I have a hunter 23.5 with some old bottom paint from previous owner. The black stuff appears ablative since it chalks my hand somewhat. But then there is this strange gold coating/staining under the black (see pic). I couldn't get it off with paint stripper, acid wash, rust remover, or acetone. Would like to get everything off without sanding. Any guesses as to what it is?
Mystery bottom paint coating
- Thread starter bigchief
- Start date
-
- Tags
- bottom paint
It looks like staining from the bottom paint. Some of the coloring agents may have bleed into the porous gelcoat and stained it.
The pinholes and pockmarks in the gelcoat are interesting. I wonder what happened, I doubt the hull left the factory looking like that.
Try some mineral spirits or paint thinner. If that doesn't work try BarKeepers Friend. This is a mild cleanser with an oxalic acid bleaching agent.
Finally, try wet sanding, start with 400 grit and work your way up.
The pinholes and pockmarks in the gelcoat are interesting. I wonder what happened, I doubt the hull left the factory looking like that.
Try some mineral spirits or paint thinner. If that doesn't work try BarKeepers Friend. This is a mild cleanser with an oxalic acid bleaching agent.
Finally, try wet sanding, start with 400 grit and work your way up.
If it's that resistive to solvents and other etceteras, maybe it's a good base for your bottom coat. Ablative ? If the gold coloured material does cause problems, removing ablative is a liveable problem unlike removing a hard bottom paint.
IMO, I'd accept it and paint over it. Also to consider, is the boat trailered ? Even less demanding surroundings.
While it does look like gold fiberglass epoxy, it is on top of the white gel coat, not under.Looks like fiberglass under gel coat, under black bottom paint!
Good thing the stripper, etc, didn't take it off.
I've seen that on my 79 H30C.
Looking at the photo again, it may be residue from a coal tar epoxy barrier coat. This was popular in the 80s and early 90s, VC Tar was used with VC-17 going over it.
Over time the tar products dried out and began to wear off. I don't believe VCTar is available any more.
Over time the tar products dried out and began to wear off. I don't believe VCTar is available any more.
Assuming I'm correct, the solution is to ignore it. Clean it up all the remaining black tar with 80 grit sandpaper and then apply a new barrier coat according to the manufacturers instructions. And then enjoy happy days of sailing.We Have a Winner!
I'll pursue this Coal Tar barrier coating idea. Looks like VC Tar2 epoxy primer is still sold today and so is Seahawk 1255 Black Barrier Coal Tar. I'll see if they have any tips for removal or over coating.
When I bought the boat I thought it was just ablative antifouling because of the chalking on my hand, but the stuff would never wear off and really doesn't slime up. Seems like a durable long lasting barrier coating.
When I bought the boat I thought it was just ablative antifouling because of the chalking on my hand, but the stuff would never wear off and really doesn't slime up. Seems like a durable long lasting barrier coating.