Print reducer

[Curt]

I'm looking for a print reducer to clear the highlights on fiber prints, for those who do this are you making it or buying it made? This formula calls for Thiourea which is available from the Photographers Formula and sounds quite nasty but is simple. Ansel Adams has a formulation in the 'Print' book and he uses more chemicals than this simple one.



Non-Staining Print Reducer
To clear highlights in prints


Solution A

Water............................500 ml
Thiourea...........................15 g
Sodium Thiosulphate (Hypo)700 g
Water to make.....................1 L

Solution B
Water...........................200 ml
Potassium Ferricyanide........75 g
Water to make...............250 ml

 

[Doremus Scudder]

There are other alternatives to thiourea reducers for your purpose.

A more common ferricyanide bleach is what I use for clearing whites in prints. There are several combinations you might try first.

The simplest is a weak ferricyanide solution (0.1-1.0% working solution). Give the print 30 seconds in this solution with agitation, then transfer it to a tray of fixer. Sodium thiosulfate fixer works less aggressively than ammonium thiosulfate rapid fixers, but both can be used. With this method, the reduction does not take place till the print has been in the fixer for a while. Repeat the cycle as needed to reach the desired density. Note that your ferri solution will only last 15 minutes or so once you have introduced some hypo into it by returning a print to the bleach solution.

Another way is just to use Farmers' Reducer, which is a mixture of ferricyanide and sodium thiosulfate (similar to the above, but in one solution). Recipes for this are easy to find. Dilute as needed to keep it from working to fast. Again, the working solution life is short.

My favorite method lately is to use a rehalogenating bleach of ferri and potassium bromide. I keep stock solutions of 10% ferricyanide and 3.5% bromide. These can be mixed in a 1+1+whatever to get the strength you need. (i.e., many dilutions possible). With this method, the bleaching happens in the bleach tray as the silver is converted to silver bromide. Pull the print before desired density has been reached and rinse it well for several minutes in running water. The print can be returned to the bleach solution if needed at this point. After desired density has been reached, fix the print completely and wash as usual. The life of this solution is significantly longer.

Note that this method can change how prints tone, so keep that in mind when planning toning.

Hope this helps,

Doremus Scudder

 

[nworth]

A simple Farmer's reducer will work for prints. I'm sure Adams had his reasons for using the thiourea formula, but the simpler solution also works.

Farmer's reducer for prints
Stock Solution A
Potassium ferricyanide 64 g
Potassium bromide 30 g
WTM 250 ml
Stock Soultion B
Sodium thiosulfate 120 g
WTM 500 ml
For overall reduction, use 7.5 ml of Solution A, 180 ml of Solution B, and 1500 ml of water. Increas the amount of Solution A to speed up reduction.
For local reduction, use the same proportions as for overall reduction.
For spot reduction mix one part Solution A with 2 parts Solution B. Use undiluted.

 

[Curt]

Kodak covers several formulas and methods in their publication O-10 which is only available from them by fax or mail. I had them send me a copy and I scanned it to a PDF.

Kodak's R-4a formula doesn't have Potassium Bromide in Solution A What does Potassium Bromide contribute to the chemical mix.

The R-4a is about as basic as it gets. Stephen Anchell has a Framer's reducer with Potassium Ferricyanide and Potassium bromide as Stock Solution A and Hypo for Stock Solution B and says Solution A will last at least 6 months in a glass brown or green bottle.

The Anchell formula is the same as nworth gave in the first post.

Thank you both for helping me nail down this, I used to use Farmer's reducer but that was way back and I had forgotten what I did. It's coming back now.

Curt

 

[CBG]

Potassium Bromide in a ferricyanide bleach does something very useful to the action of the bleach. It returns the exposed and developed silver image back to a light sensitive state by adding a halogen back onto the silver as long as you don't refix that area. Such bleaches are called rehalogenating bleaches.

Lets say you over-bleach an area. If you used a rehalogenating bleach (and if you have not refixed the image after the overbleaching) a little too long, just rinse off the print to get rid of the yellow color of the ferricyanide, and then pop the print back into your print developer. You can do this in room light. The bleached image will come back, and then you can try again. You can actually repeat this multiple times. It's pretty cool, since it is terribly easy to over-bleach.

If you use farmer's reducer, you only get one chance since it removes the silver as it bleaches. It has fixer built into it.

I'd rather have the rehalogenating bleach and the ability to redo the process.