Hello All, I finally acquired a used densiometer (Tobias Model TBX). It seems to respond to changes in density but I would like to check it's linearity across it's range. Would a calibrated step gauge (Kodak, Stouffer) be the thing to get? It has two internal adjustments and the exterior "zero" adjustment. I assume the internal adjustments are for calibrating the linearity.. If anyone has any information or suggestions on the unit I would appreciate it. I hope this topic is in the correct area... Thanks, John.