Sodium Metaborate from Borax and Lye

MichaelMadio · Jun 28, 2007

I'm looking to make Sodium Metaborate from Borax and Lye but am confused as to the amounts to be used. The Darkroom Cookbook states that 100g of Sodium Metaborate = 9.5g Lye + 45.5g Borax while I find other references on the Internet that state that 100g of Sodium Metaborate = 14.5g Lye + 69g Borax. So with myself being a non-chemist and just a recipe follower, which one is right?

Mike Wilde · Jun 28, 2007

Practical, not theoretical apporach

I am pretty sure that I saved this from a Pat Gainer post.

Anyways - away we go...

The biggest problem I have faced when mixing metaborate is how pure is the hydroxide? It will absorb humidity and carbonic gas, so it's weight/activity will change as it ages. So, when one mixes the traditional borax/hydroxide formula, the results may vary significantly.

After lots of experimentation, I've devised the following to be able to mix it without the help of a pH meter: The trick is to make a concentrated solution, and mix it in a clear glass container (the concentrate will give visual clues).

25% metaborate solution (as per Michael Gudzinowicz tetrahydrate formula):
Water (room temp - some 20C/68F) - 400cc
Sodium hydroxide - 19g (pour slowly, stirring; usual precautions apply)
Borax - 90g (pour slowly, stir until dissolved, may take a couple of minutes).

Two things may happen:
-If the hydroxide is pure, there will be no borax left and the solution will be clear when stirred. And there will be no metaborate (transparent) crystals in the bottom.

-If the hydroxide is not pure (my case), there will be borax left, the solution will be cloudy when stirred, due to being a mix of dissolved metaborate and un-dissolved borax.

Start to add hydroxide slowly, stirring, 1g a time (or the equivalent in cc of an 20~50% hydroxide solution, easier) until the solution clears

When standing and there are just some borax crystals in the bottom of the solution when not stirred. DO NOT OVERDO.

If the crystals loose the borax whitish look and become kind of transparent (metaborate crystals), you've overdone the hydroxide, and the solution pH will be higher than it should be.

This is like a titration in which borax is the indicator. Let it stand for a couple of minutes (decant) and slowly pour the liquid in another container. Do not pour the crystals that are at the bottom.

Add water to 500cc.

This 25% solution has been mixed more than once, and it passes the basic (ouch!) test - dilute it to 1% and pH is 11.1 (within my pH meter precision). I've frozen it to 0C/32F and left it stand for 2 days at room temp and no crystallization.

jim appleyard · Jun 28, 2007

Or, you just buy metaborate. It's pretty inexpensive.

I used to make Rodinal, et al, with sod. hydroxide by using Red Devil lye. However, lye has been taken off the shelves in the supermarkets and hardware stores, at least here. I've read where this is due to lye being use in the making of meth.

Anyway, I just buy my Rodinal from Freestyle and my metaborate from Artcraft and save all the hassle of mixing and paying for hazmat shipping fees to get sod. hydroxide.

Mike Wilde · Jun 28, 2007

Lots o lye here though

Yes, sodium hydroxide, a very versatile base. On its own in water it is even a very good paint stripper for cleaning up old metal furniture hardware that has been painted over a zilloin times. I just filter it thougha stainless steel mesh after paint strippling, and still can use it to go on to make soap.

I can still buy red devil lye at my local home hardware. I also do my own superfatted glycerin rich soap, after damaging the skin on my hands many years ago. I did a calculation a while ago, and I could buy bulk lye for the making of 93 lots of soap for the cost of 13 cans of red devil lye. Consequently I now have about 40kg still on hand in a 20L plastic pail (with a well fitting lid) sitting up high on shelf in the basement, well out of reach of curious hands.

gainer · Jun 28, 2007

MichaelMadio said:
I'm looking to make Sodium Metaborate from Borax and Lye but am confused as to the amounts to be used. The Darkroom Cookbook states that 100g of Sodium Metaborate = 9.5g Lye + 45.5g Borax while I find other references on the Internet that state that 100g of Sodium Metaborate = 14.5g Lye + 69g Borax. So with myself being a non-chemist and just a recipe follower, which one is right?

