Acidification of Fabriano Artistico for Pt/Pd

An excerpt from my workshop manual:

To make potassium oxalate from raw materials:

(You may want to do this outside or at least with good ventilation as the process gives off CO2, some heat and a significant amount of bubbles.)

To make 2 Liters:

1. Start with 1100 ml cold distilled water in a large container

2. Add 450 grams of Potassium Carbonate mono with stirring until dissolved. This will cause the solution to heat up.

3. SLOWLY add 400 gm of oxalic acid to the potassium carbonate solution with stirring, waiting each time you add the acid until bubbling stops. Continue until all of the oxalic acid has been added.

4. Add water to bring total volume to 2 liters. Check the pH at this point. It should be near 7.0 (neutral). Now add more oxalic acid in small amounts and keep checking the pH. When you get the pH to about 6.0, you’re done.

The pH of potassium oxalate is important. It should be used in an acidic state. This should be checked periodically with a pH meter or narrow-range pH paper. If the pH rises above 7.0 (i.e. alkaline) it can be adjusted by the addition of small amounts of oxalic acid. Add the oxalic acid powder a little at a time and keep rechecking the pH. I usually add oxalic until the pH reaches about 6.0. Filter your developer once in while and maintain the pH and you can use it for a very, very long time.

Great tip. Thanks a lot.

Kerik...

Have you used the currently available Fabriano Traditional White for anything?

Hi Kerik,

Diluted (non-fuming / safer than concentrated -> I don't advocate using or storing concentrated HCl at all! No need to buy concentrated form. I don't get why concentrated comes into your mind in the first place?) muriatic acid is as close as the nearest Home Depot (pool or garden sections) to ordinary US citizens (it's sold in any supermarket in Turkey for cleaning / "dissolving" calcium residue in the bathrooms and kitchen where the tap water is hard - does that ring bells? Calcium residue -> calcium buffer...) and would be definitely cheaper than buying oxalic acid from a chemicals supplier. No need pure grade; so called technical grade is OK. Also, a little goes a long time since it's further diluted (to final concentration of 1% to 5%). But I'm not in pennies and cents here...

To me diluted (to safe levels) liquid acid is much safer than and easier to weight/operate compared to any powder. Powder can get airborne (and small particles can shed most easily), liquid does not.

Grittiness is a fact to me since I've experienced this more than once, with more than one paper (all when coating with a glass rod). In any case I still think (and will tell people) that HCl or acetic acid (white vinegar) is definitely a better ("right") method for the purpose. My END.

Philosophy of my objection: I don't like the idea of "if the best do it, it's OK for me too" kind line of thought, especially in the "alt" context. It would be better for the novice/less experienced practitioner to provide firm grounds to themselves why they are doing something in a particular way.

Of course it's certainly understandable to prefer (and suggest) oxalic when one stocks and use it for other purposes too, moreso if they aren't experiencing any negative effects.

Now, this sound like the infinite (and useless) discussion (somewhere else) about glyoxal against formalin against gluteraldehyde (in the context of hardening gelatin sizing)...

BTW, I must add that I'm not questioning / discrediting anyone's (including yours) mastery, technical competence and technical / artistic talent here. I deeply admire your pt/pd and gumover pt/pd work and always drive my students to your website for a perfect demonstration of mastery... So don't take it personal.

Regards,
Loris.

Kerik said:

Here in the states oxalic acid is cheap and easy to get. I never get any discernible residue or gritty surface with my method (soaking, not brushing on). I'd rather have a safer powdered form of acid in my darkroom than a bottle of liquid HCl. I buy oxalic acid in relatively large quantities because I also use it to make potassium oxalate developer for a fraction the cost of buying potassium oxalate. Cheap, safe, effective, NO grittiness. The end.

Click to expand...

Loris,

I agree we are approaching the infinite and useless level of discussion, but I have one last shot from my end. Muriatic acid from the hardware store is usually about 37% dilution. I don't consider that dilute and I don't want it in my darkroom. I speak from experience that it is more hazardous to use and store than oxalic acid. Being a liquid, HCl is all to easy to spill and the airborne vapors from an HCl spill dwarf the hazard from oxalic acid powder in my opinion.

You said: "I don't like the idea of "if the best do it, it's OK for me too" kind line of thought,"

Ummmm, me either!! Did I say I was "the best" or do things the way "the best" do? I'm just passing on my experiences having printed pt/pd for nearly 20 years now.

I haven't coated pt/pd with a glass rod since I found the Richeson 9010 brushes many years ago.

I'm not taking this personally and I appreciate your kind words about my work. Like you, I am just presenting my thoughts on the "right" way to do this.

PVia said:

Kerik...

Have you used the currently available Fabriano Traditional White for anything?

Click to expand...

I've used it a couple times for pt/pd/gum (but not recently). I'm not fond of the color. I much prefer the Extra White version.

