Yellow Steel Hull Barrier Coat

[Gnarl]

Hello,

I have a steel sailboat hull that I'm working on and had a question.

Note that I am in the process of taking everything down to the metal and repainting as I was unsure if the correct paints were used to protect the steel. However on the outside I found a yellow barrier coat under the top coat that seems to be in good shape, light sandblasting does not penetrate it.

I was going to use a metal etch primer, a tie-coat primer and an epoxy, but if the yellow stuff (zinc chromate?) looks pretty good, maybe I don't need to take it down to the metal.

Note that I had a survey and it appeared as if there was rust/ tiny bubbles of corrosion or something under the paint but to me it looks more like the top coat is getting messed up.

Your advice or input would be appreciated. Thanks!

[S/V Alchemy]

It could be zinc chromate or it could be a two-part epoxy barrier coat. Best to find out before you blast it off.

If you are going to the trouble already, I would have the plate thicknesses sounded as well. If you have any loss in that area, better you replate now than after you paint.

[minaret]

Very likely zinc chromate. ZC is a very characteristic sort of greenish-yellow. Can't be mistaken if you know what you're looking at. If it's still good don't take it off.