The formula I have that I trust, to make a 10% metaborate solution, is:

14.5 grams sodium hydroxide
69 grams borax
Water to make a liter.

If you buy metaborate, don't be confused by the 4 mol-8 mol stuff. You would use the same weight of either in any formula. sodium metaborate 8 mol has twice the molecular weight of the 4 mol. A certain weight of either one has the same number of molecules. One turns into the other at a certain temperature without any change in weight.

BradS · Jun 29, 2007

I had this same question...I'm not a chemistry person so, it took me several hours to figure this out but, here's the way I see it....

2NaOH + Na2B4o7(10H2O) + 5H2O <-->> 4NaBO2(4H2O)

2 mols lye + 1 mol Borax (in water) is equivalent to 4 mols Kodalk in water

80g lye + 381.37g Borax (in water) is equivalent to 551.42g Kodalk in water.

divide each of these by 5.5142 and, I beleive, you get the quantities provided by Mr. Gainer.

gainer · Jun 29, 2007

If you are wondering why the amounts of sodium hydroxide and borax don't add to 100 grams, it's because there is some water of crystallization that comes with the Kodalk or sodium metaborate that you order as such that is supplied with the water needed to make one liter of 10% solution. If you were to remove the water from a liter of the 10% solution by vacuum evaporation, keeping the temperature below about 100 C, the remains would be sodium metaborate as you would purchase it.

MichaelMadio · Jul 3, 2007

Thanks all. Very helpful.

dancqu · Jul 3, 2007

An alternative offering the same ph and still good
buffering is the combination of sodium carbonate and
sodium bicarbonate. The ph of the carbonate is 11.5 +/-
and the bicarbonate 8 +/-. Any ph twixt those two can
be achieved. Dan

gainer · Jul 5, 2007

I stay away from carbonates because of the calcium and magnesium in my well water. I use rain water or dehymidifier condensate when I must use carbonate. Otherwise, I have no objection to carbonates.

I do think borax has a greater buffer capacity, but a narrower pH range. If I can, I use borax. The metaborate is sometimes convenient if you have it on hand, for neutralizing some components and leaving a considerable quantity of borax equivalent. Borax alone is quite sufficient for a phenidone-sodium ascorbate developer. When the ascorbate is not directly available, the acid can be neutralized by bicarbonate, carbonate or sodium or potassium hydroxide.
I think that with borax, it is easier to calculate how to get a given pH as long as that pH is 9.3.

MichaelMadio · Jul 5, 2007

Patrick,

It's interesting you mention borax instead of carbonate. I've been using your PC-Glycol formula (phenidone + ascorbic acid) with carbonate and metaborate. I prefer the results with metaborate and I'm fresh out so that's why I thought of mixing my own. However, if I can use borax directly, that would be even more convenient than using a home-brew metaborate solution. What proportions do you suggest?

gainer · Jul 6, 2007

The problem here is that the ascorbic acid is not neutralized until you add the alkali. My original recipe used triethanolamine as the alkali to be added just before use. Later, I found that using TEA as the solvent provided sufficient alkali that a second solution was not needed. This is, of course, PC-TEA. I doubt that borax alone would work well as the second solution. PC-Glycol and PC-TEA are high-dilution developers of pH somewhat higher than borax alone can provide. OTH, a liter of working strength PC-Glycol at 1:50 dilution contains only about 0.2 grams of ascorbic acid. The virtue of metaborate in this situation is that it can provide a high enough pH. Highly diluted developers usually depend on low buffering for the supposed accentuation of edge effects.
Just for your own education, you might try a comparison between PC-Glycol and the PC-Borax water solvent developer in my article on experiments with Metol and ascorbic acid. It is easy to mix and may be reused without replenishment. The normal development time is 7 minutes at 68 F, so it could be diluted 1:1 or so. This is not a highly diluted developer, and the pH will be right around 9.3. You may be surprised at its sharpness and gradations.

gainer · Jul 6, 2007

I have just found that the PC-Borax may be simplified by adding more borax when there is no ascorbate available. A simple formula is 1/4 teaspoon phenidone, well packed and levelled; 2 teaspoons ascorbic acid powder; 1 tablespoon + 1 teaspoon borax; water to make a liter. This leaves out the extra step of neutralizing the ascorbic acid with bicarbonate. If you are scrupulous, the weights are 0.81 grams of phenidone, 8.8 grams of ascorbic acid and 4 teaspoons of borax ( I forgot to weigh it. You can weight 4 teasoons of borax if you wish and use that weight for future reference.)

