• Welcome to Photrio!
    Registration is fast and free. Join today to unlock search, see fewer ads, and access all forum features.
    Click here to sign up

Fixing salt prints: why two trays?

CreationBear

Subscriber
Allowing Ads
Joined
Jan 29, 2020
Messages
125
Location
Knoxville, Tennessee
Format
Large Format
I’ve been happily re-reading Christina Anderson‘s book on salt printing lately, but one small detail left me confused: she recommends using two trays, presumably of the same dilution of fixer, during the printing process, That would make sense to me if fixer were “one shot,” say, like some gold toners, but it doesn’t seem to be the case that she means a tray of chemistry is exhausted by a single print.

Anyone able to help my confusion?
 

fgorga

Member
Joined
Aug 31, 2015
Messages
858
Location
New Hampshire
Format
Multi Format
It is all about serial dilution...

This is probably easiest to explain with some concrete but not real numbers.

Let's assume that your print contains 100 mg of silver ions that needs to be removed. We will also that you let prints soak in fixer a tray of fixer long enough to remove 90% of the silver ions from your print.

With one tray of fixer, you can remove 90% of your 100 units of silver. Thereby leaving 10 units of silver ions in the print.

If you now transfer that print to a second tray, you can remove another 90% of the remaining 10 mg of silver, leaving you with 1 mg silver in your print.

Again, the numbers in my example are not real. This however, does not affect the conclusion: that two trays of fixer are much more effective in reducing the residual silver than a single tray.
 

MattKing

Moderator
Moderator
Joined
Apr 24, 2005
Messages
55,431
Location
Delta, BC Canada
Format
Medium Format
Can you employ a single tray process instead?
By that I mean fill tray from first fixer container, at end of first stage empty into 1st fixer container, fill tray from second fixer container, at end of second stage empty that into second fixer container.
 
OP
OP

CreationBear

Subscriber
Allowing Ads
Joined
Jan 29, 2020
Messages
125
Location
Knoxville, Tennessee
Format
Large Format
Thanks Matt, that might work as well, though my "Harry Potter" dim room (a small vestibule at the top of the attic stairs) has me trundling a utility cart to the guest bathroom to get/drain water.. Definitely a lot of towels on the floor!
 

MattKing

Moderator
Moderator
Joined
Apr 24, 2005
Messages
55,431
Location
Delta, BC Canada
Format
Medium Format
Underbed trays as movable "sinks" are the temporary darkroom user's friend...
 
OP
OP

CreationBear

Subscriber
Allowing Ads
Joined
Jan 29, 2020
Messages
125
Location
Knoxville, Tennessee
Format
Large Format
MattKing said:
Underbed trays as movable "sinks" are the temporary darkroom user's friend...
Click to expand...
A great point, I've been looking to get a couple of basins like they sell at big box stores to put under clothes washers as a bit of security. Otherwise, schlepping 20L jerry cans up the stairs adds a bit of cardio to the procedure...
 

MattKing

Moderator
Moderator
Joined
Apr 24, 2005
Messages
55,431
Location
Delta, BC Canada
Format
Medium Format
Four bottles that are 5L size are far easier to handle than one 20 L jerry can - and the damage potential from spilling one is much more reasonable .
Admittedly, I've been able to make temporary use of bathrooms for the last several years, but like so many here, I've got lots of practice making the non-ideal work.
 

NedL

Subscriber
Allowing Ads
Joined
Aug 23, 2012
Messages
3,430
Location
Sonoma County, California
Format
Multi Format

That's what I do. I don't reuse hypo though... I just make enough ( around 100ml ) for each stage. Hypo is cheap compared to paper and silver and toner and my time, and it's always fresh.
 

Cor

Member
Joined
Aug 21, 2006
Messages
223
Location
Leiden, The
Format
Multi Format
What I do for Kallitype: use 50 ml for a 8*10 (used once) in a flat bottom tray for 2 minutes cont. moving around the hypo, discard, and add 50 ml fresh hypo, again for 2 minutes and keep that solution for the next print and so on. This might seem very minimal but I checked it with fixer strips and there is a little bit of silver in the twice used solution and no detectable silver (with the Tetenal strips; https://www.fotoimpex.com/chemistry/tetenal-fixing-bath-tester-100-stripes.html) in the first solution. I do think that you get rid of the unexposed silver in the many wash, clear, rinse and toning steps before the hypo step.

Best,

Cor
 

Raghu Kuvempunagar

Member
Allowing Ads
Joined
Jul 28, 2016
Messages
3,140
Location
India
Format
Multi Format
Cor said:
I do think that you get rid of the unexposed silver in the many wash, clear, rinse and toning steps before the hypo step.
Click to expand...

I would expect most of Silver Nitrate and Silver Oxalate to be complexed and removed in the development (Sodium Citrate) and clearing (Citric Acid) steps if these steps are sufficiently long.

Would be interesting if the unfixed print can be Sulfide toned right after clearing. If there is any residual non-image silver in the print after clearing, Sulfide toning would show some fog.

Interestingly, even old books recommend fixing in dilute hypo solution, perhaps to be foolproof as some printers might use tap water instead of distilled water in the developer and clearing bath.
 

nmp

Member
Allowing Ads
Joined
Jan 20, 2005
Messages
2,101
Location
Maryland USA
Format
35mm

Not all of the silver salts come out - most will form collodal salts with various anions in the wash/developer and be carried away (the milky stuff.) But some portion will precipitate out and stay in the paper. It is this remaining silver salts that require the fixer to remove. If you tone with sulfide or selenium prior to fixing, you will get staining. Come to think of it, if you don't get staining, you won't require fixing. The reason selenium or sulfide toners are also used to test for residual silver or adequate fixing.

Gold toning does not touch silver salts, only silver metal (or silver nitrate if it is still around for any reason - hence the reason to use NaCl bath in salt prints to make sure) so it is safe to do before fixing.

:Niranjan.
 

Raghu Kuvempunagar

Member
Allowing Ads
Joined
Jul 28, 2016
Messages
3,140
Location
India
Format
Multi Format

That's the idea. Sulphide toning will make it clear if all non-image silver was removed by development and clearing steps as seem to be suggested by Cor's tests using Tetenal fixing tester stripes.

​

 
You must log in or register to reply here.
Menu
Log in
Register