There are a few ways to determine if brighteners exist in the paper. A
black light is a quick down and dirty meathod. If using this method
also measure your target. Many press stocks also have brighteners and
it is best to find a media with similar values. I also use a large 82
MM camera UV filter below the Black light to see the difference.
The Tappi brightness method measures the reflectance of a substrate at
457nm. (The blue range.) This method was originally used to measure the
pulp consistency in paper. There is also an ISO method that does not
correlate with a simple formula like Celsius and Fahrenheit.
ProfileMaker will suggest to correct if it determines anything with
more than -3b value (lab).
I have also seen papers with a -3.5b not glow under a K-light, but a
paper with just a -3b really glow. The only difference is the paper
that glowed had a really high L* like 97 of 98. Maybe an expert can
chime in on this one. These were all measured with a non-uv device.
Lastly, Many big proofing manufacturers still use FWA's or OBA's in
there medias. This can lead to many extra edits while profiling...even
though the Delta E numbers may look good. Brighteners can be unstable
and can lead to media inconsistencies.
Anyhow, my two cents...
Troy Buccini
email@hidden
On May 27, 2005, at 2:37 PM, Steve Upton wrote:
At 2:44 PM -0400 5/27/05, Nicholas Androulidakis wrote:
Is there a list available somewhere of papers that do or don't use
optical brighteners?
For example a listing that might say whether Epson's Professional
Semimatte or Enhanced Matte or Han. Photo Rag use optical
brighteners?
not that I have seen.
There is a fairly simple number though - 95%
that's what percentage I would estimate contain some amount of
brighteners
Regards,
Steve
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o Steve Upton CHROMiX www.chromix.com
o (hueman) 866.CHROMiX
o email@hidden 206.985.6837
o ColorGear ColorThink ColorValet ColorSmarts ProfileCentral
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