I have been using Smart-Tech1st's solvent based system for a couple of years now. Haven't switched to the WB one as I have plenty of material left and I believe I can still get refills?For darker colours, I can get a very acceptable repair, but it takes time - silvers suffer the usual problem of the flakes sinking and being too dark although I do lighten with a bit of white pearl.I charge for touch-ins but make it clear that it is simply protecting the area from corrosion. I make sure the customer's expectations are set very low and try to over-deliver. I only do touch-ins as part of other work. Why shouldn't I charge? It's my time and the customer knows exactly what to expect. They wouldn't pay if they weren't happy.CheersDavid