Chemistry Gurus help.

Bob Carnie · Mar 8, 2020

I had some help years ago with a problem with scum marks on my fibre prints after washing.

I think I was advised to use a concoction of Sodium Hexametaphosphate and water as a pre rinse, Does this ring a bell to anyone and do you have a mixture of this grams to litre of water I could use.

I am getting old and forgetful, I should have made my charts on this

thanks in advance

Bob

Ian Grant · Mar 8, 2020

You were getting this after using plain Sodium Sulphite solution as a wash aid I remember, and advised to add Sodium Hexametaphosphate to the Sulphite solution.

I live in a very hard water area and never get an issues but I always remove all the water from the front of my prints by wiping with kitchen towelling. I only use FB papers and a plain Sulphite wash aid.

Ian

Tom Kershaw · Mar 8, 2020

I'm in a very hard water area and have suffered this problem on occasion. However more recently I've not had any issues.

larfe · Mar 8, 2020

Not a guru of any means but yes it has to call for sodium hexametaphosphate along with the sulfite and the only formula was in the book of Ralph Lambret

Failing that, a bath of acetic acid will remove the scum marks easy

Bob Carnie · Mar 8, 2020

larfe said:
Not a guru of any means but yes it has to call for sodium hexametaphosphate along with the sulfite and the only formula was in the book of Ralph Lambret

Failing that, a bath of acetic acid will remove the scum marks easy

Would Citric Acid remove the scum as would acetic acid .. and if so how many grams per litre of water.

Ian Grant said:
You were getting this after using plain Sodium Sulphite solution as a wash aid I remember, and advised to add Sodium Hexametaphosphate to the Sulphite solution.

I live in a very hard water area and never get an issues but I always remove all the water from the front of my prints by wiping with kitchen towelling. I only use FB papers and a plain Sulphite wash aid.

Ian

Would you be so kind to remind me how many grams of the Sodium Hexametophosphate to litre of water you would suggest... thanks a bunch Ian

Anon Ymous · Mar 8, 2020

Yes, sodium hexametaphosphate should be added to the water for the sulfite bath before adding sulfite. 2g/l is more than enough and accuracy isn't critical. If EDTA-4Na is easier to obtain, then it can also be used instead, 1g/l.

Ian Grant · Mar 8, 2020

Anon Ymous said:
Yes, sodium hexametaphosphate should be added to the water for the sulfite bath before adding sulfite. 2g/l is more than enough and accuracy isn't critical. If EDTA-4Na is easier to obtain, then it can also be used instead, 1g/l.

That's the ball park figures, they aren't to critical,

Ian

Doremus Scudder · Mar 8, 2020

Bob,

Here are a couple of wash-aid recipes with sod. hexametaphosphate/EDTA: Maybe they'll help. The first is from Ralph Lambrecht, which he made available here, so I'm sure he won't mind my re-posting it.

Hypo-Clearing Agent (HCA-1)
water (52°C/125°F)....................750 ml
sodium sulfite (anhydrous)..........100 g
sodium hexametaphosphate*.......5 g
cold water to make.....................1l
From Ralph Lambrecht. Dilute 1+4 for film or paper
* Add with hard water supplies to prevent calcium scum. Depending on your water hardness, you may want to add up to 1g/l of sodium hexametaphosphate (Calgon) after the sodium sulfite has dissolved. Otherwise you end up with calcium deposits on the print. Note that this formula omits the sodium bisulfite. It can be mixed one-shot as well by adjusting amounts.

"Kodak HCA" substitute (stock solution)
Water .......................................500 ml
Sodium Sulfite (anhydrous)..........100 g
Sodium Bisulfite..........................1.25 g
EDTA Terasodium Salt..................2 g (up to 5g)
Sodium Citrate (5,5-hydrate) .........5 g
Water to make ............................1 liter
This may very well be Kodak's formula. Dilute 1:4 for use. The EDTA and citrate are for hard water sequestering.

If the scum on your prints is calcium, an acetic acid stop may dissolve it off. Citric acid may work too, you'll have to give it a try. And you may have to mix a bit stronger than regular stop for it to work quickly. A couple quick tests should tell the tale.

