Quick Question... Citric acid from the grocery store; ok for photography?

[holmburgers]

The stuff that they sell for home canning (Mrs. Wages) says it contains less than 2% Silicone Dioxide for "anti caking".

Would this pose any problems for its use in photography? Heck, for all I know the stuff from PF has the same thing in it, but just want to make sure.

Thanks!

 

[greybeard]

From a chemical standpoint, the silica will be essentially inert, but it is in the form of a very fine powder which will be rather difficult to completely remove. (That's silicon dioxide, by the way; the other stuff is for enhanced development of Hollywood starlets, not film ) If you are making 8x10 contact prints, it won't matter; if you are working with Minox film, it will. In between, settling the solution and filtering before use may be adequate, even if it doesn't get out the colloidal particles.

Since citric acid is cheap and mailable, it might be better to just go with a non-household product from PF or some other supplier.

 

[bdial]

You can use Kosher sour salt which (so far as I know) has no silica in it. There are some threads in here about mixing it for stop bath.

 

[holmburgers]

Thanks for the heads up on silicon vs. silicone.

To be honest, I'm not sure even what process I have in mind at the moment, but I know it's a widely used substance so I was hoping this was a "drop in" replacement if the need ever arised.

However, before using it in a critical situation I'll get the real deal.

Thanks!

 

[Gerald C Koch]

The silicon dioxide is insoluble in water but may stick to film and print emulsions.

I buy citric acid, ascorbic acid and sodium erythorbate (isoascorbate) from www.suttonsbayspices.com, look under sausage supplies. Citric acid is also available from www.thechemistrystore.com and www.techcheminc.com.

 

[zenrhino]

Since I see you're out in Lawrence, stop by Bacchus & Barleycorn (or Homebrew Pro, et al) and see if they have liquid citric acid in stock.

 

[holmburgers]

Ahh, this is used in homebrewing as well? That's a boon... my roommate brews his own beer! I'll see what he's got. Thanks for the tip!

And actually I've been to Bacchus & Barleycorn, last year on christmas eve in a blizzard for a list minute gift. My first truly white Christmas... pretty cool. FWIW