Is This A Barrier Coat?

[Kper]

I couldn't stop myself.
With dreams of stripping the black, ablative paint and switching to VC17 I took a putty knife to a small section of the hull to find out what little was there came off quite easily. My question is, what is this under the paint but over the gelcoat? Is this a barrier coat of some sort? It has a texture similar to rock coat on a car. I'm not educated at all in this area and was hoping somebody could shed some light on this for me.

The progress in the second photo took less than 5 minutes and the lower right portion of the third photo was an attempt with sand paper that only proved more burdensome with less results. I know the health risks involved with this stuff.

 

[Ken Cross]

It doesn't look like my barrier coat, but could it be coal tar epoxy? That could be considered a barrier coat.
Ken

 

[CloudDiver]

Whatever it may be, a new barrier coat would be a good idea and it should stick just fine as long as its not flaking off. If you continue your current process of scraping first to remove all the old loose bottom paint, then go ahead and sand to remove the rest using a respirator for protection. Also a good idea to hook up a shop vac to the sander if you have the port for it, even if you are working outside it reduced the risk to others and keeps the mess to a minimum. As long as you get a good sanding on that 'whatever it is' coating and there is no loose flaking then a new barrier coat like Interlux Interprotect 2000 will stick with a good mechanical bond. The only reason you would ever have to sand that coating off down to the gelcoat would be if it was really degraded and basically 'falling apart'. I don't think that is the case so no need to give yourself a bunch more work.

 

[Kper]

It seems to be in good condition but the more I walk by it the less I really want to invest in the time necessary to strip the paint. Besides, my shoulder keeps telling me to let it go and slap more ablative on it while my perfectionism tells me to strip away.

Thanks for the replies.

 

[Tim R.]

Do not try to coat over it until you know exactly what it is. If it is that battleship gray looking stuff it could be interlux 2000. After 2000 hardens it requires sanding to apply new paint.

 

[Kper]

Tim, I believe what you describe as battleship grey, most pronounced in the first photo, is old bottom paint. Rubbing it leaves a black residue on the fingers. The brown under what I would consider grey is about a full 1/32" thick. Much thicker than any paint or epoxy coating that I've seen.

 

[Joan123]

I took my hull down to gel coat and am going to apply
3 coats of barrier coat. Then I'll put a red coat of bottom
paint then a blue so when I am cleaning the bottom
and I get to red I'll know I need to paint again.