Re:PT/PD

Terry King (101522.2625@CompuServe.COM)
22 Nov 96 18:54:05 EST

Pietro

Ciao

>.But I was just trying to awoid sizing,

It will give improvements so that when you compare prints on sized and unsized
paper you will want to size however much you hate it.

> I have seen you use deionised ossein by Croda colloids.

It isa gelatine made from hoof and horn so it is hard. It is free of metallic
contaminants so it can be used for making photographs. It is 260 Bloom deionised
limed ossein. There is almost certainly an Italian manufacturer but Silverprint
and Bostick & Sullivan bothsell it.

>>Vary the proportions of platinum to palladium to give contrast control .
>>Potassium chlorate gives too much risk of ugly grain.

>I know I can achive contrast control through the percentage of PT/PD but I
>dont want to loose the chance to control the color of the print, so i think
>I have to use another contrast agent , may be Sodium Dichromate and K Oxalate?

Humidify the print before exposure and the palladium will print black.

>Use three baths of EDTA disodium salt 5 % solution

What is wrong whit Hipo ?(I dont want to be nasty , I just want to
understand why chose one product and not another one) at the moment Hipo
seems to work well for me but if you have a specific reason to avoid it, the
information is welcome.

I dd not say avoid hypo clear. You were worried about the yellow. In my
experience a good wash after development in potassium oxalate and then clearing
in EDTA gets rid of the yellow. Some people then use a further bath of hypo
clear and others a bath of citric acid. They all work.

>For negative you mean in camera negative or what?

The FP4 in camera neg is the ideal but not always practical.

> I'm starting from already existing negatives, so i have to get through
>positive and then final big size negative. I chosed Tech.Pan for the
>positive to get no grain,(if properly treated can a be long scale film too)
>and for the final neg (i want to rich prints bigger than 8x10) i must use
>Agfa N31P or Agfa GO21OP ,because i dont think i can find any other film so
big.

I have used Kodak Gravure Positive and Kodak Separation Negative 2 for
enlargements. Anything else above 10 x 8 apart frpm FP4 is a compromise. I have
also used Dupont film that have worked well. It is a matter of subjective
judgement whether one finds the results of the compromise acceptable. Not many
of these films are still made.

>About Amidol are you referring to the Wenston's paper developer or the
>Amidol wather bath negative developer?

Not if you are spending money ! It is cheaper to buy the chemicals yourself.
The paper developer works well but there are film developers that work a little
bit better.

> I have no experience of Amidol

I will send you instructions.

>and unfortunately i have also the problem that everithing i use for no silver
process cames from abroad , i mean to find the right product it is not
easy.

Try looking in the catalogues of Italian Chemical suppliers or asking a friend
who teaches chemistry. I know that there is a good company in Firenze selling
non standard photographic materials . Try Milano anfd Firenze where printing
companies may be disposing of materials for photo mechanical printing.
Florentines on the list may be able to help with addresses. Silverprint (Fax
0171 620 0844 ) sell a wide range of materials but sometimes there are
difficulties in sending themoutside the UK. You could also try Bostick and
Sullivan in the US.

>What is PQ universal? whic brand?

PQ is an Ilford film and paper developer availablein Italy. For PT/ Pd prints,
as Bob Schramm says, over expose the FP4 by two stops and develop it at 1 : 9
for 2 m 15 seconds.


>I do agree . I understand the smoother is the paper the best is the
>sharpness but dont forghet the sensual pleasure of a heavy and textured
>paper

A beautifully sharp and gradated print can also give sensual pleasure. Try
sizing the textured papers.

>. For sharpness what about vaacum printing
frame?

I use two sheets of 6 mm glass. It works well. I believe a vacuum frame is an
over complication but there are others who will disagree who will give you
alternative methods.

> whic brand is Waterford?

Waterford is made by

St Cuthberts Mill
Wells
Somerset
England

BA5 1AG

UK

The Company have Italian distributors.

Here is a note on amodol that I posted to thelist in June:

"You asked for an amidol recipe. This is the explanation of the film developer
that I posted to the list:

"The recipe Ron quotes is the standard paper recipe. It is stunningly effective
especially when a liberal dose of potasium bromide is added which will warm up
paper tones. It also improves the keeping quality if about an eighth of the
amount of sulphite is replaced by potassium metabisulphite.

I know that when I placed a sheet of Kentmere Classic Art in the developer it
came up in the same wat as a platinum print would in potassium oxalate. The
print in terms of tonal range and separation of tones within narrow ranges was
almost enough to bring me back to silver gelatine.

But for film it is better to use the acid amidol recipe.The recipe is from the
Illiffe Dictionary of Photography fourteenth edition. A dictionary I read from
cover to cover like a novel.

This is a translation from imperial to metric;

Boiled water (important) 570 ml Sodium Sulphite (cryst) 43 g Sodium Sulphite
lye 35 ml Amidul 4 g potassium Bromide 0.3 g

For the lye

Add 15 ml of sulphuric acid to 200 ml of water and then stir in 115 g of sodium
sulphite until it is dissolved.

This should be enough for three or four 10 x 8s.

The seventeenth edition of the dictionary says that ' it is the only common
developing agent that will develop in acid solution'.

'N' for both is about ninety seconds.

Keep your fingers out of it unless you want to look as if you smoke sixty a
day."

Hope that this helps.

Ciao

Terry king