TEA is a slow destroyer? (yellow and red)

Rudeofus · Jan 31, 2012

Gerald C Koch said:
Just to add to what PE said; you should never heat chemicals in a microwave oven or regular oven that is also used for food.

This is exactly my problem with all these TEA based recipes. While it's convenient to have a solvent which prevents your developer from oxidation, works as a silver solvent and has high pH in aqueous solution all at once, the recipes recommend preparation of stock solution at temperatures beyond 100°C, which means people with no access to a chem laboratory (i.e. most home brewers) will inevitably do this in their kitchen at some point in time.

I understand the fascination a simple and long lasting stock developer solution has on many home brewers here, but I wish these recipes didn't involve heating of toxic and possibly carcinogenic substances.

Photo Engineer · Jan 31, 2012

Muahaha! I have my own "secret" method! It is totally safe and everything dissolves.

Actually, there is a safe method that uses nothing higher than 40 deg C (100 F) and a water bath. I may describe it someday.

PE

Gerald C Koch · Jan 31, 2012

I have mentioned on several threads that Dimezone, Phenidone, and ascorbic acid will dissolve in glycols or TEA at room temperature if one is patient. What I recommended was putting the developing agents and glycol in a bottle and gently shaking it periodically until the solids dissolve. The bottle can be gently warmed, say to 50 C, during this process to speed solution. If one uses a mixture of glycol and TEA then the TEA should be added after the solids dissolve and the solution has cooled. I have used a 1:1 mixture of glycol and TEA in the final concentrate.

Photo Engineer · Jan 31, 2012

See how simple it is? Jerry got one method right off. There are several others that are almost identical!

Oh, I like mine stirred, not shaken!

PE

Rudeofus · Jan 31, 2012

I take your point that one could mix PC-TEA or the like at elevated room temperature by adding a little bit of patience to the mixing procedure - but that is not what most instructions posted online state. I have argued in another thread that home brewing is a field one can easily enter - it does neither require a PhD in chemistry nor 5 digit amount of money to get started. It takes only one silly mistake to be disabled for life, though. Given this I suggest we consider (there was a url link here which no longer exists) again when we post recipes, especially recipes aimed at casual users like those which create long lasting stock solutions.

Sorry for my OT rant.

Photo Engineer · Jan 31, 2012

There was also a long thread pointing out the dangers of heating organic solvents in the microwave or on the stove.

PE

albada · Jan 31, 2012

Gerald C Koch said:
Standardizing on a mix of TEa and DEA is OK but makes your formula non-portable to others.

We have this problem with other chemicals too. Looking through MSDSs, I noticed that the Formulary's sodium sulfite and sodium metaborate are graded for 90-100%. Being 10% off in an alkali could cause a significant change in pH and activity. I'd prefer at least 95%. Is there a source of chemicals with tighter tolerances?
BTW, the Chemistry Store's MSDS does not state the grade of its sodium sulfite.

Mark Overton

Photo Engineer · Jan 31, 2012

Mark;

The Sulfite is probably contaminated with Sulfate due to oxidation. Not sure about the Borate.

In any event, price skyrockets when you go after analytical grade or ACS Certified.

PE

Gerald C Koch · Jan 31, 2012

albada said:
We have this problem with other chemicals too. Looking through MSDSs, I noticed that the Formulary's sodium sulfite and sodium metaborate are graded for 90-100%. Being 10% off in an alkali could cause a significant change in pH and activity. I'd prefer at least 95%. Is there a source of chemicals with tighter tolerances?
BTW, the Chemistry Store's MSDS does not state the grade of its sodium sulfite.

Mark Overton

Hi Mark,

The Chemistry Store MSDS does however say that their sodium sulfite contains 3.2 % water and no volatiles. I have used it for many years without any problems.

