Bleaching the film base

[mikael1]

Is there a way to (at least partially) bleach the film base? I'm

experimenting with photographing patterns, architecture with very high

contrast. I'm developing Tri-X in Neutol paper developer to get really

high contrast and would like to drumscan the negs. Having almost only

B&W negs would be preferable in the scanning process, so I'm

interested in finding a way to bleach the film base witout removing

the emulsion. Anybody had any success? I've had the impression that

aerial B&W film is almost transparent. Is this right?

[ann_clancy3]

If you are looking for a clear film base, try "Blue Fire Police" film at the Frugal Photograper.

[mikael1]

Looks really interesting! Thanks! The problem is I'm not situated in the US, the toll fees I have to pay in Sweden are horrible. Add to that the shipping.

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This whole thing is quite experimental and it doesn't have to produce top notch results (ie. fine grain). If anyone has a simpler sollution, please drop a line!

[garrylewis747]

I believe I've read that Macco PO-100 orthochromatic film has a

clear base and is available in europe.

[silent1]

You might look for a local supplier of Agfa Copex Rapid, the stock used to spool Bluefire Police. If you can find it in 35 mm (probably in bulk rolls of 30 meters or larger), you can either develop in one of the SPUR developers (Nanospeed would be a good choice, probably, for EI something like 40) or in Neofin Doku or Dokuspeed, the latter at least should be good for EI 80. Another option would be to find the recipe for H&W Control that's floating on the 'net and mix it yourself from standard photo chemicals (phenidone, hydroquinone, etc.).

 

If you like high contrast, you might try a diluted standard developer; I've seen good pictorial results from microfilm in D-76 1:7, and I'd guess 1:5 or 1:3 would give contrast similar to what you're getting with Tri-X in Neutol, but of course with vastly finer grain and lower speed. Some people even develop microfilm in Rodinal at high dilutions; for high contrast you might find you like 1:100 or even 1:50.

 

Any microfilm stock you find (Kodak, Fuji, or Agfa) will have a completely clear base -- beware, the clear base will make you think your negatives are either underexposed or underdeveloped; wait to see scans or prints before making a decision about EI or developing times/dilutions.

[ann_clancy3]

I think there is also a German film, not sure of the spelling but is similar to "blue". Gibite or something along that line, sorry to be so vague. Too much fixer on the brain.

[robert_davis2]

Gigabit? Is that it?

 

Does freestyle still sell 35mm lith film? Wouldn't that be the best choice?

[garrylewis747]

Don't forget he said he was in Sweden. So he needs something available from a european market.

[robert_davis2]

http://www.mahn.net/Frameset.htm

 

Click on films. Quite a few have clear bases. The lith film seems to only come in sheet size. But should be able to get high contrast out of the 35mm films they sell.

[ann_clancy3]

I found it and it is Gigabitfilm, try this site;

http://www.fotoimpax.de/index.html

[bruce watson]

To answer the question, I don't know of, haven't read about any, nor have I heard of anyone bleaching the film base. I don't think you can make the film base clear, if that is your aim. It is hazy on purpose.

 

I do my own drum scans of Tri-X, and I can tell you from experience that it drum scans just beautifully, with it's hazy film base. With a drum scanner, you can set your shadow and highlight points manually (all the software with which I'm familiar anyway), so you basically scan "above" the film base + fog.

 

Before you spend too much time pursuing bleaching, try scanning without bleaching. If it's not what you want, you can always modify the negative and scan it again. If it does work for you, you've saved a lot of time and trouble.

[patrick_gainer]

Line art printers IIRC use a cutting ferricyanide bleach to clear the base of the litho film of development fog. Tri-X and even more so HP5+ have dyed bases that cannot be cleared. Even if you strip the emulsion with full strength chlorine laundry bleach, the gray remains. There should be no problem for the scanner to remove the slight amount of gray, as another poster said. Anything I can do, they can do better.

[mikael1]

I do my own drum scans (Scanmate 5000) of Tri-X (souped in Diafine) and I can't say I'm too content (also I do APX 100). For lineart and stuff that should basically only contain black and white I'm sure it's not a big problem to crank up the contrast. Other pictures though... Seems to have something to do with the compression of the tonal range. Everything seems to go in a range from black to gray, to gray, a bit bit darker gray. But the highlights are so well controlled they're not there (and no, the levels and curves are not always a cure & trust me I think I know these tools). I know, Diafine isn't probably the best developer for scanning as it is known to be very good at blocking high-lights.

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Well, I'm on another topic now. :) Have to thank you all for the info you've provided me with! I may try some of the films tips posted here.

[roger krueger]

Sounds like Kodak Technical Pan in Dektol (or really just about any developer EXCEPT

Technidol) is what you're looking for--nearly clear base, massive contrast. As an added

bonus you get tiny grain and great resolving power.

[conrad_hoffman]

I'm confused. The dyed film base acts just like a neutral density filter, or even changing the intensity of the light source used for printing/scanning. It has no effect on anything, since it adds to all areas by the same amount. What it does do is prevent light piping through the base, something important on fast films. If you want high contrast, use a copy film and develop to a high contrast. Tech Pan and D19, or one of the other combinations mentioned. Actually, any medium or slow film can probably give you more than enough contrast for any possible need, just by exposing carefully and increasing the development by 20-50%.

[test11664875106]

<P>If you want scans, and if you want high contrast, and you're experimenting then you can't be wrong giving at least a try to Agfa Scala. It's a b&w slide film. It can be very soft like <A HREF="http://www.photo.net/photo/315656">here</A>, or it can be extremely contrast like <A HREF="http://www.photo.net/photo/311667">here</A> (and even higher if you use it at E.I.1600 and push process, it will retain small grain though). In my experiments if you shoot it at low contrast you can get subtle details as low as shadows at -2 stop and as high as highlights at +2.5 stop from the meter reading, but you have to see it with your local Agfa Scala lab (yes, you have to hand it over to <A HREF="http://www.agfa.com/photo/products/film/professional/bwrevfilm/scalalabs/">special lab</A>, it's not E6 process) - I had slightly different results with lab in Copenhagen and in Paris.

 

<P>Have a look on Agfa web site for <A HREF="http://www.agfa.com/photo/products/film/professional/bwrevfilm/">general info</A> and <A HREF="http://www.agfa.com/photo/products/pdf/F-PF-E4_en.pdf">data sheet</A>.

[test11664875106]

<P>Also, in his last post Conrad mentions one part of very good point - film base won't be noticed if you print through. But if you remove it and ever want to print your negative it won't fit into exposure scale of normal paper, you'll have to print on softest paper or with softest VC-filter. On the other hand if you do scans, you need that extra contrast range. (See my comments on post about "Developing for scanning" few posts before your question).

 

<P>I just recalled that Ilford has a <A HREF="http://www.ilford.com/html/us_english/pdf/reversal_web.pdf">reciepy</A> for reversal processing of B&W films. This involves bleaching in high-energy sulphuric acid so it should clean up the base nearly to zero. (Be extremely careful with high-concentrated sulphuric acid - it can also disolve your skin!). Though I have no possibility to try this process as I can't get hold of sulphuric acid.