Kodak Rapid Selenium - Capacity?

[Smudger]

The conventional wisdom is that RST is exhausted when its ability to tone slows to zero.
But,if you are using weaker dilutions (in my case, 1:15),purely for its protective effects, how can you tell when it has run out of steam?
For example, how many 8x10's would you expect from 1 US quart/0.95 litres of working solution?

 

[Oren Grad]

It's not clear how protective so-called "light" selenium toning actually is, and whether it's worth the trouble if you don't otherwise want the effects on print appearance. See the following; although it's specifically about tests with microfilm, which is perhaps more vulnerable, if you read it carefully the logic and the caveats apply more broadly:

http://cool-palimpsest.stanford.edu/byorg/abbey/an/an12/an12-5/an12-507.html

 

[Oren Grad]

More info here, in a post I made to the LFF a while back:

http://www.largeformatphotography.info/forum/showthread.php?t=13859

 

[Rich Ullsmith]

Nice to have a few test strips lying about that you know will gobble selenium: Foma WT,for instance. If you think the solution is near the end, heat it up and try the WT test strip, or half of it rather. If that doesn't shift, then you are pretty much done.

If it gets close to that point, I like to throw in a bunch of give-away prints that are untoned.