I bought a set of used KK trim tabs that are in very nice shape however have some barnicle build up (here and there). I scraped most of what I could get to however they leave a white star/shell shape blem in the original paint or powder coat. The only thing I have tried so far is hot water with a very mild abraisive pad and soap. It didn't really touch it. Still have the white marks. I am probably being overly fussy but thought I would check anyway.

Thanks,
John

My whole hull was covered in them. I used hydrochloric acid. Took care of them in no time. I bought the acid from the marina labeled as a product called on-off. I was using a garden sprayer to apply the acid, so I am sure some got on my outdrive. After rinsing the boat down I didn't notice any damage to the paint on the drive. So it looks like the acid attacked the barnicle but didn't hurt the paint.

I'll give that a shot. I really appreciate the help. I see your from MI. I was thinking this was more of a salt water thing. Not sure. They almost look like zebra muscles.

pick up some muratic acid at home depot use a prayer.

Agreed, except I would use a sprayer instead of a prayer

and DO NOT let the stuff get to your eyes !!!!! you can end up at the emergency room....happened to a friend of mine..stuff is rough

LOL. yes use a sprayer

Yeah I am in Michigan, but my boat was left in saltwater.... I just bought it from out of state. I have heard zebra muscles are pretty much the fresh water equivelant. I tried Muriatic acid first. It didn't seem to work much. THe hydrochloric in the "on-off hull cleaner" worked 100 times better.