PVia,

The paper appears to be fine. I've used this paper for intaglio printing where the paper was soaked for even longer. Probably a 30 minute soaking would suffice as long as it is evenly soaked.

I like the colour of the print in the 1% solution bath. Cool with a hint of warmth. If I want a cooler tone, I'll soak the paper in a 5% solution.

AFAIK, concentration muriatic acid from hardware stores is something around 30-32%. 37% is "concentrated/saturated" HCl solution. In any case, both will fume. But there are enough diluted HCl products around -> calcium remover, toilet bowl cleaner and such (usually around 10%). I'm talking about these kinds of products not concentrated/fuming HCl... I totally agree with you about concentrated HCl. Why you insist that I'm suggesting concentrated whereas I clearly stated "diluted/non-fuming" before, I don't understand.

Anyway, acetic acid (or white vinegar) also can be used. (As I also said before...) Enigmatically, I had no comments about acetic acid but only about concentrated HCl - which I haven't suggested at all...

Could be that the practical consequences of using oxalic or HCl/acetic seems to be the same (which wasn't the case for me) but I still think diluted HCl or acetic acid is the way.

Oxalic acid will definitely leave neutralization products in the paper which may or may not affect results in the short term. (On the contrary I remember someone talking about the different results they were getting depending on oxalic acid strength; colder/warmer results when everything is the same in the rest of the process...) In any case, with pt/pd printing it's better to have a purer surface (= a surface with no alien content) to print on - instead of having paper that incorporates useless neutralization remains "which we know nothing about their future influence on the print's health". And that's a very good point to me since someone doing pt/pd is surely interested / concerned about the future of their prints...

Regards,
Loris.

Kerik said:

Loris,

I agree we are approaching the infinite and useless level of discussion, but I have one last shot from my end. Muriatic acid from the hardware store is usually about 37% dilution. I don't consider that dilute and I don't want it in my darkroom. I speak from experience that it is more hazardous to use and store than oxalic acid. Being a liquid, HCl is all to easy to spill and the airborne vapors from an HCl spill dwarf the hazard from oxalic acid powder in my opinion.

You said: "I don't like the idea of "if the best do it, it's OK for me too" kind line of thought,"

Ummmm, me either!! Did I say I was "the best" or do things the way "the best" do? I'm just passing on my experiences having printed pt/pd for nearly 20 years now.

I haven't coated pt/pd with a glass rod since I found the Richeson 9010 brushes many years ago.

I'm not taking this personally and I appreciate your kind words about my work. Like you, I am just presenting my thoughts on the "right" way to do this.

Click to expand...

FWIW on cost; A 7lb pail of Oxalic is ~$22 here. A case of 12 bottles of 10% HCL toilet bowl cleaner is ~$40. The oxalic makes ~16 gallons of a 5% solution the toilet bowl cleaner 6 gallons. The toilet bowl cleaner is ~5 times as expensive.

Loris,
actually I am interested in acetic acid. I happen to have an old 80% solution which I used as a stop bath for silver (before I quit using it for its awful smell). How low do you think I have to dilute that, and how long can I leave a Fabriano sheet in it?

gm

Hi gm,

I use 5% strength (v/v) of 35% HCl (makes something like ~0.57M concentration if I'm not mistaking) for 4 minutes (agitating constantly and changing side facing the solution halfway), this is perfectly enough for printing good cyanotypes. (Which is a process that is very vulnerable to presence of alkali.) The bubbling and fizzing stops completely at about 3:30 or so. If you double the strenght (10% v/v) then 2 minutes processing is enough (tested), I just use a milder concentration to be more gentle to the paper, even if I haven't noticed any (short-term) adverse effect of using the stronger variant. 2 litres of the above solutions are enough to process an area equivalent to 5 full sheets of 22x30" sized paper (maybe more, but I haven't processed larger batches), it doesn't seem to slow down and loose strenght when used up to the previously stated capacity.

You can try to mix an acetic acid solution with a concentration something like ~0.6M to 1M and try several processing times (1, 2, 4 minutes and such). A good indication of enough processing would be the extinction of bubbling and fizzing...

5% HCl (v/v, 35% stock) doesn't smell offensive and is pretty safe to handle. (Half the strenght of the acid in our stomachs!)

Regards,
Loris.

gattu marrudu said:

Loris,
actually I am interested in acetic acid. I happen to have an old 80% solution which I used as a stop bath for silver (before I quit using it for its awful smell). How low do you think I have to dilute that, and how long can I leave a Fabriano sheet in it?

gm

Click to expand...

Thanks a lot!
gm

Don't forget to thoroughly rinse/wash processed paper. You don't want acid in the paper for the subsequent stages...

A side note about HCl (not acetic acid) and pt/pd printing is that you also get rid of small metallic remains in the paper (causing black spots and streaks in the print), since being corrosive it will dissolve those too... A bonus!