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Discussion in 'B&W: Film, Paper, Chemistry' started by aoresteen, Jan 25, 2014.
Is Kodak OA filter ok for use with Ilford Multigrade IV papers ?
Probably not a good idea. OA is a greenish-yellow, which probably passes too much green light (Multigrade papers are sensitive to blue and green light). See page 1 in the Ilford link below showing the spectral sensitivity of the paper, and the Kodak link below showing the spectral characteristics of safelight filters (in the graphs which follow the summary, OA is the first graph - and you can see that transmittance extends into the green wavelengths, well below the cut-off suggested by Ilford).
That being said, no safelight is 100% safe for indefinite amounts of exposure so the best thing to do - always - when you either try a different safelight filter or a new paper, is to conduct a proper safelight tests to determine your safe time. See Kodak and online resources for the proper safelight test procedure.
I think all the OA was good for was the old Velox paper. Useless nowadays.
In general you have more flexibility with graded papers because they are mostly blue-sensitive rather than blue and green sensitive. OA was also described as being ok with contact papers, but contact papers are typically significantly slower than enlarging papers. So all things considered, variable contrast enlarging papers require the most care in safelighting.
HERE IS a simple trick to check.take a new or usedCDorDVDwith you into the darkroom.hold it upand bend it slightlyuntil you see a reflection of your safelight in it. bend it enough to break the reflection into a rainbow pattern,similar to using a prism.now,the content of green and blue radiation becomes clearly visible.there should be very little of it,otherwise,switch to a deep red safelight;less comfortable for your eyes,but safer for the paper.
Kodak no. 13 filter is recommended for VC and panchromatic papers.
No. 0C or Ilford 902 http://www.ilfordphoto.com/Webfiles/20131161231142522.pdf
This is incorrect for VC papers: http://www.kodak.com/global/en/professional/support/techPubs/ti0845/ti0845.pdf (page 2)
Regardless, one should always properly test any safelight setup.
The info from Kodak Safelight Data sheet states differently. The #13 is for color negative papers, panchromatic black-and-white papers.
The OC is for contact and enlarging papers
Welcome Barry Kirsten to APUG!
While the OC (amber) filter may be safe for some papers, many prefer the extra safety of a no. 13 (dark amber), Ilford 902 (light brown) or 1A (red), for VC papers which are more susceptible to safelight fogging. Having said that, I used an OC for years without harm, but at a distance of at least 2 metres.
Thanks for the welcome, fotch.
Just for the record here is the Ilford recommendation from the Multigrade tech sheet:
MULTIGRADE IV FB Fiber can be used with most
common safelights for black and white papers. The
ILFORD safelights are especially recommended as
they generally allow darkrooms to be brighter, but
completely safe, for MULTIGRADE IV FB Fiber and
many black and white papers.
ILFORD safelights are the ILFORD SL1 darkroom
safelight or the ILFORD 902 (light brown) safelight
filter fitted in a darkroom lamp (for example, the
ILFORD DL10 or DL20). A 15W bulb is
recommended with these safelights.
For direct lighting, do not expose the paper to the
safelight for more than 4 minutes, and the distance
between the paper and the safelight should be a
minimum of 1.2m/4ft.
Other safelight filters can be used, for example,
the Kodak OC and the Agfa-Gevaert G7, or the
Philips PF710 safelamp."
...and the Kodak blurb on the OA and OC filters:
"OA Greenish yellow (for) Black-and-white contact and duplicating materials, projection films (i.e. NOT green-sensitive materials)
OC Light amber Contact and enlarging papers (this would work )
Red would work too, since it has even less green than the OC.
Here's a link to the Kodak tech pub: http://www.kodak.com/global/en/professional/support/techPubs/ti0845/ti0845.pdf
Whatever safelights you end up with, you need to test them for safety.