Kallitype - Fogging

[UKJohn]

Having had a gap of a few years from making Kallitypes I am revisiting the process working on a personal project, previously I've had reasonable success albeit with a number of issues along the way. I ordered some new ferric oxalate (from Wet Plate Supplies in the UK), mixed this up as per their instructions - 20% sol. 10g ferric oxalate, 1g oxilic acid and 50ml distilled water, it took a long long while to dissolve, when it did even after 48 hours it hasn't cleared and is dark green/brown in colour. I'm sure previously ferric oxalate I made up did go reasonably clear.

Anyway, today I decide to make a few test prints following Sandy Kings process. And to check that the print was clearing OK I coated a small area away from the print and covered with a piece of dense black plastic bag (from an Ilford box).

After exposure and on removing the bag the coating was still yellow but on pouring in the developer (20% sodium citrate with citric acid and 4ml dichromate) the coated area that hadn't been exposed to UV light and was covered turned grey. Thus I assume that somewhere along the way the sensitiser has been fogged.

I'm am using old silver nitrate but it is clear and looks fine, in fact I made some salt prints recently with it and they looked ok and no evidence of fogging so I'm guessing that the ferric oxalate has become fogged? Is that possible or am I looking at another problem here?

The paper used was Arches Platine, I have since made up a fresh batch of ferric oxalate under a weak tungsten light, the solution started lime green but has also turn a very dark green/brown. The distilled water was at around 60 degrees C and it has dissolved quickly but waiting to see if it clears.

Any help would be much appreciated.

 

[Andrew O'Neill]

Why are you putting Oxalic acid in? Maybe you should try without it and see what happens.

 

[UKJohn]

Hi Andrew, the Oxalic acid is apparently, according to the instructions that came with the Ferric Oxalate, added to speed up dissolution.

 

[UKJohn]

Not being a chemist I do follow instructions pretty closely but previously when I've made up Ferric Oxalate it hasn't been suggested to use Oxalic acid. I assumed this was just an aid to dissolving the powder and wouldn't be detrimental to its effectiveness. But I take your point and mixing without is sensible. I have 5g left so can make up a very small quantity and see what happens.

 

[Andrew O'Neill]

The Ferric Oxalate I get from B&S in the US goes into solution quite nicely. Before that, I was getting FO from a source in Canada that gave me nothing but fits. Perhaps its your FO? Anyway, I'd try it without Oxalic acid. If you still get fog, it's most likely the FO.

 

[UKJohn]

Andrew, thanks for the help. I thought purchasing the FO locally was a sensible thing to do, but thinking about getting from B&S would probably have been a better and cheaper option.

 

[Andrew O'Neill]

The stuff I sourced within Canada (Toronto), was lumpy that I had to break up with a spoon before mixing in. The stuff from B&S is a fine powder. I heated up water in a glass bottle, added the FO, gave it a good shaking for a few minutes, and Bob's your uncle. The other stuff always had sediment at the bottom, and water darker.
I hope your FO works without the Oxalic acid... pity to buy something only to have it sit on the shelf.

 

[Tom Taylor]

Nicol's Kallitype II Sensitizer calls for 20 gm ferric oxalate added to 120mL of heated water and when dissolved to add 5 - 10 grains of oxalic acid to it then filter and add 8 grams of silver nitrate to the filtered solution.

Thomas

 

[nmp]

If you have some potassium ferricyanide, you can test if the FO is compromised. Free oxalic acid would react with silver nitrate to form silver oxalate precipitates

 

[UKJohn]

Hi nmp, how exactly do you use potassium ferricyanide to check if the FO is compromised? Thanks.

 

[nmp]

Hi nmp, how exactly do you use potassium ferricyanide to check if the FO is compromised? Thanks.

Check out Photo Formulary's literature, has a nice write-up about it on pages 2-3:

http://stores.photoformulary.com/content/07-0070.pdf

B&S cautions that a false positive can occur if there is EDTA in the solution:

https://www.bostick-sullivan.com/articles/ferriccoalate.html

:Niranjan.

 

[UKJohn]

That's great thanks I will give it a go.

 

[UKJohn]

Wow...isn't that a fab test, so having just tried it on two bottles of FO I made up the other day, one using Oxalic acid and one without, both turned the most beautiful prussian blue! Great but at least I have learnt something new so that's a positive. My next question is how did the FO become compromised, was it poor quality when sent or is it my working method during mixing. What sort of light should it be mixed in? Thank you.

