Film Processing and Equipment    Main Page

I've seen a fair amount of discussion about PC-TEA so I thought I would give it  a go.

Here is the formula I used for this test.  I included the Potassium Bromide because I have some on hand.

 

                                                    PC-TEA Formula:

                                                    100ml TriEthanolAmine (heated to 160F)

                                                    9g Ascorbic Acid

                                                    0.2g Potassium Bromide (fog reduction)

                                                    0.25g Phenidone

A small amount of precipitate formed after mixing and settled on the bottom or stuck to the sides of the bottle.

I shot two rolls of TriX for a Zone density test and developed them in the same tank .  I mixed a PC-TEA dilution of 500 ml water with 10ml PC-TEA.  My development time was 12 minutes with one minute constant agitation and 10 seconds subsequent agitation each minute.  I used a water stop bath and a two bath TF-4 Fix.  After 30 minutes in a washer I hung the film and sprayed distilled water on both sides and let dry.

 

The results of the density measurements show a slight speed loss and an underdevelopment of about 2 stops.  Possibly the speed point would be reached if dilution were decreased and/or development time were increased.  The curve is the average of both tests.  The two tests showed no significant variance, and a t=test showed no difference at a p=.001.  The s-shape is typical for TriX when underdeveloped.

One possible reason for the underdevelopment is aging Phenidone.  Phenidone doesn't keep well in its powder form.  Making a liquid preservative solution with a fresh batch is recommended: (Darkroom Cookbook, pg. 28, Stephen Anchell)

750ml water (125F)

6g Sodium bisulfite

2g Phenidone

Cold Water to make a liter

 

100ml of solution is equal to 0.2 grams of Phenidone.

Another possible reason for underdevelopment is the use of Potassium bromide.  The reason for using potassium bromide is to restrain development and reduce base fog.   There is no evidence that base density and fog was reduced, but I can say that the fog was the same as  TriX in HC-110, bd+f = 0.24.  In this case so little Potassium bromide was used (0.2g) that it is unlikely to have caused underdevelopment.

 

 

                                                    * Densities based on average of two trials,  (t-test at P=.001)

Development Stats:  Two reel stainless steel tank, invert and twist agitation.

 

1.  No Pre-soaking

2.  Dilution mixed from concentrate.

3.  Initial agitation for 1 minute then 10 seconds every minute.

3.  Stop with water, four dumps about one minute

4.  Fix  TF-4 two bath method

5.  Wash

6.  Distilled H2O sprayed on while film is hanging.

7.  Let Dry

 

Densitometry - Measurements taken from center of negative using Macbeth TD-502.  Edge densities greater then center densities.  This is a function of the lens.  Other lens have different patterns.