For Michael Gudzinowicz re Post-Development Processing

Dr. Gudzinowicz,

 

I hope you don't mind my using this public forum to ask this question,

but I though it would be of interest to the community here as well.

 

After reading your article some years ago, I began using a two-bath

fix for films as well as prints. However, I have been confused about

some of the information in your article for some time. Your recent

reference to it in a recent thread on fixer capacity prompted me to

pursue my question further.

 

My question concerns the fixer capacities for one- and two-bath fixing

procedures recommended by Grant Haist that you quote in your article.

 

The capacities in the tables you list are given in rolls/gallon. These

capacities seem very low. Especially the "commercial" recommendation

by Haist for the single bath method of 25 rolls/gal, which would seem

to be in conflict with Kodak's own "commercial" recommendation

(ostensibly based on Haist's research) of 100 rolls/gallon.

 

This, and all the other capacity recommendations in your article seem

to make a lot more sense to me if they are rolls/quart instead of

rolls/gallon. This would also bring Haist's recommendation in your

article into line with Kodak's published recommendation.

 

For those interested in the whole article, the link is:

 

http://groups.google.com/group/rec.photo.darkroom/msg/c95fd5fc613c3bb2?hl=en&

 

Thanks in advance for you time and generosity.

The data is from Grant Haist's "Modern Photographic Processing" (Vol. 1; p. 641). I just checked it, and the volumes are given as gallons, not quarts, for typical acid fixers. There is a long tradition of the use of two bath fixing (publication in textbooks goes back to 1882), and in the older literature, a figure of 100 8x10 films per gallon of FIRST fixer has been used to demarcate the point at which contamination of the second fixer is a problem. The value used for commercial processing in Haist's table for film using two bath fixing is 60-70 rolls per gallon (not 25). That reflects a reasonable margin of safety for that type of processing. The table values were derived from a paper that used the silver levels in fixer (in equilibrium with paper) as a guide for capacity. Dr. Haist indicated that the book was critiqued by his staff at EKC, and it appears to be quite accurate.

 

I should rewrite the little guide on fixing, since I do have information that conflicts with most of the "quick" methods advocated by a number of people of which they are unaware or fail to mention.

 

I'd suggest that anyone interested in B&W processing acquire a copy of Haist's book through interlibrary loan, and at least read the last chapter on image permanence. Since its publication, the standards for print permanence have tightened up a bit. Another "dated" but useful book is Dr. Richard Henry's "Controls in Black and White Photography".

 

 

Haist, Grant Milford, 1922-

 

Modern photographic processing / Grant Haist.

 

New York : Wiley, c1979.

 

2 v. : ill. ; 24 cm.

 

ISBN: 0471042862

 

 

Henry, Richard J. (Richard Joseph)

 

Controls in black and white photography / Richard J. Henry.

 

2nd ed.

 

Boston : Focal Press, c1986.

 

270 p. : ill. ; 28 cm.

 

ISBN: 0240517881

Dr. Gudzinowicz,

 

Two years ago I ran across your article on two stage fixing...

 

1) I now use this process not only for my B&W film developing, but also my E-6 and C-41 developing as well... And my film thanks you!

 

2) I re-posted your article in its' entirety two years ago at:

http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=007dXZ

 

3) Most important of all, on the strength of your compelling arguments presented in your 1998 paper, other Photo dot Netters (with the notable exception of David Wood, of DR5 Labs fame) are also using two stage fixing with success.

 

A tip of the hat to you! :)

Hi,

While on the subject of fixer. Would the constant churning of conventional acid fixer in a jobo drum shorten it's working life and capacity ?. I never have found information on this.

 

Jennifer

Dan: Thanks, but I do not consider myself responsible for the information in the posts on two bath fixing. The summarization of research papers was done by Grant Haist and others. I've simply tried to pass along the conclusions.

