Digital BW, The Print

OBAs absorb UV and re-emit as bluish visible light.  So, to see if there are
OBAs, look at the paper under a black light.  The OBAs glow, the natural
paper does not.

Paul
www.PaulRoark.com 


> -----Original Message-----
> From: DigitalBlackandWhiteThePrint@yahoogroups.com
> [mailto:DigitalBlackandWhiteThePrint@yahoogroups.com] On Behalf Of
> dfaprinting
> Sent: Tuesday, June 14, 2005 4:14 PM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: [Digital BW] Re: Paper Trends - Some Observations
> 
> Regarding OBA detection:
> 
> There are a couple of ways to check if you have a colorimeter or
> better a spectrophotometer. Simplest is to measure the L*a*b* of the
> paper white and see if it tends towards blue. Second is to take a
> spectral based reading of paper white, and then make a graph of the
> values (programs like Xrite's ColorshopX makes this easy). An example
> from Colorshop X in the color scratchpad "tool" looks like this:
> http://img.photobucket.com/albums/v329/Greg_E/Intelicoat17mil.jpg
> 
> You'll notice the hump at the blue end of the spectrum which
> generally indicates that there is OBA present. The sample is the
> Intelicoat 17 mil cotton/poly canvas material. Papers like Enhanced
> matte have a huge hump at the blue end.
> 
> And yes ColorshopX works with the i1 spectro, as well as many Xrite
> measurement tools. The above was made with an i1 pro "new" generation
> of spectro. Also works with the old DTP22 Digital Swatchbook that you
> can often find on ebay for a few hundred dollars. Complete overhaul
> of a real DTP22 is somewhere around $400, but Xrite won't work on
> the "generic" OEM type Swatchbook, so be aware when you are buying.
> 
> 
> 
> 
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