PC-TEA redux

[AshenLight]

Hi,

After the minor *#$& storm I inadvertently caused in my last PC-TEA thread I'm hesitant to try again but here it goes...

Mr. Gainer's formula in the Darkroom Cookbook calls for 0.5g of phenidone but I've seen formulas posted that also specify 0.2g or 0.25g. What is the "official" amount of phenidone needed to achieve D76-like characteristics at 1:50?

Thanks,

Ash

 

[dynachrome]

PC-TEA

I know I have at least 2 different copies of The Darkroom Cookbook by Stephen G. Anchell. The one I have in my hands now is from 1994. I don't see PC-TEA or Patrick Gainer's name in it. I also just found a copy of The Film Developing Cookbook by Anchell & Troop from 1998. It also does not seem to have a reference to either PC-TEA or Patrick Gainer. My own recollection was that the amount of phenidone was 0.25 grams. I haven't made it in a while or I might be more certain. I found this amount more difficult to measure than the other two ingredients. I think I used an electronic postage scale and concerted from ounces to grams. At some point I will dig out my eBay-bought Mettler P1000 and find the calibration instructions. The next time I mix up PC-TEA I think I will make an amount starting with 400ml of TEA and then use volumetric measurement for the ascorbic acid and phenidone with the correspondingly larger volumes.

 

[ntenny]

After spending a few rigorous minutes with Google, I found a bunch of recipes calling for 0.25 g phenidone (per 100 ml of stock), and at least one suggestion for 0.225 g instead. The latter bumps the ratio of vitamin C to phenidone up from 36 to 40---the same as PC-Glycol---but I don't know if the difference is important.

Tiny weights are hard to measure, which is one reason I keep my phenidone stock in propylene glycol. It's pretty easy to measure out small volumes with a syringe that way. But given the apparently infinite shelf life of PC-TEA, mixing up a bigger batch makes sense too.

-NT

 

[srs5694]

There's now a third edition of the Darkroom Cookbook. I don't have it so I don't know its contents, though.

The original description for PC-TEA was in Photo Techniques magazine, March/April 2004. I don't have that issue handy, but the formula I copied from it that I do have handy specifies 0.25g of phenidone to make 100ml of stock solution. It's possible that Patrick Gainer has updated the formula since then for whatever reason, or it could be that the Darkroom Cookbook entry is a modification by Anchell or a typo, or maybe that version is to make 200ml of stock solution. Chances are it'll work either way, but you might need to adjust your times a bit. Perhaps Patrick Gainer will post his comments (he is active on APUG)....

 

[Alan Johnson]

Times below were probably established using the formula containing 0.25 gm phenidone, 9 g Ascorbic acid and 100 ml TEA.For other films see under unlisted data, it is suggested to use Xtol 1+2 times.
www.digitaltruth.com/devchart.php?Film=&Developer=PC-TEA&mdc=Search
3rd Edition Darkroom Cookbook p30 does give give 0.5g phenidone but I am using the original formula till there is more info on this.

 

[gainer]

I'm in my 82nd year of trying to remember what I did the previous year.

For a given concentration of Phenidone, there is a certain concentration of ascorbic acid above which the activity shows no measurable increase. The ratio levels off at about 40:1. Theoretically, the ascorbic acid is what is used up because the phenidone is replenished. Increasing the ratio has little effect on initial activity, but affects the quantity of film that can be processed uniformly in a given amount of working solution. If you want to do an experiment, see how much ascorbic acid you can dissolve in a given amount of TEA and add 1/50 that weight of Phenidone. Now do a test to find the development time for the kind of negs you like.

 

[Philippe-Georges]

I hardly dare to ask, but, what is the real up to date and ultimate PC-TEA formula (+ mixing instructions) now?

Philippe

 

[CBG]

I don't know that I'm current, PC-TEA is something of a moving target, but according to my copy of the latest version - the third edition - of the Darkroom Cookbook:

PC-TEA

TEA ...................... 100 ml
Phenidone .............. 0.5 g
Ascorbic Acid ......... 9.0 g

Heat the solvent, TEA, covered, in water bath and add the Phenidone and the Ascorbic acid.

Patrick Gainer suggests a 1:50 dilution. Developing times much like D-76 1:1.

 

[P C Headland]

Hi

The formula I've been using:

100ml TEA
9g Vitamin C
0.25g Phenidone.

I use 1+50 dilution, i.e. 10ml PC-TEA and 500ml water.

If I can't find a time listed for a particular film, I take the average of D76 1+1 and Xtol 1+1 times. If they are wildly different, I'll look at the Rodinal 1+50 time as well.

 

[Philippe-Georges]

Tank you both for the two slightly different formulas, I will be waiting for some more variations and take the mathematical average of the Phenidone, this will do for me...

Philippe

 

[ntenny]

While we're on the subject, has anyone done much experimentation with different dilutions of PC-TEA? Xtol, to which PC-TEA is often (naturally enough) compared, has the reputation of doing interesting things at higher dilutions (e.g., increased film speed), but I don't know whether PC-TEA shows the same properties. I can experiment, of course---I'm just wondering if anyone has already gotten around to it.

-NT

 

[srs5694]

Concerning dilutions, PC-TEA's recommended dilution of 1+50 is pretty dilute. This dilution works out to 0.049g of phenidone (starting with the 0.25g/100ml version) and 1.76g of ascorbic acid per liter of working solution. For comparison, Mytol (an XTOL workalike) at 1+1 dilution works out to 0.075g of phenidone and 6.5g of sodium ascorbate per liter of working solution, and DS-10 (another PC developer) 1+1 is 0.075g of Dimezone S and 4g of ascorbic acid. So it looks like PC-TEA at 1+50 is similar in developing agent concentration to XTOL or DS-10 at 1+3 to 1+4 dilution. Of course, there are other factors at work, but if one were to experiment with dilutions, I'd recommend starting by going less dilute rather than more. If going more dilute, be sure to use plenty of solution (say, 500ml per roll), otherwise you might exceed the capacity of the developing agents.

 

[ntenny]

Of course, there are other factors at work, but if one were to experiment with dilutions, I'd recommend starting by going less dilute rather than more.

Interesting, and I guess that makes handwavey sense given that PC-TEA is often compared to Xtol 1+2 (which is fairly dilute).

I've thought of going less dilute to shorten the developing times. With Xtol, my (limited) understanding is that one would expect slightly slower film speed, somewhat finer grain and decreased acutance due to the higher solvent levels, and a slight flattening of the characteristic curve (why?).

I don't know whether the same effects would obtain with higher concentrations of PC-TEA---I guess it depends largely on how much solvent action TEA is capable of. Is that known, in general terms?

-NT