I'm looking for a marker with opaque ink that is waterproof and permanent; I want to use it on black plastic that is likely to come into contact with a lot of water. The tip needs to be reasonably thick and I'd prefer a bullet tip to a chisel tip. I've been looking at different kinds of pens but I'm having trouble working out what's best. Posca Acrylic Paint Markers look like they could be good, but one site I visited said that whilst they are considered 'permanent' the ink washes off plastic with detergent and water. The Artline Paint Marker (409 XF) looks like it could work; it is advertised as good for "any surface indoors or out" but I haven't seen anything saying just how waterproof they are. The Pilot Paint Marker SC-PM looks good too; it's billed as "permanent and waterproof on most non-absorbent surfaces", but obviously most is not all, I'm guessing that it would be worst on polished metal and would probably adhere to plastic just fine, but hey, I have no idea. If anyone has used these before and can tell me if they're suitable, that would be great. Suggestions for other pens would be most appreciated as well. I'm leaning towards the Pilot marker at the moment but I really have no idea.