Their any several grades of chemicals which are allowable for specific purposes. For example, sodium sulfite is used in the food industry and so there is a food grade. This guarantees that there are no impurities dangerous to human health present. Their is also a photo grade which assures that the a chemical does not contain any impurities that can cause problems when used in photography. One would think that photo grade would be vary pure but this is often not the case. There is also a technical grade which is intended for manufactures. Other grades are USP and reagent grades. There are more but we need not be concerned with them.

Jerry

Gerald C Koch · Jan 31, 2012

Rudeofus,

No your coments are proper and well taken.

The thread you mention was directed to certain people who were mixing chemicals together with no knowledge of what they were doing. This is why the warning was given to first read the MSDS's for all the chemicals being used. An MSDS will state whether something is flammable, or toxic, ... It will also list which chemicals should not be mixed together. There is a lot of useful information available if one takes the time to read it. Unfortunately, there are people who cannot follow directions. Each year several dozen people are burned trying to deep fry turkeys. They don't read the directions that come with the fryer. Most of the chemicals used in photography are safe when used properly. The chemicals mentioned in this thread are safe if one knows what they are doing.

Jerry

Photo Engineer · Feb 1, 2012

I think that we should be clear on one thing regarding the MSDS. It is a Safety Data Sheet, not a statement of purity. It tells fire and medical crews how to handle misuse or accidents such as spills and ingestion and it lists a possible range of possible impurities, not the absolute content.

If you don't believe this, look at the MSDS for HC110 or something like that, or perhaps XTOL.

Purity is given in grades and is often listed on the side of a drum or bottle as "Assay". Grades include Analytical, Practical and Technical grades. In among other grades are Photo Grade and Food Grade. In many cases, you cannot use Food Grade for Photographic use.

PE

albada · Feb 1, 2012

Gerald C Koch said:
Here are approximate pH values for a series of 4% solutions; TEA 99% 10.1, TEA technical grade 10.4, DEA 11.4, MEA 11.9

Tech grade TEA is pH 10.4, but my TEA is 10.8.
What do folks think of that?
I know I know, I should like my TEA hot.

Mark Overton

Photo Engineer · Feb 1, 2012

Mark;

Water content will change pH values to some extent.

albada · Feb 2, 2012

Photo Engineer said:
Mark; Water content will change pH values to some extent.

Can watering-down TEA by say 5% cause its pH to rise by 0.4? The 0.4 is so large that I wonder if I got a bad batch of TEA.

Mark

Tronds · Feb 2, 2012

albada said:
Can watering-down TEA by say 5% cause its pH to rise by 0.4? The 0.4 is so large that I wonder if I got a bad batch of TEA.

Mark

No. Diluting an alkali 1:1 with water will make the pH DROP by about 0.3.
That is unless you have an overly alkalic water.

Photo Engineer · Feb 2, 2012

To be clear on this, pH has no real meaning in pure organic liquids and so any measurement is ambiguous. pH is the measure of H2O in equilibrium with H+ and OH- and you can see that in pure solvent all three of these can be totally absent and so you are measuring the electron excess or absence rather than the equilibrium.

As you add water, the HOH (water) begin to disassociate and register true pH, but it is still interfered with due to the huge amount of organic solvent present.

That said, all I can suggest is for you to try the experiment as the results could go either way. Intuition would say the pH would go down as you add water due to dilution, but equilibrium effects may force the pH to move up.

The presence of DEA will affect this to some extent, moving it upwards.

PE

Ryuji · Feb 2, 2012

If you think the synthetic rubber stuff on the eyedropper to be a decent oxygen barrier, you are totally mistaken. Don't trust anything other than glass, PET or metal to be a useful oxygen barrier at all.

Ryuji · Feb 2, 2012

Incidental presence of DEA by 15% volume of TEA makes significant increase in the activity of silver complex ions, even if the pH is adjusted to a predetermined target value by other means. This can mean faster development rate, more physical development, coarser or finer grain (depending on how the other factors affect) and so forth. Be careful. For research purpose, always use pure TEA, DEA, etc., so that you know exactly what you are using.

TEA is a slow destroyer? (yellow and red)

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