For some reason I am reminded of the time when my oldest son was learning to use a fork. Green beans were the most difficult. He would pick them up with his fingers, put them on the fork, and use it to transport them to his mouth. Later, he learned to use mashed potatos to stick the beans to the fork, like us grownups.

dancqu · Jul 6, 2007

gainer said:
I have just found that the PC-Borax may be simplified
by adding more borax when there is no ascorbate available.

This leaves out the extra step of neutralizing the
ascorbic acid with bicarbonate.

Our planet is a safer place; no fizz, no CO two.

How easy it is for the obvious to escape us; that the
more alkaline borax does neutralize and make alkaline
a solution of ascorbic acid. I run up against the
obvious every now and then and wonder why
all these years .... . Dan

gainer · Jul 7, 2007

I guess the reason I didn't try borax alone with phenidone and ascorbic acid is that I didn't calculate how much it would take, but ass-u-med that it would be more than would dissolve. I finally did the calculation for 0.05 moles of ascorbic acid. It only requires 0.025 moles of borax, which amounts to 9.55 grams, to convert the ascorbic acid to sodium ascorbate and H2B4O7. Now if the borax is in excess of that amount, there will be a mixture of borax and tetraboric acid that should also be a good buffer. As much as 30 grams of borax will dissolve in a liter of water at 20 C.

PH alone is not the only factor that affects activity, even when all else is held constant. The process is a dynamic one, as is every process we can observe, which means that it takes time to complete it. The speed of reaction depends on the local pH. The equilibrium pH of a borax solution depends little on the equilibrium concentration, but the local concentration of boric acid is a fluid flow process as well as a chemical one. The higher the equilibrium concentration, the smaller the relative local change due to the acidic reaction products of development in an ascorbate replenished bath. There's a lot more to it, but this is all I can comprehend at the moment.

dancqu · Jul 7, 2007

gainer said:
As much as 30 grams of borax will dissolve
in a liter of water at 20 C.

I read 50 + grams at 20 C. I've managed near
6% at a likely 22 C. Dan

gainer · Jul 8, 2007

In fact, if you add enough borax to make a saturated solution and filter or siphon off the clear part, the equilibrium pH will still be about 9.3. I found that the same developer works as well for paper as for film.

The idea here is that the ascorbate-borax combination will not develop film, but will maximize the speed and capacity of any given amount of phenidone. You can test this part of the hypothesis by mixing 8.8 grams of ascorbic acid with a saturated solution of borax in a liter of water. You will not see any useful blackening of a film snip in 2 minutes. Now add 8 ml of a 10% solution of phenidone in glycol or 90% isopropanol and see how long the snip takes to turn black. If you wish, you may add the phenidone first, but without either sulfite or ascorbate, it will oxidize quickly, so add a pinch of sulfite. Now compare the blackening time of this solution with the phenidone-ascorbate-borax one.
You will see that the PCB solution, even diluted 1+3 or so, is a 2 minute paper developer.

dancqu · Jul 8, 2007

[QUOTES=gainer;489577]
"In fact, if you add enough borax to make a saturated solution
and filter or siphon off the clear part, the equilibrium pH will still
be about 9.3. I found that the same developer works as well for
paper as for film."

So, life is now easier. Skip the effervescence and head straight
for an ascorbate via borax. Now how much borax decahydrate
above that needed to neutralize the A. acid is needed to fully
activate. Perhaps much less than a saturated solution? I use
all chemistry one-shot so wish not throwing unused portions
down the drain.

