In case anyone is interested in seeing the difference between zinc phosphate and manganese phosphate, see below. This was done following Palmetto's instructions, part of which is to sandblast within an hour of application. Since I had three media grits I did one each for zinc and one each for manganese (total of 6). They were Garnet 110/120, Glass abrasive 75, and Glass bead 9. You shouldn't use glass bead because it polishes the surface and you want the surface to be rough so it will hold more oil. It is the oil that gives the rust protection, not the phosphates. Anyway, there was no discernable difference "visually" between the different grits on the test samples. Zinc is on the left and manganese on the right
