra 50ml Part A wasted?

How much active formulary do I need for 5x4 sheet and can I reuse developer again after staining?

I try unblinkingeye and cabbagetown sites but its not clear to me.

Thanks.

[IanG]

So if you make it from scratch yourself you jusy make twice as much Part A as Part B. These developers are one shot and PMK needs enough to cover the film so that's tank dependent unless you use trays.

Ian

[Robbie Shymanski]

Isn't PMK mixed 1+2 in liquid form?

[Chauncey Walden]

I use 300ml per 8x10 or the equivalent 4 4x5s. Strictly 1 shot. Part B is the easy one to make so when you run out of it, just make some more.

[ROL]

I'd use 1000 ml (1L) developer for 4X5 in trays, using at least one size larger than the film (I use 1500ml for 5X7).

1+2+100 would be 10ml (A) + 20 ml (B) + 1000ml (distilled) water. I know, it's really 1030ml total solution – good enough for government work.

Given your initial stated volumes, that means there's enough 'A' for 10 one-shot development cycles, and 'B' for five. PMK is usually packaged 1 to 2 volumes of A and B to account for normal 1:2 mixing ratios.

[Sirius Glass]

With Rollo Pyro, solution A and solution B are kept separate.

Use solution A and save it after the first use.
Use solution B and discard the used solution B after use.
Use solution A if you want to use it for staining and then discard the used solution A.

Both solutions A and B are one shot chemicals and should not be kept after use. The unused solutions are saved for future use. I only mix enough of each solution for the immediate processing and keep store the undiluted chemicals for future use.

Steve

[Doremus Scudder]

PMK use:

First, you do need the 1+2+100 for basic development. I mix 515ml of PMK for up to six 4x5 negatives in a deep 5x7 tray. That means 5ml A + 10ml B + 500ml water.

Don't mix up the entire amount as you would for other developers. PMK is designed to be mixed just before use and discarded immediately afterward. It does not keep more than about 30 minutes after being mixed. Mix just the amount you need for each batch. When I develop 30 negatives, I mix 5 batches of PMK, one for each batch of six negatives, in succession. I.e., mix developer batch 1, develop (stop-fix-etc.), discard old developer and mix developer batch 2, develop...

I use syringes to measure the stock solutions, adding them to the water by squirting them in from slightly above the surface to avoid contamination and carry over. Syringes are dedicated to their respective stock solution. Of course, they are carefully cleaned after use.

You need to know that pyrogallol, the main developing ingredient in PMK is toxic. DO NOT breath or touch the dry chemical when mixing (less critical if you buy the pre-mixed liquids). Use nitrile gloves and a dust mask for mixing the stock solutions. You should use nitrile gloves for developing as well. Clean up all spills immediately and thoroughly. Occasional contact with the working solution (e.g., a drip on the skin, a hole in a glove, etc.) is not overly dangerous as long as you limit your exposure by washing immediately. There were those who used their bare hands in pyro developers in the past, but why risk your internal organs?

If you are mixing PMK from scratch, just make twice as much stock solution B. If you are purchasing kits, either dry or liquid, the proportions are already 1:2, so you should have no problem. The stock solutions have a very long shelf life as long as they are not contaminated. The solution A should be a straw color. If it turns dark brown, it's dead.

If you mix from dry chemicals, either from scratch or from a kit, you MUST use distilled water for solution B. It's a good idea to use it for solution A too, but not as critical. If you do not use distilled water for solution B, the entire amount of the chemical will likely not go into solution and precipitate out. I found this out the hard way .

FWIW, solution B is only sodium metaborate and water, and the chemical is readily available from various sources, so it pays to have some on hand, especially if, like me, you find you need to use more solution B for expansions (I use 1+5+100 for N+ developments).

Oh yeah, one more thing. Many used to advocate a 2-minute soak in the used developer after fixing to increase the formation of the pyro stain. This is now thought to only contribute to overall staining and no longer recommended.

If you need more info about PMK, get Gordon Hutchings' book "The Book of Pyro."

Best,

Doremus Scudder

[James_Spain]

Thanks everyone. Im, making up from scratch but my maths isn't good.

When part A forms some gray silver crystals in the white powder mix its still useful?

For tech pan 5x4 its not staining heavy. rollo pyro or
Others - are these any better for stains?

Thanks

[Jay DeFehr]

510-Pyro is a better developer, in my experience, and much easier to use. In the interest of full disclosure, I formulated 510-Pyro, but I've made the formula freely available, and I don't earn any money by anyone using it.

510-Pyro is a single solution developer, meaning you simply dilute it with water to make a working solution, like you would with Rodinal etc. I could post the list of other advantages enjoyed by 510-Pyro over PMK, but the list would be long. Instead here's a link for developing TP in 510-Pyro:

http://pyrostains.blogspot.com/2006/...n-film_17.html

Good luck!

[James_Spain]

Thanks Jay your formula looks much easier thanks.

What down images looks like compared to pyrogallols negative s?