I just made a hickspodisc with some black posterboard and 2 coffee filters to fit in my Cokin P setup.
granted I don't have a reliable graycard, but I went and took some test shots to compare the levels in the histogram.
I went to a room lit by fluorescents, and shot and used a custom white balance, followed by AWB and then "fluorescent"
it seems that the whites were blown out pretty bad with the coffee filters, but the color temp seemed very close to the "fluorescent" which was not blown out. both of these were better than AWB, but not much (probably an easy lighting situation for the AWB)
any thoughts on the blown out highlights?
Brian