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Old 1st November 2010, 05:31 PM
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Trevor Crone Trevor Crone is offline
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Default PMK pyro plus

Gordon Hutchings is well-known for his PMK formula. I'm a big fan of this developer and for me it is as near to that illusive 'magic bullet' as can be.

He gives mention of PMK pyro plus which is a slight speed increasing developer without altering development times. I've been using it a bit recently on film (only sheet film to date) that I know has been underexposed and will increase film speed by about 1/2 stop. The results are indeed rather pleasing, good shadow detail without blown highlights.

Solution A

distilled water t0....................200ml
metol...................................2.5g
sodium metabisulphite.............5g
pyrogallol..............................25g
distilled water to make up to....250ml

Solution B

distilled water to...................400ml
sodium metaborate................125g (I've reduced this slightly from the published formula so all of it dissolves and stays dissolved at room temperature).
water to make up to..............500ml

A working solutions consists of 1 part solution A + 2 parts solution B + 100 parts water.

The above is the standard PMK pyro for PMK pyro plus just add a pinch of amidol (I use about 0.1g per 250ml of working solution) immediately to the working solution just before development and make sure it is fully dissolved, amidol dissolves easily. Develop film as normal, no extended development time is needed.

The above is mentioned in Anchell's 'Darkroom Cookbook'.
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Old 2nd November 2010, 07:35 AM
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Thanks for the posting Trevor this looks interesting so filed for future possible use.


Neil
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Old 2nd November 2010, 07:57 AM
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As metol isn't something I can share a room with do you know if their is an alternative formula that doesn't use it?
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Old 2nd November 2010, 08:38 AM
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Quote:
Originally Posted by Dave View Post
As metol isn't something I can share a room with do you know if their is an alternative formula that doesn't use it?
Not that I'm aware of but will look around.
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Old 2nd November 2010, 08:55 AM
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Dave, the majority of published formulas for 2 bath pyro developers don't use metol - it may be worth experimenting with one of these and amidol to see if it provides a speed increase. The amidol just increases the activity of the developer. There may be a 'magic bullet' just around the corner - it just needs some experimentation
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Old 2nd November 2010, 09:00 AM
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PMK was my 'magic bullet' for a good few years, it's an excellent developer.
I then tried Sandy Kings Pyrocat HD that uses pyrocatechol and find it has less base fog and a different stain colour and no Metol Dave.
The choice of film developers is very subjective and most are fine, if your happy with your negatives stick with it.
Thanks for posting Trevor.
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Old 2nd November 2010, 12:20 PM
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Quote:
Originally Posted by Dave View Post
As metol isn't something I can share a room with do you know if their is an alternative formula that doesn't use it?
I think the standard Prescysol is free of metol, but the EF version does contain it. You would be better asking Peter Hogan though to confirm it.
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Old 25th March 2011, 09:15 AM
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Trevor when you mix PMK formula what precautions do you take? I have read some of the info on pyrogallol and it makes you nervous. The airborn dust concerns me. Obviously nitrile gloves are a must and eye protection, but where do you mix, in the open air? with a mask?
I would be worried that if I mixed in the darkroom it would leave a fine powder in the air even with the extractor going.
I am guessing that once mixed the liquid developer doesn't hold the same problems for breathing the vapour?

Neil
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Old 25th March 2011, 11:30 AM
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Neil, I prepare the developer concentrate in my darkroom and the only personal protection I take is wearing nitrile gloves. Airborne dust should not be a problem if you measure/weigh small quantities at time using a curved spatula, taking one's time. The solid is gently poured into a deep beaker so that any dust is hopefully confined within the beaker. For example I use 600ml glass beakers to prepare 125ml of developer concentrate. However wearing a dust mask is a sensible precaution.

I wash my work/preparation area thoroughly afterwards.

As you rightly say the liquid developer is not such a risk with regard to airborne particles. Just be aware that solid particles can form around the neck and stopper of the concentrate bottle, therefore I occasionally wipe this with a damp paper towel when I see particles forming.
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Old 25th March 2011, 12:10 PM
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Thanks for the additional information I am looking at mixing some of my own in the future.

Neil
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