Hypo-Alum Precipitate: Filter or not?

[StephenT]

I have made up a batch of Hypo-Alum Toner using the Formulary's kit, and have used the Silver Nitrate and the Iodide additives they provided. My first time using Hypo-Alum. I was surprised by the milkiness of it, but from previous forum posts I understand that it is normal.

Today I started "seasoning" it with some prints using Ilford MGFB Classic. The toner solution contains a LARGE amount of fine, sandy-like, precipitate (I assume it is precipitate). Needless to say, I have some stuff ordered so that I can make a temperature controlled bath in which to float my toning tray. Preheating the toner to 125 in a microwave gets it up temperature in a beaker, but that temp rapidly falls off without a water bath. Thus, my last two prints are going to spend the night in the toner.

I plan to use this stuff forever replenishing with the other liter as needed (I got the 2 liter kit and split it after mixing into two one liter amber boston rounds. Thus the call for some expert advice.

It's been a long, actually VERY LONG, time since college chemistry, but would I be correct in thinking that the precipitate in my Hypo-Alum is colloidal sulfur and that I should NOT filter it out? At this time, there is hardly any odor that I can detect - is that a good thing at this point or a bad thing?

 

[Gerald C Koch]

As you note a milkiness is normal. However is you experience any particles sticking to prints then filter the solution. Colloidal sulfur is very fine and will pass through filter paper.

 

[StephenT]

Thanks Gerald. I appreciate your input and have read many of your posts on this forum. I was hoping you would see and comment on this thread.

This morning, the particulate matter has become much "finer" in form, the prints are showing signs of bleaching and toning, and the solution is beginning to develop a slight odor. I think it is beginning to "ripen."

I am going to leave the prints in solution until this evening (five 8x10's in an 11x14 tray in one liter of solution), and then bottle it up. I'll pull it out in a few days after I have the water bath "constructed," and feed it some more test prints.

For the water bath, I will be using a Rubbermaid food service bin, an aquarium pump, an immersible beverage heater, and an automatic temperature controller - total cost well less than $100. It will see service outside on my deck.

Any other suggestions/comments you or anyone else may have are most welcome. I know there are sixteen gazillion posts on toning, and I have read just about all of them at least once, but am sure I have missed some important points along the way.

Thanks again.

 

[Gerald C Koch]

The exact temperature is really not important if it is at least 120F. Toning is done by inspection rather than time. Some people use a heating pad under the tray to keep it warm.