PC-glycol

[eSPhotos]

Just curious ...
Any reason why I cannot disolve 25g of Sodium carbonate into 100ml of PC-glycol?
Yes, I am thinking of single part PC-glycol.
Thanks

 

[jochen]

Hello,
Sodium carbonate is an inorganic salt and consists of two positive Sodium cations and a negative carbonate anion. Such salts are well soluble in the highly polar solvent water which can solubilze the ions by its dipolar molecules. Glycol is a rather polar organic solvent but not polar enough to dissolve such high amounts of salts. The organic developer substances like phenidone, metol or hydroquinone are better soluble in glycols. As an alkali in glycol based concentrated developers often triethanolamine is used.

 

[eSPhotos]

Thanks for quick response, jochen. You must be a chemist...
I think I understand and am hearing 'this will not disolve ...'

 

[Gerald C Koch]

The general rule you need to remember is "like dissolves like." Inorganic (ionic) compounds dissolve in inorganic solvents (like water) and organic compounds dissolve in organic solvents. There are however many eceptions.

 

[MichaelMadio]

@eSPhotos: You might be interested in PC-TEA ... TEA is both the solvent and alkali. Another alternative is PCB (19g borax + 6g ascorbic acid + 0.15g phenidone in 1L water) ... 1L will process 12 rolls of film.

 

[eSPhotos]

PC-TEA is ideal but I happened to have some glycol. The reason I am asking in the first place is to avoid measuring small quantity of phenidone - there is another thread on this issue so I am not the only one.

How about dissolving 25g of carbonate in 100ml of water (at 50 degrees C) then mix it with 100ml PC-glycol? I doubt it will have infinite shelf life but I would guess long enough to not worry about sudden death syndrome.

thanks

 

[MichaelMadio]

I think that will work as I have had success with the above mentioned PCB which works out to 60mL of PC-Glycol in 1L of alkali (borax) solution. You will still have to make a working strength solution from this stock at around 1:25 for use. I've been down this road myself as I like phenidone/c developers but had no interest in acquiring TEA and found PCB to be the most practical. 60mL of pc-glycol in 1L alkali solution is easy to measure and you only need to do it every 12 rolls. I use a 2% borax solution (you can keep this pre-mixed) but I suspect a 0.5% sodium carbonate solution would work as well. The advantage is that you do not need to prepare any developer before processing unless mixing a fresh batch and if you keep the working strength developer for only 12 rolls/L you have little worry about any sudden death.

 

[Gerald C Koch]

How about dissolving 25g of carbonate in 100ml of water (at 50 degrees C) then mix it with 100ml PC-glycol? I doubt it will have infinite shelf life but I would guess long enough to not worry about sudden death syndrome.
thanks

Adding water to the glycol solution really defeats the purpose of using glycol in the first place. A glycol solution is much less prone to oxidation than a water based solution. This is the same method that Kodak used with HC-110 which ccontains no water whatsoever and has legendary keeping properties.

Adding carbonate to the developer would also decrease the storage life.

 

[MichaelMadio]

I generally agree with Gerald above but I found something interesting. When using something like PCB mentioned above, it appears to have enough excess ascorbate to last for 12 rolls within a reasonable amount of time ... what that time is I don't know but when I first tested PCB I made a batch that kept for over 12 weeks without any loss of activity. I do not think it would last nearly indefinitely like HC-110 but it seems to last long enough to get through 12 rolls of film. If you really want to play it safe, keep the water out of the PC-Glycol for the reasons mentioned above. You can always make the PC-Glycol more dilute so it's easier to measure and if you keep a jug of pre-mixed alkali on hand it's really easy to prepare. Incidentally my preferred developer is PC-Glycol at 1:125 in a 1% sodium metaborate solution and 0.2g/L potassium bromide (I call it PCM).