Why VC17 is not good on outboards
Dissimilar metals react chemically to produce electric current when placed together in a conducting liquid. In the process, the metal that is more electrochemically active will corrode faster than if it were in the liquid by itself. It literally dissolves away. This is the principle behind sacrificial zinc anodes...zinc is more active than iron, so it dissolves and in doing so prevents the iron from rusting. However, zinc and iron are close to each other in terms of electrochemical potential, so the zinc dissolves quite slowly. The reaction is also slow because zinc anodes are compact, and have a low ratio of surface area to volume. The problem with VC17 is the copper powder. To begin with, copper and aluminum are about the most electrochemically dissimilar metals that are commonly available. Putting them together in a conducting liquid is already asking for trouble. To make matters worse, the copper is powdered which gives it an extremely large ratio of surface area to volume and makes it even more reactive. Finally it's painted right onto the aluminum. Can't get much closer than that. The end result is an environment that is extremely corrosive to the aluminum (not good). Now for the good news...VC17 can be wiped off with denatured alcohol in a paper towel or rag. Acetone will also do the trick, but it evaporates too quickly, is much more flammable and may take the paint off your outboard. Good luck. Peter H23 "Raven"
