Kodalk substitute?

BradS · Aug 10, 2006

I'm trying ot mix up a 2.0% solution of Kodalk. If Kodalk were available, I'd mix 20grams of it in water for a total volume of 1000ml.

A footnote to table XXXI in Developing by Jocobson & Jacobson (page 206, 1978 edition), says....

"*Kodalk is no longer available. For every 10g of Kodalk, add 1.3g sodium hydroxide and 6g Borax."

I measured out the 2.6g NaOH and 12g borax, added them to 800ml of boiled and filtered tap water (cooled over night) and topped it up to 1000ml. The resultant solution is cloudy...

My questions: is this really equivalent to a 2% solution of Kodalk and why is it cloudy? is it because of some impurity in the water or is that normal?

Gerald Koch · Aug 10, 2006

Kodak sold sodium metaborate tetrahydrate under the name Kodalk. This chemical is readily available from companies that sell photochemicals such as www.techcheminc.com.

While boiling water will remove the temporary hardness (calcium salts) it cannot remove the permanent hardness caused by magnesium compounds. My guess is that when you added the sodium hydroxide, magesium hydroxide precipitated out as it is only slightly soluble in water. I have always found it best to use distilled or de-ionized water.

gainer · Aug 10, 2006

Another bit of information: the 20 Mule Team people say that the only practical difference between the 4-mol and the 8 mol is that the molecular weight of one is twice that of the other. 100 grams of one contains as much sodium, boron and water as 100 grams of the other. IIRC, temperature make the difference.

gainer · Aug 10, 2006

I looked it up again. The 4-mol metaborate is stable above 53.6 C. Without any change of contents, it becomes the octahydrate. Enter Google with "sodium metaborate" and see what you get first on the list.

juan · Aug 10, 2006

gainer said:
Another bit of information: the 20 Mule Team people say that the only practical difference between the 4-mol and the 8 mol is that the molecular weight of one is twice that of the other. 100 grams of one contains as much sodium, boron and water as 100 grams of the other. IIRC, temperature make the difference.

So for we non-chemists, does this mean we can use 20-Mule Team Borax as a direct substitute for Kodalk? Or have I competely misread what you're saying?
juan

Gerald Koch · Aug 10, 2006

No, you can't, borax and sodium metaborate are two entirely different substances which produce different alkalinities when dissolved in water. Borax is only mildly alkaline while sodium metaborate is strongly alkaline. For example, substituting borax for sodium metaborate in a developer would severely reduce the activity of the developer.

BradS · Aug 10, 2006

Pat,

My lasting memory of three semesters of general chemistry is that we always managed to sneek M&M's into the lab and always seemed to break all the glaasware.

Are you saying that the 20 Mule team Borax that I've been pilfering from the laundry room is chemically the same as Kodalk? I thought that there was a slight difference in PH? (well, that was what I was hoping to achieve). What I want is an alkaline afterbath for D-23 that has a slightly higher PH than Borax but lower than Carbonate....I thought Kodalk was somewhere in the middle? Any suggestions?

Thanks to all who've replied so far.

I knew I should have made a trip to the supermarket for some purified water...maybe, I'll try again

Gerald Koch · Aug 10, 2006

BradS said:
What I want is an alkaline afterbath for D-23 that has a slightly higher PH than Borax but lower than Carbonate....I thought Kodalk was somewhere in the middle? Any suggestions?

I am curous. Since D-23 is already slightly alkaline due to the sodium sulfite, why do you need an alkaline afterbath?

BradS · Aug 10, 2006

Gerald Koch said:
I am curous. Since D-23 is already slightly alkaline due to the sodium sulfite, why do you need an alkaline afterbath?

I'm trying to get some more compression. It's the same old two bath story. Highlights develop out in the first bath (ordinary D-23) and shadows build a little more density in the second bath (alkaline afterbath).

I've been experimenting with various borax solutions and they all seem to work pretty well. Thought I'd also try something with a little higher PH. I have a pretty good supply of Sodium Carbonate but, I don't think I want to go quite that far - yet.

This all just experimentation. I'm pretty pleased with the results from D-23 followed by a 2-3% Borax solution.

Your earlier suggestion that magnesium hydroxied may be falling out of solution is an interesting one. Makes me wonder about my tap water...

Jim Noel · Aug 10, 2006

Borax is an acceptable second bath for Divided D-23, BUT it is not the same as sodium metaborate. Personally, I prefer the action of borax.

jim appleyard · Aug 10, 2006

You can also just simoly add 1 tsp borax to a liter of D-23. It raises the ph a bit and does the smae as your two-bath in only one step. I do Tri-X, EI 400 with spot meter, for 9 min in D-23 modified 1+0. Gives me good negs.

Gerald Koch · Aug 10, 2006

You could try a buffer mixture composed of sodium bicarbonate and sodium carbonate. Both are readily available. By varying the ratio you can get a variety of pH values, from that of sodium bicarbonate alone, 8.6, to that of sodium carbonate, 10.6.

gainer · Aug 10, 2006

BradS said:
Pat,

My lasting memory of three semesters of general chemistry is that we always managed to sneek M&M's into the lab and always seemed to break all the glaasware.

Are you saying that the 20 Mule team Borax that I've been pilfering from the laundry room is chemically the same as Kodalk? I thought that there was a slight difference in PH? (well, that was what I was hoping to achieve). What I want is an alkaline afterbath for D-23 that has a slightly higher PH than Borax but lower than Carbonate....I thought Kodalk was somewhere in the middle? Any suggestions?

Thanks to all who've replied so far.

I knew I should have made a trip to the supermarket for some purified water...maybe, I'll try again

I didn't say that. I said that the sodium metaborate 8 mol (so called because it's molecule has attached 8 molecules of water) has twice as many atoms in a molecule of everything that the 4 mol. There is no such relationship between borax and either of the metaborates.

Where we ordinarilly assume that different hydration states may be found with the same unhydrated crystal, as with the several states of sodium carbonate, where you must know the hydration state in order to make accurate measurements of active amounts, this is not true of the metaborate. I'm not even sure that the supplier can tell you what the hydration state when you get it, even though he may know very accurately what it was when he sent it under hermetical seal. It is of no practical importance to us, so long as it is metaborate, once it is dissolved in water. Whether wet or dry, borax and metaborate are different compounds with different chemical characteristics.

BradS · Aug 10, 2006

Hi Pat,

Thanks for your patience. Like I said, chemistry was never my strong point. The professor died of a heart attack about three weeks into the first semester and well...a female version of elmer fudd substituted. I am forever at a loss.

anyway, I think I should have read (there was a url link here which no longer exists) prior to posing this question (again).

Brad.

Jordan · Aug 11, 2006

Getting back to the "cloudiness" issue, my guess (like Pat's) is that you simply have undissolved borax. Borax is not hugely soluble in room temperature water -- heating really helps to get it into solution.

dancqu · Aug 11, 2006

jim appleyard said:
You can also just simply add 1 tsp borax to a liter of D-23.
It raises the ph a bit and does the smae as your two-bath
in only one step.

Off hand I can think of no reason borax should raise the
ph of an already very sulfited developer. Borax has a ph
lower than that of sodium sulfite. If the OP would like a
little higher ph in bath B he might try sodium sulfite.

For that matter every body could be A bath B
bath developing if all would only drop the acid or
water stop and adopt a low sulfite, one-shot, after
developer, compensating B bath.

Now why haven't I been doing that? Too much the
minimalist. I could do it the Gainer way; a 1/2 teaspoon
of sulfite in a 1/2 liter of water twixt developer and fixer.
I usually have more than enough density in the
highlight areas any way. Dan

Ryuji · Aug 12, 2006

BradS said:
I'm trying ot mix up a 2.0% solution of Kodalk. If Kodalk were available, I'd mix 20grams of it in water for a total volume of 1000ml.

