400hrs only between repaint!!!??? We operated an eng machine around 120 hrs a month, coastal and in plenty of rain and we would get over 1000hrs before even a slight touch up was required! You don't need to be over anal on this, just don't let them erode to the bond line. Use the Robinson tool to put a felt mark on the blade with the location of the bond line and monitor the erosion. If its starting to come off in chunks then take some sandpaper and feather the edge of the paint down to the stainless so that the wind/water/dirt etc can't get under the paint and pull chunks off.