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Traditional PL / PT Formula

TRADITIONAL MIXING SENSITIZER FOR PAPER: DATE FERRIC OXALATE BOTTLES AS YOU MIX THEM

total # of drops will increase as image size increases.
Also number of drops for any given image size will vary due to paper thickness and absorbency of paper. I like to coat with alot of emulsion- some people feel a thin coat is better......

My starting point:
8X10 = 30 DROPS     16X20 = 130 DROPS

When mixing sensitizer, use these figures as a starting point- Multiply number of drops needed by the following:

Sol 1 is Ferric Oxalate, the light sensitive stuff
Sol 2 is ferric Oxalate and Potassium chlorate the contrast control agent for the emulsion bad stuff- more later
Sol 3 is the metal Palladium, Platinum or a mix of both.
FOR VERY SOFT NEGATIVES (HARD PAPER GRADE 5?
SOL 1: 0
SOL 2: 0.478
SOL 3: 0.521
FOR SOFT NEGATIVES (GRADE 4?)
SOL 1: 0.174
SOL 2: 0.304
SOL 3: 0.521
FOR AVERAGE NEG(GRADE 3?)
SOL 1: 0.304
SOL 2: 0.174
SOL 3: 0.521

EXAMPLE FOR 30 DROPS:

0.304 X 30 = 9.12 DROPS

0.174 X 30 = 5.22 DROPS

0.521 X 30 = 16.63 DROPS

FOR MODERATELY CONTRAST NEGATIVES (GRADE 2?)
SOL 1: 0.391
SOL 2: 0.086
SOL 3: 0.521
FOR VERY CONTRASTY NEGATIVES (SOFT PAPER GRADE 1?)
SOL 1: 0.478
SOL 2: 0
SOL 3: 0.521
Note: solution 2 from Bostick and Sullivan is labeled ferric oxalate #2 or ferric oxalate#2(pt). You use (pt) only with pure platinum. Platinum is more contrasty than palladium so the #2(pt) has less potassium chloride which makes it a less contrasty #2. Good idea to mix all chemicals 12 hrs. before use. Be sure to wait until the Ferric oxalate solution is clear!
If there is a residue in the bottom of palladium solution #3, you can add small amount ( a few grains) of normal table salt to the liquid to get everything back into solution. Or heat up chemicals sightly. If there is a residue in platinum heat bottle and shake do not add salt! Remember that when you use palladium and platinum in combination the total # of drops changes as a sub-formula to the sol 1, sol 2, sol 3 formula IE: 10-0-10 (5pt.-5pl.) changes to 8-0-8 (4pt.-4pl.) for a 50% Platinum Palladium Print with no #2.

MIXING OF FERRIC OXALATE AND PALLADIUM FROM POWDER
Wear respirator! I think it is best to buy in powder and mix yourself.

FERRIC OXALATE
27 grams to 100 mls distilled water
plus 2 grams oxalic acid
heat water to quite hot
add ferric oxalate and oxalic acid
mix well it will look like dark pea soup when first mixed
I like to mix the night before I print but you may use it as soon as cloudiness disappears, about ½ hour

PALLADIUM
55 mls distilled water
5 grams palladium chloride
3.5 grams sodium chloride
dissolve salt first!
heat water to quite hot
add salt and stir well
add palladium

Date ferric oxalate as it does not have a long shelf life once in liquid form one to three months max! You may add a few drops of hydrogen peroxide in an emergency but best to throw out if unsure. It will keep longer in refrigerator. Perhaps 1 to 2 months longer. As it goes bad you will begin to notice fogging in your highlights and a loss of contrast. In powder form it lasts for years, or so I'm told. Palladium will last forever in power or in liquid.

As to droppers- they make a tool called a pipette- device for measuring liquid. With a "pipette pump" attached you can measure out and dispense liquid so much faster and more accurately than with droppers. The are cheap and easy to use. Everyone who has tried them stops using droppers. With 2ml 1/10 ml gradation pipettes 1 drop = 1/10 ml. see suppliers list. For larger prints go to 5 ml pipettes and 5 ml pumps

I have found that double coating does help dmax and bronzing problems as well as often giving you a richer print. My method is to coat a single coat, let it dry fully- in my darkroom about 20 mins then apply the second coat. I use the same amount of solution for both coats but if I am using TWEEN I reduce by ½ the amount of TWEEN in the second coat. During the summer months- higher humidity I use 10% more solution in the 2nd coat. Most negs will print fine with a single coat but double coating is something to keep in mind.