 

Jennifer: I haven't seen any hard data on fixer life or capacity with Jobo processors, but Jobo should have had the data if anyone does. The only potential problem would be aerial oxidation of sulfite which could lead to sulfurization of the fixer. I don't feel that's a problem since the EKC instructions always have been to use constant agitation in roll tanks, and it doesn't seem to lead to a short life or rapid oxidation. Their recommendations should "compensate" for their standard method of agitation which isn't all that different from a Jobo.

Dr. Gudzinowicz

 

Thank you so much for the speedy response. However, my question about the discrepancy is still not entirely cleared up. It appears that, according to Haist, even when fixing to the less-exacting standards for "commercial" purposes, fixer has a much smaller capacity than manufacturers recommend: by about a factor of 4, which seems excessive.

 

Following is a comparison of major manufacturers recommendations with Haist's. All are assumed to be "commercial" and one-bath:

 

Kodak Rapid Fix (etc.): "120 8x10 sheets per gallon," one-bath method

 

Kodak Fixer: "100 8x10 sheets per gallon, "one-bath method (from Kodak's publication "Chemicals for Kodak Professional Black-and-White Films.")

 

Ilford Hypam Fixer: "24x135-36 rolls per liter," one-bath method without replenishment. This works out to roughly 100 rolls or 8x10 sheets per gallon. (From Ilford's fact sheet "Hypam Fixer and Hardener.")

 

Formulary TF-4 "For film the capacity is 15-20 rolls of film per liter of working solution." This works out to roughly 60+ rolls (8x10 sheets) per gallon using the one-bath method. (From the directions packaged with the TF-4 Fixer.)

 

Haist's recommendation quoted in "Post-Development Processing," "25 rolls per gallon, one-bath method."

 

Assuming that the recommendations from Kodak and Ilford are "commercial" recommendations for the one-bath method still shows a wide discrepancy between these and Haist's recommendation for "commercial" one-bath fixing. Haist's recommendation is for only 25 rolls per gallon, i.e. about one-quarter as much film area per gallon as the major manufacturers recommend.

 

This one-quarter factor was what led me to believe that the gallon units were a misprint and that the actual unit should be quarts (or better, liters, since that is what Haist was probably measuring with...).

 

In light of the disparity of the recommendations from both Kodak and Ilford, and that of Haist, I am still a bit unconvinced that his units (gallons) are correct. Since Haist worked for Kodak, and their recommendations are most likely still based on his research, I find it hard to believe that they would arbitrarily recommend running four times as much film area through a given amount of fixer than Haist seems to recommend. If Haist's figures are correct, that would certainly lead to overuse of the fixer and improper fixing of the film.

 

So, is there any explanation of this discrepancy that I am overlooking? I would love to understand this better, especially since fixing is such an important factor in permanence of both films and papers.

 

Thanks again in advance,

I, too, would like to thank Dr. Gudzinowicz for making available his paper on the chemistry of fixing. Since then I have used two-bath fixing as a matter of course. The paper also made me sharply aware that the vast majority of my previously processed negs are probably not fully fixed!

I'm sorry for the misunderstanding. Again, I've checked Haist's book, and the value for commercial processing of film is 25 8x10" sheets/rolls per gallon of fixer. His source is the following research paper: J.I. Crabtree, G.T. Eaton, and L.E. Mueller, "The Removal of Hypo and Silver Salts from Photographic Materials as Affected by the Composition of the Processing Solutions," J. SMPE, 41:9 (1943). The authors also published their findings in the "popular press" around that time. I don't recall the details of their papers, but that's where I'd go to resolve questions of accuracy, methodology and standards.

 

Of course, EKC's more recent commercial recommendations are for a wide variety of fixers, and the standards are not specified, though the trend has been to determine the amount of silver in the fixer and not residual silver in the paper. The insoluble silver complex culprits are not detected by spot tests used for convenient monitoring of residual silver of film and paper. The discrepancies may reflect different acceptable half-lives for the conversion of a commercial negative into the unprintable disposable one. The latter account for a high percentage of negatives in older family archives.