van dyke sensitizer settling

[matthew001]

I mixed up a bunch of vds about 3 months ago, I have stepped away for the process for a while and just came back to it last night. I noticed a 1/8" layer of material at the bottle of my jar. I'm having trouble getting it all back into solution. I've tried warm water, stirring, shaking. Is this what is referred to as 'precipitate,' in which case I could use a few grams of tartaric acid to aid in dissolving. Any suggestions?

 

[cliveh]

When you make up your Van Dyke brown solution, take care when adding the silver nitrate solution, as this should be added very slowly, a drop at a time and stir continuously.

 

[Herzeleid]

Adding a few grams (do it 1 gr increments) helps solve the precipitate, not entirely but to some extent. I believe it lowers DMax, max dark tones get lighter if you put too much TA. At least it did for me.

Don't mind the precipitate if it does not effect your image. You should shake the bottle, let it sit for a moment, use a syringe to get from the top of the liquid. This way, you should have the least amount of precipitate onto the paper.

Even adding drop by drop silver nitrate into the solution, I still have precipitate, some posts points it at the purity of FAC.

I am looking for a solution to that myself, without effecting the dark tones.

 

[Jim Noel]

let the precipitate settle and decant the VDB. it will work fine.

 

[matthew001]

thanks for the suggestions. I printed with it last night, seemed to be OK. Just seemed like a lot at the bottom. I use a dropper to apply the sensitizer so I always take from the top. I wasn't sure if it would separate in which I would be taking up mostly water.

 

[Gadfly_71]

What Jim said. I usually decant it using a funnel and a coffee filter (very slowly, and very carefully).