H2SO4 question

[dancqu]

... in more or less neutral environments Sodium bisulfite
dissasociates into Na+, H3O+, SO4-- and HSO4-.

Not to leave out the SO4--. And not so very very little as
you were thinking. There are likely some who avoid the
use of sulfuric acid for more than one reason. I'm sure
there must be others than Patrick Dignan who suggest
or specify the use of bisulfate.

There are equivalence tables for many chemicals and
and chemical hydrates. Lacking is a same table dealing
with sulfuric acid and it's bisulfate. Dan

 

[AshenLight]

Hi all,

Hope you all had a great holiday! I managed to make the developer without any injury or property damage although I haven't been able to try it yet. PE mentioned that the formula sounded strange... concentrated acid to the alkaline developer. This, unless there is an error in the recipe I found, is supposedly the formula for Defender 15-D. As described it is:

Solution A
Water @ 52C 500ml
Hydroquinone 45g
Sodium sulfite (desiccated) 30g
Sulfuric acid (concentrated) 4 ml
Cold water to make 1L

Solution B
Water at 52C 500ml
Sodium carbonate (desiccated) 30g
Potassium carbonate 90g
Potassium bromide 8.3g
Sodium sulfite (desiccated) 90g
Cold water to make 1L

Mix 1:1 for use

Ash

 

[Photo Engineer]

Ash;

You are essentially making a solution of Sulfur Dioxide gas out of part A above. This is a powerful preservative for the HQ.. Note that there is more in part B. Mixing A+B will cause some foaming but not as much as making an A+B to start with. Please be careful when making part A due to the possible heat, splashing, and release of a toxic gas (SO2).

Part A and B before mixing should have very long lives and should supply a D-76 type developer with high sulfite, but no Metol. That is the basic difference between the two. Well, that and the bromide!

Have fun.

PE

 

[AshenLight]

Hi PE,

Fortunately, I have a pretty effective ventilation system on the wet side of the darkroom. Even still there was a hint of "rotten egg" in the air. I left the extractor fan on and left the darkroom for about 15 minutes until the odor cleared. There was a bit of an exothermic reaction mixing part A but it seemed less pronounced than when mixing sodium hydroxide in cold water.

In retrospect, it seems that Kodak D-85 may be a better formula as far as Lith developers go. I suppose acetone can be substituted for the paraformaldehyde although I need to find a ratio for the substitution.

Ash