Thanks, Jan!

Do a seach on "Shot Glass Method" which allows you to use an OTO test kit to get an approximation for higher FC levels than are on the scale.

You may also want to search on OTO colors above 5ppm--Ben had done some work on colors for much higher OTO levels.

Meanwhile, over at TFP, they are debating some of that and there's an easy-to-find discussion with the color scales that Ben had done. Maybe we can get some cross-pollination....