[pure-silver] Re: Kentmere Kentona Weirdness
----- Original Message ----- From: "Ray Rogers" <earthsoda@xxxxxxxxx> 
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, November 27, 2008 6:33 AM
Subject: [pure-silver] Re: Kentmere Kentona Weirdness
As the paper is quite old, I kind of doubt it is the new Kentmere product...
Uh let me check that- I just returned from there and heard they were having a bit of trouble with something... I will see what it was.
Anyway, it is curious... They themselves seem to have stated that diluted developer would help... and people testing the affected paper said that it was fine in dektol, yet one person, IIRC said it failed in polymax, (which I think(?)... Dave said was liquid Dektol)Also, seemes everyone agrees that some 6-12 months ago it worked fine.
I have read that cadmium may have had a stabilizing effect possibly with such papers but don't quote me.
About yellowing in general, I sometimes had trouble with it when I am too egar to inspect an image and I repeatedly pull it out of the developer to examine in the safelight beam... this I guess really increases the occurence of oxidation and with some paper/developer combinations it can cause drastic effects. Luckily, I only allow this to happen with test strips!
Also, that is a warmtone paper... anyway, let me go check the story on what Harman was having trouble with in the new kentmere line. 

Ray
I am not sure what part cadmium compounds play in paper emulsions. I've heard they were preservatives and that they were warm tone agents. It seems to be true that the shelf life of paper is shorter now than when cadmium was used but shelf life seems to vary all over the place anyway. For instance, I've had very old Brovira that worked fine and Kodak variable contrast paper that was unusable although only about two years old. The only paper I've had that had problems with markings was some very old Agfa paper that was stored in a flooded basement. I am quite sure that the problem here is in the manufacturing process somewhere. Since the problem seems confined to a particular kind of Kentmere paper it seems quite obvious that the paper is defective. Highly diluted developer should never be necessary. Dektol can be used full strength and has longer tray life at 1:1 than at the usually recommended 1:2. At 1:3 it begins to have problems with getting good Dmax and having limited capacity. This is probably the case for other paper developers at equivalent dilutions. Also, we have on this list a couple of people with good knowledge of photgraphic chemistry: one is Ryuji Suzuki and the other is Dave Valvo who was directly involved in Kodak's paper manufacturing. Either could answer the question about the effect of cadmium in emulsions and whether it should affect the type of developing agents which can be used sucessfully. Keep in mind that the market for photographic paper is very much smaller than it was only a decade ago. Kodak has stopped making B&W paper and Agfa is out of business altogether. Kodak had a very large and quite effective research laboratory which operated for generations (founded in 1912) and contributed tremendously to the theory and technology of photographic materials. I think Kodak was always ahead of the game although they suffered from slipping feet occasionally. Kodak had outstanding quality control and I think we have been spoiled by it. The ability to make a complex product like photographic sensitive materials consistently and in very large quantity is a an outstanding achievement but the very massiveness of the operation is a great factor in being able to do so, namely the money is there to justify the cost of research and QC. To a lesser extent AGFA also did research and had pretty good QC. Ilford was a much smaller company and, IMO, has had more problems with emulsions and coating than either Kodak or AGFA. About the only other big company in the photographic materials business now is Fuji. Fuji has an active research laboratory but limits its productl line. Evidently Fuji makes excellent B&W printing paper but sells it only in Japan. It would be interesting to hear from anyone on this list who has used it. Kentmere is an old but rather small company (compared to Kodak, AGFA, or Fuji) who, in the past, has specialized mostly in B&W photographic paper making much of it on a custom basis where it was marketed under the contractor's name. The company was recently bought out by Ilford, I don't have any inside information about what changes, if any, that has made in Kentmere's operations. I've used quite a bit of Kentmere paper in the past, both with their own brand and as custom paper (Freestyle). Its OK but not up to the quality of Fuji or Kodak. For one thing no other paper can touch the old Kodak products for the quality of the support, Ilford's is quite good but IMO both AGFA and Kentmere have had problems with curling right out of the box. AGFA paper also suffered from occasional frilling at the edges suggesting that there was a substrate problem. I am talking of course of fiber paper although I've had curling Kentmere RC paper. In any case, I would persist in calling Ilford about this. They own Kentmere now and, unless this is _very_ old stock they should take some responsibility about tracking down the problem. From the comments on the web site referred to in another post this is not a singular problem and could indicate something seriously wrong in Kentmere's emulsion making or coating line. 

--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx 
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your 
account (the same e-mail address and password you set-up when you subscribed,) 
and unsubscribe from there.

Other related posts: