Weston Diploma question

deisenlord · Sep 17, 2007

I've been using Weston Diploma and notice when my Potox is hotter than 120 degree is looks like it defeats the sizing in the sheet and completely saturates its. I haven't noticed any adverse effects other than the final dried surface may loose some of its smoothness and it doesn't dry as flat. Are there going to be any other long term adverse archival effects of this? Should I avoid this? I like very warm images so like my developer hot.
Thanks,
Ike

wilsonneal · Sep 17, 2007

This is what I noticed as well, and ultimately it's why I stopped using it.
n

Robert Hall · Sep 17, 2007

Same here.

clay · Sep 17, 2007

I use this paper for workshops because it is so forgiving. But the last thing I want is newbies slopping around hot developer, so I always use cold-bath developer, which will give you very nearly the same warmth as hot pot-ox even though you keep it in a tray at room temperature. The only downside to this developer is that it gets murky and black a lot more quickly than regular pot-ox, so I end up tossing it sooner. But if you make your own developer from potassium carbonate and oxalic acid, all you need in addition to make cold bath is some potassium phosphate monobasic. The cool temperature of the developer will keep your sizing from being fried.

deisenlord · Sep 17, 2007

Perfect Clay, will give this a try!
Ike

deisenlord · Sep 17, 2007

Do you have a formula for the cold bath ?

clay · Sep 17, 2007

I will look this up tonight and confirm, but I am pretty sure that it is :

150g potassium oxalate
75g potassium phosphate monobasic
and water to make 1 liter of developer

Normally I just mix up all my potassium oxlate developer from scratch, so i have a lot of it in a gallon jug. Its nominal composition is 250g of potassium oxalate per liter. 150/250 = .6, so I add 600ml of regular pot-ox (already mixed) 75g of the potassium phosphate monobasic and then top off to 1 liter of solution.

Will double check all this tonight at the house.

deisenlord said:
Do you have a formula for the cold bath ?

clay · Sep 17, 2007

I was off slightly. I have edited the formula with the 'correct' proportions. Although you would be surprised at how insensitive this process is to things like developer dilution.

bill schwab · Sep 17, 2007

Thanks for this Clay!

eggshell · Sep 24, 2007

Hi Clay,

Does the PO formula with pot phosphate monobasic change the contrast & printing speed as compared to standard PO?

Also, what is the formula to mixing my own PO from Potassium Carbon & Oxalic acid? Do they need to be lab grade? I remember a post not too long ago but couldn't seem to find it.

Thanks a million.

clay · Sep 24, 2007

No, it doesn't have to be lab grade. Here is the recipe from Eric Nielsen on the alt list, which is the one I use:

2 lbs of Pot Carb with 1.75 lbs to make 1 gallon of water. 1 lbs = 457
g and 1 gallon = 3.8 l ( top of my head but close enough as it is just POT
OX).

Mix your Pot Card into cool distilled water; about 1/2 your total volume.
SLOWLY add your Ox Acid as it WILL BUBBLE!!!!. Add to completion and top
off with water to make final volume.

Do this outside. It releases a lot of carbon dioxide. Not poisonous, but can displace all that nice oxygen filled air your lungs desire.

eggshell said:
Hi Clay,

Does the PO formula with pot phosphate monobasic change the contrast & printing speed as compared to standard PO?

Also, what is the formula to mixing my own PO from Potassium Carbon & Oxalic acid? Do they need to be lab grade? I remember a post not too long ago but couldn't seem to find it.

Thanks a million.

eggshell · Sep 25, 2007

That does it! Thanks again Clay.

Weston Diploma question

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