"The idea here is that the ascorbate-borax combination
will not develop film, but will maximize the speed and capacity
of any given amount of phenidone. You can test this part of the
hypothesis by mixing 8.8 grams of ascorbic acid with a saturated
solution of borax in a liter of water. You will not see any useful
blackening of a film snip in 2 minutes."

"Now add 8 ml of a 10% solution of phenidone in glycol or 90%
isopropanol and see how long the snip takes to turn black. If you
wish, you may add the phenidone first, but without either sulfite
or ascorbate, it will oxidize quickly, so add a pinch of sulfite.
Now compare the blackening time of this solution with the
phenidone-ascorbate-borax one."

So the formula and method suggested is this: To a liter volume
of water saturated with borax add 8.8 grams of ascorbic acid and
0.8 grams of phenidone.

I'll suggest an alternative formula and method based upon that
quoted above. To 750ml of water add 8.8 grams of ascorbic acid.
Then add 0.8 grams phenidone. Last add some predetermined
amount of borax decahydrate. That amount of borax is still
a question. Some specific amount or range should be set.
Save that way on filtering and surplus down the drain.

"You will see that the PCB solution, even diluted 1+3 or so, is a
2 minute paper developer."

So one liter makes 4 or more for paper and I'd guess 8 or more
for film. Well I've got the phenidone, ascorbic acid, and borax.
May have to give that a try and see how it does against the
metol, sulfite, and carbonate Ansco 120/Beer's A brew.
Those last also good for film or paper. Dan

gainer · Jul 8, 2007

Why are you worried about the predetermined amount of borax? Do you want the solution to be reduced in activity before development is complete, or at the same time? If you are thinking of controlling sharpness by local starvation of the developer, I doubt you could prove that it is any more effective at getting sharp edges than the saturated solution. I don't mean prove theoretically, but actually, by a comparison.

I can calculate how much borax is required by the fact that the molecular weight of ascorbic acid is 176 and that of borax (The 20 Mule Team stuff you get at the soap counter is the decahydrate) is 382, and that 1 molecular weight of borax will make 2 molecular weights of sodium ascorbate out of 2 molecular weights of ascorbic acid, as well as 1 molecular weight of tetraboric acid. The solution is still acidic until more borax is added. How much more depends on the pH you want and how much buffering you want.

Before you start calculating how to get edge effects from local starvation of the alkali or the developing agent, remember that the ascorbate is practically inactive at any pH you can get from borax, but it is quite active at regenerating the phenidone. 8.8 grams of ascorbic acid make 0.05 molecular weights of the ascorbate, which from the figure in Mees & James I find to be about twice the amount where the curve begins to flatten. The pH for those data is stated to be 8.5.

There is the other dynamic effect of concentration that enters into local pH. When a molecule of ascorbate is used to regenerate phenidone, it makes dehydroascorbic acid which will be neutralized by the borax at a rate determined by the local concentrations of borax, ascorbate, developer potential and exposure of the film. (My terms may be a bit homey.) Agitation enters into the picture as well. (I made that pun by accident.) As a result, I am not about to try to compute the outcome of a comparison between different methods of controlling edge effects. I can say I am very pleased with the sharpness, but the only way I can demonstrate it for you is by scanning.

It's not so hard to mix a batch. You will find that more than 2 tablespoons of borax per liter is a waste of borax, but not much of a waste of money.

dancqu · Jul 9, 2007

gainer said:
Why are you worried about the predetermined amount of borax?

"...add enough borax to make a saturated solution and filter or
siphon off the clear part,..." Quote from post 17.

"...add enough borax..." How ever much that might be.
"...to make a saturated solution..." How ever much time it takes.
"...and filter or siphon..." Some additional hassel.

My suggestion was to adopt the conventional method.

In 750 ml H2O dissolve; so much ascorbic acid, so much
phenidone, so much borax. In that order. H2O to make 1 liter.
So what's wrong with that?

Besides, 50 to 60 grams of borax per liter may be an excessive
amount of some significance; down the drain so to speak. Dan

Robert Hall · Jul 10, 2007

Just to chime in a bit late... I have used what Brad stated for the past 4 years with lots of savings and no problems what soever.

