Response to Making traditional internegatives.

The best book on the subject is Kodak's "Copying and Duplicating in B&W and Color", pub M-1. There are 2 methods used for this. One is to use the direct duplicating film, SO-132 Professional Duplicating Film. The other is to make the duplicate negative in two steps by first making an interpositive master and then contact printing that to get the working neg. In the Kodak book, they use both Kodak Commercial Film and Super-XX pan, as well as SO-132. All 3 of these are discontinued, SO-132 is on the chopping block now....you can probably still get it though. In 8x10, it will be close to $80+ for 25 sheets. It's about $45 a box for 25 sheets of 4x5.

Ilford Ortho Plus Copy Film is very similar to Kodak Commercial Film, so you can substitute this. From emails I've had with Kodak last year, they recommend TMX100 as the interpositive, and Tech Pan as the working negative, for 2 step duping. I have also had some emails with a lab that does large scale duplicating of historical negs & plates...they recommended Delta 100 Plus as the interpositive, and Ortho Plus as the dupe neg. I can send you the densitometer aim points if you're interested in them, otherwise here's a link to the vendor specs that the NARA uses:

http://www.nara.gov/arch/techinfo/dupspecs/blackandwhitenegs.html

The Kodak book is still the best on the subject, and will explain in detail both methods. I have used quite a bit of SO-132, and it can be a pain with certain types of negs--trying to match the tonal range of the original. It's slow, but it's an ortho film and you can use it under an enlarger much like paper...especially if you use a film holder or a black easel--flare can be a problem enlarging negs....you can tray process or do it in tanks in regular developers as well. ( I use DK50 1:1 in a tank) It's a positive material, so you have to think that way when you use it....more exposure equals a lighter neg and vice-versa. The film has to be processed exactly as Kodak indicates in the tech sheet...there were stability problems with earlier versions....Kodak recommends that you not use a hypo clearing agent with the film, rahter a full 30 minute wash. They also recommend either selenium or brown toning of the film as well. I have worked with older dupes made on the previous films like SO-015...they changed density & tone in storage....when I use SO-132 I do tone in selenium and go for the full washes....I'll let you know in 30 years how they've done....but most archives and historical institutions do this in 2 steps...the interpos becomes the master for safekeeping, the dupe negs becomes the working negs....you can dodge, burn etc on the interpos as well....

I have about a dozen boxes of SO-132, and still see 8x10 in stores...it never sells, it's sort of an oddball item. If you find some, you might want to stock up a little bit....good luck and:Opinions expressed in this message may not represent the policy of my agency

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