Residual fixer removal: Diffusion times?

[baachitraka]

May I know how long it will take for the diffusion process to complete to remove the residual fixer?
- Paper size:8x10 inch
- Water temperature: 20°C
- Adox Adoxfix.
- Previously prints are treated with Sodium Carbonate solution.
- Prints are then transfered to tray of water and let it stand for 20-30mins. I hope the diffusion process takes places here.
- The above step is repeated 4-5 times.

 

[Prof_Pixel]

Without agitation, diffusion is a very slow process. Especially as you get down to low concentrations in the paper.

 

[baachitraka]

How about letting it stand over-night?

Is diffusion process reversible?

 

[Ronald Moravec]

Hand interleave, empty tray. fill & interleave stack of prints two times. Repeat 5 times for RC. 10 for fiber. This is more effective than any print washer because you start with clean water every time rather than diffusing out dirty water. 5 minutes for RC, 20 for fiber. ecological also.

 

[Photo Engineer]

Ronald, many can dispute this and Mason of Ilford has disavowed the fill and dump method in favor of continual running water. I am not going to reproduce the differential equations here again but the dump method only approaches an archival level whereas the running water method does.

In answer to the OP, no one can say for sure because of differences in water, coated materials and fixer formulation. The best method is to use a retained silver test and a retained hypo test using your conditions.

PE

 

[Gerald C Koch]

Diffusion for FB papers very slow since it is more complicated than a strictly diffusion controlled process. The thiosulfate ion is held by the paper fibers. This is why it is important to use a hypo clearing agent. The chemical in it forces the thiosulfate ion off the paper fibers. RC papers are much faster since diffusion is the only factor.

 

[baachitraka]

Yes, I would like to perform the retained silver test and retained hypo rest. Is it a DIY test? Can I do it at home?

I made 20 prints otherday, portraits of fellow students from the language school and washing them at once with continous flow of water may be challenging.

 

[Slixtiesix]

Changing times of 20-30 min are far too long. I would rather toss the water after 5 minutes and do that 8-10 times.

 

[Anon Ymous]

A DIY test for retained hypo is the HT2 test (more info in (there was a url link here which no longer exists)). You don't need to make 1l. Realistically, 50ml is more than enough for some years. I've made some and stored it in an amber bottle with a dropper. Please keep in mind that silver nitrate will stain skin, so wear gloves when preparing the solution. The solution can also leave stains, so don't splash it anywhere.

EDIT: Perhaps I should stress some things for clarification. You should check the color and density of the stain 2 minutes after applying the drop (and blotting it). It may look perfectly clear, so it passes the test, but the same spot can become stained after some time. This thing can ruin a print, so it is a good idea to have a scrap print that has been processed in the same way with the other prints.

 

[MartinP]

Is sodium carbonate effective as a washaid? I thought sodium sulfite was usually used? And with a static boundary layer of water next to the print the diffusion will not really work quickly - 'stuff' moves from a high concentration to a lower one until the concentration is equal, so the more clean water comes next to the print, the better. That might be achieved by agitating, momentary lifting and draining, emptying and refilling etc. etc.

 

[baachitraka]

After a while the Sodium Carbonate solution turned yellow but clear.

- Fix for 120seconds.
- Wash both sides.
- Into the tray of Sodium Carbonate(not mono-hydrate) solution, initially it was bit cloudy.
- After a while it has turned to yellow and clear.

* Nevertheless, I still need to find an effective way to wash many prints at once.

 

[baachitraka]

My stock of Sodium Sulfite has ran out and only got 500g of washing soda.

Any reason why color has turned to yellow from cloudy white?

 

[gone]

I had a rather odd way of washing large runs of fiber prints. If I had a lot of them to wash, which is not something I do anymore, they went into the bathtub that was filled to the brim. Then they were carefully swished around a bit (carefully, and I wouldn't do more than 10-15 to make it manageable). After 15-20 minutes the tub was drained, the prints were transferred to a deep tray w/ fresh water, and I put the prints back into a half filled tub w/ the drain plug cocked to allow slow drainage. Then I turned on the faucet and kept a flow of water in and out of the tub. Something, anything, was placed in the tub to keep the prints from floating under the running water. Tennis rackets worked well, and allowed some water flow. Every 20 minutes or so I would go back to swish the prints, drain the tub, run it back up to half filled, and then go back to my book or movie.

This went on for a couple of hours at least. Yes, it was a PITA, but I feel the large volume of water in the initial soak along w/ the mild agitation got a lot of fixer out. When they went into the large tray to soak that got a little more, and the 2-3 hour process in the tub w/ running and changed out water did the rest. We live in Florida and there's plenty of water (too much at times), so using up a lot is of no concern. It was different in the Southwest, and I had a DIY print washer then made from a big aquarium tank, glued plexi, and a pump. No matter how you do this, a pre soak in hypo is a good idea