(Good math there Brad!)

Maine-iac · Jul 10, 2007

MichaelMadio said:
Patrick,

It's interesting you mention borax instead of carbonate. I've been using your PC-Glycol formula (phenidone + ascorbic acid) with carbonate and metaborate. I prefer the results with metaborate and I'm fresh out so that's why I thought of mixing my own. However, if I can use borax directly, that would be even more convenient than using a home-brew metaborate solution. What proportions do you suggest?

I also use the PC-Glycol formula, but always with either metaborate or carbonate depending on the film. When using a fine-grained slower film like Fuji ACROS, the carbonate gives me the faster developing times I like (7-8 minutes) without an objectionable increase in grain. With faster films (Delta 400), I use metaborate which keeps me in the same developing time range, but with finer grain than the carbonate.

Personally, I find it simpler just to buy the metaborate; a pound jar lasts a long time. I use a teaspoon per liter of developer. It's pretty inexpensive and it's just not worth my time to make it myself from borax and lye.

Larry

gainer · Jul 10, 2007

I agree. Somewhere I gave a formula:
750 ml water
8.8 grams ascorbic acid
24 grams borax
0.8 grams phenidone
Water to 1 liter

This is conveniently approximated by:
2 teaspoons ascorbic acid
2 tablespoons borax
1/4 teaspoon phenidone, well packed and levelled
Water to 1 liter

It's not saturated, but has enough borax to bring the pH up above 9. My point was that even a saturated borax solution will not be much above pH=9.

When you get down to it, the buffering of the borax is what keeps activity nearly constant over a number of rolls. The ascorbate regenerates the phenidone but also decreases pH. An excess of borax keeps pH nearly constant. The molar concentraion of ascorbic acid begins at 0.05 and the product of regenerating phenidone is a dehydroascorbate which is somewhat more acidic than ascorbate. The initial conversion of ascorbic acid to sodium ascorbate by borax produces tetraboric acid which, in water, is equivalent to boric acid. The rate of regeneration of phenidone remains approximately constant until the molar concentration of ascorbate falls below 0.025.

Of course, I'm only theorizing. However, the results of experiments seem to agree. That doesn't mean that the theory is true, but that it is not detectably in error. Anyway, the theory is not mine.

The CRC handbook gives solubility of borax as about 2 grams/100 ml at 0 C and 170 at 100 C. A linear interpolation gives about 34 at 20 C. Linear may not tbe the proper way, so I can't argue with experimental evidence.

MichaelMadio · Jul 10, 2007

I finally had a chance to do some experimenting with this (new to me) information regarding borax. I mixed a developer using pc-glycol stock (10% ascorbic acid + 0.25% phenidone all in propylene glycol) 1:50 with 2 tbsp of borax per litre. With Tri-X at EI400 I really can't tell the difference from using sodium metaborate except I think borax needs a bit more time. I then went on to print some negs using the same formula as above (I typically use pc-glycol at 1:25 + sodium carbonate + potassium bromide) and the developer worked well for Ilford MG RC paper.

Some points of interest for me are that I now don't have to bother with sodium metaborate in my developers anymore and I can use the same developer recipe for both film and paper (this cuts my pc-glycol usage in half).

All I asked for was clarification on making sodium metaborate and I ended up doing away with it completely ... I can't complain. Thanks to all for the input.

dancqu · Jul 11, 2007

MichaelMadio said:
Some points of interest for me are that I now don't have
to bother with sodium metaborate in my developers anymore
and I can use the same developer recipe for both film and paper
(this cuts my pc-glycol usage in half).

All I asked for was clarification on making sodium metaborate
and I ended up doing away with it completely ... I can't complain.
Thanks to all for the input.

Likely the glycol could also be done away with although there
would be some trade offs. See Mr. Gainers most recent post
this thread. The formula he's posted has No glycol. Were I
to give it a try I'd play with concentrations and keep the
borax for a at time of use addition. Dan

Sodium Metaborate from Borax and Lye

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