Re: Calibrating & Re-Certifying X-Rite Densitometers
>will the white patch on the t card from printtools.org be ok to calibrate absoloute zero when reading LAB refs.
Are you talking about measureing Lab or density and relative to the paper (removing paper white) or absolute white (measureing with paper included)? For Lab measurements, you would not want to calibrate the spectro relative to the paper (remove paper white). For one, most spectros probably won't allow this, and second, your readings would surely be skewed from the Lab benchmarks provided with the card. Lab readings relative to paper are not easily calculated as paper is a large influencing factor in color.
Therefore, purchasing the T-Ref card for verifying Lab measurements isn't advisable as 1) there are no provided Lab values with the T-Ref card, just density (absolute density at that, that is, including paper), and 2) since there are no Lab values, there is no tracebility back to an official standard (ANSI) for verification.