Re: Shell Life of Van Dyke Sensitizer

[Sam Wang <stwang@clemson.edu>]

Sandy,

If all you want is a brown image, then the stock solution keeps indefinitely.

However, if you want maximum D-Max, obviously you aren't going to get 
it from a solution with half of the silver attaching itself to the 
bottle. THE way to keep it, then, is to keep the tree parts separate 
and mix them together just before use, or shortly before use. How 
short? I'm not sure, but I would say within a day or so.

By the way, the silver nitrate is the last solution to add to the 
mix, and it should be added a few drops at a time, with vigorous 
agitation. Otherwise it will not go into solution and show up as 
milkiness. If you THEN add more tartaric acid, it will go into 
solution but speed will suffer.

In separate bottles they keep for at least months with no problem.

But, Sandy, I thought you hated Vandyke?

Sam

>Hi folks,
>
>This morning I pulled out an old bottle of Brown Dyke Sensitizer, 
>mixed about a year ago, that had been left for many months with a 
>small quantity of sensitizer in the bottom, to a depth of about 
>3/4". What I found was a perfectly beautufly coating of silver 
>plating on the inside of the bottle (but very shiny when views from 
>the outside through the amber colored plastic). Given the fact that 
>the silver has left the solution and formed a nice plating on the 
>side of the bottle makes it pretty obvious that the shelf life of 
>this particular bottle was quite a bit less than a year.
>
>Which brings me to this question. What is the effective shell life 
>of Van Dyke sensitizer, assuming that it is kept in a brown, tightly 
>capped bottle, and stored at room temperature in the dark, or in 
>very subdued light?
>
>Any comments about this, or other specific information about storing 
>this sensitizer, appreciated.
>
>Sandy King