Question for Simon Galley (Ilford)???!!!
I recently developed a 35mm HP5 film, and found that messuring base + fog with my Heiland Splitgrade, this was 0,33. The develope before date is 2009. Admittingly this film has been through aerport control twice. Is this level of base + fog to high? I developed in Ilfotec HC 31+1 for 7 minutes. What level of base + fog should Ilford films give if fresh out of the factory? Should a question like this be asked on the Ilford website?
Jaap Jan Helder
04 June 2008
I have tested several Ilford films (in 35mm format) and the "film base + fog" has ranged from and optical density (OD) of 0.25 to 0.36. Your measured OD of 0.33 does not seem too high.
If you want to reduce the FB+F density as much as possible I recommend using fresh fix, and at lease 5 minutes in HCA. Both of these processes will strip as much of the "anti-halation" dyes as possible.
As for the "airport control", as long as the film is not placed in your "checked bags" you should be ok. Most films, except really fast films, will not see fogging until after 4 to 5 passes through the x-ray machine.
Examples of X-ray fog I've seen are usually pretty obvious exposed bands, not a subtle increase in base fog.
Developer choice can also affect base fog, and of course any light leaks in your film loading area will contribute to base fog, particularly with a fast film like HP5+. If light leaks are a factor, try loading in a changing bag or tent.
Originally Posted by naaldvoerder
so how did the negs print? surely that is the crucial question
I just checked some HP5+ negs (developed ID11 1+1) and I get ~ 0.33 (Vis) too. 120 and LF films have lower fb+f - possibly because they do not have the anti light-piping dyes in the substrate. So, all seems well at your end as far as fb+f goes.
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Jaap, back in October/November last year I shot HP5 that went through well over a dozen airport scans, in my carry-on luggage and the base fog is no different to my HP5 negs that haven't, the negatives all printed perfectly.
My Tmax 400 120 was scanned well over 18 times and that was all fine too. On some flights Chile-Peru for instance the hand luggage was scanned twice at Santiage airport and also on arrival at Lima.
I'm pretty sure that Ilford changed the emulsion (without saying) of the HP5+ (and Delta 3200). On my new 4x5" negatives (developped, as usual, in Moersch's Tanol), lots of black spots in the highlights!... Wolfgang thought it was because of the high alkalinity of Tanol (pH10,5 I think), but a friend of mine used D23 (+Borax) and had the same problem!
Base fog does seem high for a film manufactured in 2004 or 2005, although well within our manufacturing tolerances, as always with ILFORD Photo products you can return it to us and we will check it out.
We have not changed the emulsion on HP5+ or on DELTA 3200
Simon ILFORD photo / HARMAN technology Limited :
OK! How can you explane this problem?
I cannot till you return the negatives for examination by us: I have checked for any outstanding or known QC's ( Quality complaints ) regarding 'spots' : We have none whatsoever, on any film products. We would need to examine the negs ( usually done with our electron microscope ) and we will give you our analysis, we then check control samples and unexposed samples from the same parent roll your film ( we hold unexposed slittings for 6 years ) was finished from to see if we can replicate or find a similar issue to one you describe.
Simon. ILFORD Photo / HARMAN technology Limited :