A footnote to table XXXI in Developing by Jocobson & Jacobson (page 206, 1978 edition), says....

"*Kodalk is no longer available. For every 10g of Kodalk, add 1.3g sodium hydroxide and 6g Borax."

I measured out the 2.6g NaOH and 12g borax, added them to 800ml of boiled and filtered tap water (cooled over night) and topped it up to 1000ml. The resultant solution is cloudy...

My questions: is this really equivalent to a 2% solution of Kodalk and why is it cloudy? is it because of some impurity in the water or is that normal?

The given numbers are incorrect. Consult:

Dead Link Removed

For 20g Kodalk, you'd need 13.8g borax and 2.9g NaOH.

Ryuji · Aug 12, 2006

jim appleyard said:
You can also just simoly add 1 tsp borax to a liter of D-23. It raises the ph a bit and does the smae as your two-bath in only one step.

... thus the developer becomes more like D-76.

Ryuji · Aug 12, 2006

Gerald Koch said:
You could try a buffer mixture composed of sodium bicarbonate and sodium carbonate. Both are readily available. By varying the ratio you can get a variety of pH values, from that of sodium bicarbonate alone, 8.6, to that of sodium carbonate, 10.6.

Carbonates have poor buffering property outside pH of 5.5-7.5 and 9.2-11.2 range. I wouldn't use them for most fine grain film developers, which use pH range from 7 to 9.

Ryuji · Aug 12, 2006

dancqu said:
Off hand I can think of no reason borax should raise the
ph of an already very sulfited developer. Borax has a ph
lower than that of sodium sulfite. If the OP would like a
little higher ph in bath B he might try sodium sulfite.

Sulfite is a very weak alkali. The pH of D-23 is low enough to be raised by addition of borax.

For that matter every body could be A bath B
bath developing if all would only drop the acid or water stop and adopt a low sulfite, one-shot, after
developer, compensating B bath.

Now why haven't I been doing that? Too much the
minimalist. I could do it the Gainer way; a 1/2 teaspoon
of sulfite in a 1/2 liter of water twixt developer and fixer.
I usually have more than enough density in the
highlight areas any way. Dan

It would have little effect. Any such effect would be more effectively produced by suitably adjusting the developer (if necessary).

Gerald Koch · Aug 12, 2006

Ryuji said:
Carbonates have poor buffering property outside pH of 5.5-7.5 and 9.2-11.2 range. I wouldn't use them for most fine grain film developers, which use pH range from 7 to 9.

What the original poster Brad wanted was to make the second bath to convert D-23 into a two bath developer. This wasn't completely clear in the original post but I believe he wanted to do the majority of the development in D-23 and then use the second bath. He was having difficulty in obtaining sodium metaborate so I suggested a mixture of sodium bicarbonate and sodium carbonate to make a solution which would give the necessary pH of ~ 10.7 of a 2% solution of Kodalk. The usual divided D-23 uses a 1% solution of sodium carbonate which produces a pH of 11.4 which is a bit high for what he wanted.

Ryuji · Aug 12, 2006

Kodalk is a poor buffering agent for pH of 10.7, too. Kodalk gives good buffering property between 8.2 and about 10.

dancqu · Aug 12, 2006

Ryuji said:
... thus the developer becomes more like D-76.

With the addition of a little borax. But without the
hydroquinone it's still just so much bacon with out
the eggs. Good bacon though.

That pinch of borax added to D-76 is because of the
presence of hydroquinone. I'm quite sure it was an early
effort to counter act the rise in ph as the developer
aged. As the hydroxyl ion concentration increases
the borax hydrates, consuming as it were other
wise free hydroxyl ions. The tetraborate is
converted to the metaborate. Dan

Kodalk substitute?

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