Pd prints not washing with EDTA

[rkbrooks]

Well, I've made my first few Pd prints from 4x5 contacts. That was

really neat. I suppose I've spent too much time manipulating bits

lately- it's such a contrast to have something to hold in your hand,

that you made!

 

In any case, I've made my test prints and gotten what I think is a

decent exposure. However, I can't seem to get the yellow out of the

highlights. I'm using the B&S Pd starter kit which uses EDTA. I'm

doing three washes of 5 min, 5 min and 10 minutes (and higher, to try

to clear)- but I'm still getting yellows in my highlights. I think my

dynamic range would improve if I could get closer to the paper white.

 

Do I need to change to HCl? Very long wash times? Uncoated areas of

the paper sharpely contrast, so the paper isn't getting yellow.

 

I'm using RO/DI water also, so it's not that my water chemistry is

screwing things up.

 

Thanks for any advice.

[clayh]

Straight EDTA-tetrasodium is pH positive. Used alone, it will mostly just lock in the unused ferric oxalate into your paper fibers permanently. I would suggest you to two things: 1) leave your print in the developer for 5 minutes and agitate gently. This will clear a lot of the ferric out of your paper, and 2) go buy some Kodak Hypoclear, and mix it up. It is normally diluted 1:4 for use, but I would recommend 1:3 and add 1 tablespoon of the EDTA per liter and mix it up. Use this for 5 minutes in three separate clearing baths. When the last bath starts to pick up a faint yellowish tinge, toss bath #1, make #2 the new #1, make #3 the new #2 and mix up a fresh #3. This is very effective on most papers. Keep an eye on the time in each bath, because it can actually begin to bleach prints if they are left in too long. Rinse thoroughly, and you should be fine.

[rowland_mowrey]

Clay;

 

I don't understand what you mean by tetrasodium EDTA being pH positive.

 

All pH values are positive from 0 - 14. The value of 7 is neutral pH and below 7 are acids, while above are bases.

 

Na4EDTA is slightly alkaline or a solution of it has a pH higher than 7. EDTA itself is acidic. By the comment made by Ryan, it is unclear what form he uses, but the alkaline form would surely form Iron Hydroxides in the coating and leave a yellow stain.

 

OTOH, I have coated a heavy enough layer of Pd that I have left a yellow stain just by having coated so much ferric oxalate.

 

Using Na2EDTA (Disodium EDTA and adjusting pH to about 5 might help out. IDK. I would hesitate to make a suggestion before I knew more of what Ryan used, and then I would have to try it myself.

 

Ron Mowrey

[clayh]

Ron,

 

I apologize for my chemical slang/imprecision. What I mean is that EDTA tetra is slightly alkaline - i.e. a value larger than a neutral pH of 7.0. The alkalinity will make the residual ferric oxalate in the paper fibers insoluble. EDTA disodium is acidic, i.e. pH less than 7.0 , and is actually what I use for my first clearing bath. EDTA-disodium is not what is normally given to people in the platinum palladium kits.

[clayh]

Ron,

 

Also, I forgot to mention that he said he was using the B&S starter kit - and I know that they don't even stock the EDTA-disodium. Another possibility to let him use what he has to make some homebrew hypoclear : 1 tablespoon sodium sulfite, 1/2 teaspoon sodium metabisulfite 1 tablespoon EDTA-tetra per liter of water. This will be slightly acidic and will clear most papers. As will citric acid @ 1-2% or phosphoric @ 1-2%, or even 1% HCl (although it is nasty stuff that should not be used if you plan on using any sodium sulfite in later baths, since any residual acid can liberate sulfur dioxide gas, and make you a very unpopular person around the house)

[rkbrooks]

I'm going to try adding the hypo clearing agent to my EDTA washes and I'll get back to you guys.

 

Thanks for the info on EDTA and the longer development times. I'll post results.

[rowland_mowrey]

Guys;

 

I have only found one thing to remove iron stains from paper. It is one of the dequest sequestrants, either Dequest 2001 or 2010. You have to bring it to an acidic pH value say around 4 - 5. Bathing stained prints in this can remove iron stains sometimes.

 

I am not familiar with the B&S kits, so I didn't know, but it is strange to me to supply the tetrasodium salt knowing that iron salts can precipitate.

 

The dequests work by having a complexation coefficient with ferrous and ferric ions that is higher than EDTA. They are very powerful sequestrants.

 

Ron Mowrey

[rkbrooks]

Well, I changed my development time to 5 minutes and added hypo clear to all the baths. This did the trick, my highlights are white!

 

Unfortunately, since I changed two variables at once, I don't know if one or both made the improvement. For now, both changes are part of my process.

 

Thanks again!

[peter_mcdonough3]

I have been using "Lime Away". It is for pipes encrusted with mineral deposits. It works much better than EDTA, et al. The dilution is 25ml/L of water. Three five minute baths after an initial washing with water does the trick.

[don_bryant1]

What a coincidence to run across this thread this evening since I've run out of EDTA disodium but have plenty of EDTA tetra. I knew that EDTA tetra makes an alkaline solution but wasn't sure how to change the pH lower than 7. Thanks to Clay for his helpful answer.

 

I am curious to know more about dequest sequestrants, or Dequest 2001 or Dequest 2010.

 

First, Ron can you tell us more about this chemical. Is it easy to purchase and is it a cost effective choice? Also in what manner do you make it acidic.

 

Thanks, to all,

 

Don Bryant