Jeff, what I'd suggest doing, when you finally get all bits you need for your piezo system, is printing the 21x4 chart multiple times on a sheet using different curves and then measuring the linearity and seeing if any seem to work. As per my comment on Ilford papers in another thread, you may be surprised. In your efforts to fit as many 21x4 on the one page, just be careful not to print in the first or last 20mm of the page. And make sure to label them as you go along, as our old brains don't retain as much as they used to, i.e. even less.