 

[nmp]

Wow...isn't that a fab test, so having just tried it on two bottles of FO I made up the other day, one using Oxalic acid and one without, both turned the most beautiful prussian blue! Great but at least I have learnt something new so that's a positive. My next question is how did the FO become compromised, was it poor quality when sent or is it my working method during mixing. What sort of light should it be mixed in? Thank you.

I do everything in the traditional darkroom safelight, just to be sure. I have never mixed my own FO, but have a refrigerated pre-made bottle of solution from Photo Formulary (for Pt/Pd) since a few years that is still clear with only a hint of blue when ferricyanide-tested. The bottle should be dark brown, by the way, for storage. In case you are not doing that, it would be one change I recommend. If you have a clear bottle, just cover it completely with aluminum foil after using.

If you still have some solid FO, do the test by dropping a couple of crystals in a dilute ferricyanide solution. If it turns blue as well, it was probably not your mixing and handling. If it does not, then it is.

Here is an experiment you can try with the solution at hand, since you are in the learning mode. If there is ferrous oxalate in the solution, which the ferricyanide test says you do, then when you add silver nitrate to it, it too should get reduced to silver metal and precipitate out. (Incidentally, that is the source of fogging if allowed to be brushed on to paper.) Allow for the silver metal to settle down (if it does not settle, this won't work) and then use the clear solution from the top. See if that produces a clear print. I would use the solution with no oxalic acid added for this. Otherwise it will complicate thing by formation of silver oxalate precipitates as well.

:Niranjan

 

[UKJohn]

I think to be perfectly honest, I need to start a fresh so will order some more FO in a few weeks and work under safe light conditions which makes perfect sense. I do store all solutions in brown bottles so maybe it was my weak tungsten light that has caused the problem. I will give the other test ago and see what happens. Thanks very much for all your help.

 

[Andrew O'Neill]

I doubt it was your weak tungsten light. I work under a 60W with no issues. It was bad FO from the get go.

 

[UKJohn]

I received 50g of FO from Bostick and Sullivan over the weekend, made up 10g with 50ml distilled water at 21 degrees c. It cleared in around 2 hours a massive difference compared to the previous batch I bought from the UK that I couldn't get to clear. Will hopefully be able to make a few test prints later this week.

 

[Andrew O'Neill]

You mixed it in 21C water?? That's amazing!

 

[UKJohn]

Hi Andrew, it was. I have a 25 litre container of distilled water, checked the temp, it's pleasantly warm for the UK at present and my darkroom is around 21deg c. To be honest I wasn't sure whether to warm up to around 40 deg c but decided in the end to go with. I was surprised myself how quickly it dissolved and cleared.

 

[richyd]

John, a good source of chemicals is Disactics in France, may also be cheaper with import taxes than getting from the US. They have a very good article on their site describing a process to get FO into solution, it's in French but easy enough to follow. I have just started with Kallitype and although I orderd some chems from them am not setup to be able to do the ferric oxide into solution process so I bought some pre dissolved from a seller on eBay as a two part sensitizer kit. Last wek I tried a step strip and it worked great. I was a bit worried as I bought it at the end of last year.

 

[pdeeh]

Apropos Ferric oxalate,
One doesn't have to order it in from the USA, it can be got from https://www.wetplatesupplies.com in the UK.
Not cheap at £25/25g (+shipping) but probably comparable to B&S' price, and no excessive shipping delays.
I've no connection with them btw, except as a satisfied customer - quick, well-priced, friendly & helpful.

 

[UKJohn]

Hi pdeeh, I did orginally buy the FO from Wetplate Supplies (as I was looking for a UK supplier), quick delivery but found I couldn't dissolve the stuff and when tested it was fogged. Correspondence with them hasn't been great either about the issue so that's why in the end resorted to B&S. You do get twice the amount for a cheaper price and with postage and import taxes probably doesn't work out that much more expensive. It has been frustrating but I understand that the powder lasts a long long time so only made a small amount up and as I said dissolved very quickly so all seems good so far.

 

[pdeeh]

OK thanks for the feedback. I wanted some oxalate for a different process, but I'll probably put that on the back burner for the time being.
Shame that they didn't respond satisfactorily to your problem.
I think you can also get it from Moersch in Germany, but otherwise it is a bugger to source unless you want to make it yourself.