Best,

Doremus

Rudeofus · Mar 9, 2020

The advantage of Acetic Acid over Citric Acid is, that Acetic Acid will evaporate if left in the print. If you wash your print again after scum removal, then there should not be much of a difference between these two.

larfe · Mar 9, 2020

Rudeofus said:
The advantage of Acetic Acid over Citric Acid is, that Acetic Acid will evaporate if left in the print. If you wash your print again after scum removal, then there should not be much of a difference between these two.

Am I misunderstanding or what you are saying is that the prints need no washing after acetic? This wouldn't apply to vinegar would it?

koraks · Mar 9, 2020

larfe said:
Am I misunderstanding or what you are saying is that the prints need no washing after acetic?

That's not what he said. His statement only applies to the acetic acid itself, not the remnants of fixer and silver compounds left in the paper after fixing.
However, I have my doubts about the statement itself. It implies that acetic acid would sublime, which is not likely to happen IMO to a significant extent.

This wouldn't apply to vinegar would it?

Vinegar is simply acetic acid diluted with water. With, of course, additional impurities depending on the type and kind of vinegar used. E.g. cleaning vinegar will likely have some, but minimal impurities that may or may not influence print permanence.

138S · Mar 9, 2020

Bob Carnie said:
prints after washing.

Toronto Waterloo area (IIRC) water is extremly hard there at 400mg/L. An smart solution is a ($150) reversal osmosis device for final rinses.

I guess that not many make that kind of final rinse, and perhaps it's not necessary, I do it as my Tap water is salty and it's straight to do, water of that final rinse can be reused.

If you weight your print wet and dried, then you may apply your tap water salt content and you'll know how much salt you leave in the paper, IMO better if the print the print contains no salt from that source. If there are marks on the surface then salt is left inside

Max Thiosulphate content is 0.050gr/m2 for LE100 and 0.015gr/m2 for LE500, we can caculate if the (Tap water) salts we leave in the paper are in those ranges.

Bob Carnie · Mar 9, 2020

Thank you all, this is why I am constantly still coming to Photrio , its been 16 years now for me and I still am learning here.

Rudeofus · Mar 9, 2020

koraks said:
That's not what he said. His statement only applies to the acetic acid itself, not the remnants of fixer and silver compounds left in the paper after fixing.
However, I have my doubts about the statement itself. It implies that acetic acid would sublime, which is not likely to happen IMO to a significant extent.

Pure Acetic Acid is a liquid with a boiling point just above water. If the acetic acid rinse is sufficiently pure, and I am quite sure that Bob can find pure Acetic Acid, then it will evaporate without residue. We frequently use it to clean mirrors in our bathroom.

The idea behind my suggestion was as follows: you immerse paper with scum in acetic acid, the acetic acid dissolved the scum and runs off. The remaining acetic acid and water will evaporate. You can not do this with Citric Acid or Boric Acid.

koraks · Mar 9, 2020

Don't you think some of the acetic acid remains with the remnant of moisture in the paper, leaving the paper in an acidified state?
Another question is if that would pose a threat to image stability in the long term, which I don't know.
In any case, a subsequent wash after the acidified sulfite bath would of course wash out the acid as well (any acid, also citric or boric) and thus, the argument is somewhat hypothetical for any workflow aimed at decent permanence.

Bob Carnie · Mar 9, 2020

I just washed a couple of prints in Citric Acid bath followed by a wash,, and I washed some in a Sodium Hexametaphosphte bath followed by a wash, they are on the screens now drying I will see how it goes..

peterlat · Mar 9, 2020

I had the same problem a couple of years ago with my fiber prints. Here's the process that now works for me:

After the final wash I soak each print in a tray with distilled water and Ilfotol wetting agent. (Ilfotol's highly concentrated, i.e., use at 1:200.) Then, before I squeegee, I take a clean sponge, dip it in the tray to collect some of the solution, and go over the entire print surface for 10-15 sec. Then I squeegee normally, dry the prints face down, and they're fine.

Bob Carnie · Mar 9, 2020

Both methods cleared the scum nicely .. thankyou all.

Chemistry Gurus help.

Bob Carnie

Ian Grant

Tom Kershaw

larfe

Bob Carnie

Anon Ymous

Ian Grant

Doremus Scudder

Rudeofus

larfe

koraks

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138S

Bob Carnie

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koraks

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Bob Carnie

peterlat

Bob Carnie

Chemistry Gurus help.

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