BAKING SODA: B&W film and paper developer PH

[david_lyga]

<p>Banking soda (sodium bicarbonate) is a very useful item for the B&W darkroom as it can be used to slow down development (ie, as an extreme case, for using Dektol to dev high contrast 'Process' films for continuous tone). Added directly to the developer it slows down the dev process and seems (to me) to promote evenness in the development. I add about 1g per 500ml but more or less can be tried. Diluting developer is not always the best way to go in order to be able to extend development time: extreme dilutions (past 4x) can require an obsessive care with agitation because of the quick local capacity depletion. It is better to use baking soda here in conjunction with moderate dilution. Also, in the opposite direction, baking soda can accelerate the process (ie, when developing something like TRI-X in Microdol-x (1+3) and you want vigorous negatives quickly. First, you must convert the baking soda to sodium carbonate by heating some in a pan on the stove. When you do this tiny, harmless 'volcanos' erupt (that is a poetic attempt) and let off small jets of powder and steam. Don't do more than an ounce or two at a time or you will have a little stovetop mess. And, VERY IMPORTANT HERE: understand that the pan gets much hotter than if you were boiling mere water. Keep heating the baking soda until the 'volcanos' die down. The powder, at this point flows like a liquid when you move the pan. You have just created sodium carbonate in, I think, the 'mono' version. - David Lyga</p>

[leicaglow]

<p>Hi David, is your goal to use a mild accelerator to get even development with stand or semi-stand development? Have you considered also looking at the excellent effects of another household item: Borax? I use this in stand development all the time. Also, Sodium Metaborate works pretty well, but I prefer ordinary Borax, and you don't have to worry about what the cops find on your stove<g>.</p>

[wendell_kelly]

<p>There really isn't any need to calcine baking soda at home to prepare sodium carbonate. You can buy sodium carbonate directly at many supermarkets. It is sold as "washing soda" and found in the same aisle as laundry detegents.<br>

The Arm and Hammer product called "Super Washing Soda", sold in a yellow box, is sodium carbonate monohydrate. I've been using it for years to make up D-72 paper developer (very similar to Dektol).</p>

 

[david_lyga]

<p>Yes, I know that washing soda is sold but there are many locales where it is difficult to purchase. Baking soda 'does both' (accelerate, when changed to sod carbonate, and hold back when used directly) and does so rather conveniently and cheaply. Also, in my original post I warned about not diluting film dev more than 4X (ie, 1+3). This caveat does NOT apply to Dektol (D-72) which has considerably more developer constituent (metol/HQ) and can safely be diluted 8x (ie, 1+7). Yes, Borax does also promote even development but, working with baking soda directly (to be able to extend development times) I find that it just seems to 'go well' with developers. I am not a chemist but I do pay attention and have done countless experiments over the years (since 1964 !). - David Lyga.</p>

[conrad_hoffman]

<p>I'm in favor of just buying the stuff, along with the raw chemicals for whatever developer you want to mix. IMO, one's consistency will be better over the long run by mixing to a specific formula. Regardless, I'd caution anybody wanting to heat bicarb to *never* accidentally grab a Teflon coated pan, lest you poison yourself. I think some pets (birds?) are also highly sensitive to overheated Teflon. Use only cast iron.</p>

[wendell_kelly]

<p>May I suggest that anyone wishing to pursue Mr. Lyga's suggestions also consult Anchells books on film developers and darkroom chemistry?<br>

Dektol and D-76 (as well as many other developers) are so-called MQ developers. They use a combination of Metol and Hydroquinone (the M and the Q), in a pH buffered solution, as the developing agents.<br>

At high pH (sodium carbonate-rich developers, e.g. D72) both the metol and hydroquinone are active. At moderate pH (borax buffer, e.g. D76; Metol is the principal active component - see Anchell). Tweeking Dektol with bicarbonate seems, to me, just to be adjusting the pH to vary the contributions of Metol and Hydroquinone to the final result. Why not do this directly by compounding a developer with a buffering chemistry in the desired range rather than attempting to upset the buffer chemistry of a well-proven system. a system that was designed to be difficult to upset? I offer these comments as a retired inorganic chemist, industrial R&D, and an enthusiastic darkroom drudge for 45 years.</p>

<p>Regarding the availablity of washing soda in the US: while there are, no doubt, localities where the stuff simply isn't available, I've lived in a number of areas from the Midwest to the East Coast and have always managed to find washing soda, usually for doing laundry. If you have only a single supermarket handy, and they don't carry washing soda, then you are out of luck. If you have several supermarkets, or hardware stores, try another store. People have been using the stuff for a century to clean greasy clothes. It works quite well in the washing machine should you been outside tuning your MG, JAG, rototiller, lawnmower, or John Deere.</p>

<p>I live in the NE USA, in a county with only five supermarkets, three of any size. It surprises me, at times, how different the stock is in specialty items.</p>

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[jpo3136b]

<p>In my area, they'll sell it labeled as an "Oxygenator" for the laundry. "Oxy" this or "Oxy" that. Oxy-spot-remover. Check the label. It's usually there, just few companies are willing to call it "washing soda" anymore. Ingredients will usually be sodium carbonate and sodium percarbonate and who knows what else. J.</p>

[charlie_goodwin]

<p>Household substitutions:<br>

Sodium Carbonate = Washing soda = Arm & Hammer Washing Soda<br>

Borax = 20 Mule team borax<br>

Acetic Acid = White Vinegar<br>

Sodium Hydroxide - Red Devil Lye - hard to get now - careful with this stuff.</p>

<p>C</p>

<p> </p>

[wendell_kelly]

<p>Anything with percarbonate in it is completely unsuitable for use in a developer. The percarbonate with consume the developing agents. Just use straight washing soda.</p>

<p>If you can't find Red Devil Lye in a grocery store/supermarket a hardware store will have it or Drano. Both are likely to be available as long as grease plugs kithchen drains.</p>

[lex_jenkins]

<p>Red Devil lye is still readily available here in Texas. A few years ago I concocted a universal developer using the basic ingredients usually recommended. It produced high fogging on film and paper, as well as staining along the paper edges due to infiltration, but showed potential if I'd cared to tweak it further.</p>

<p>I also tried the method David mentioned in the initial post. Frankly, it's not worth the trouble unless true washing soda cannot be found.</p>