Bottom Crazing

[Jfwtc]

I have removed all the bottom paint. The bottom was than sanded with 80 grit. The hull laminate is very dry, tested by meter. There is no blistering or pox. The gelcoat is solid and non-flaking, but lots of crazing. At forty three years old I have no concern that blistering or absorption will start now, but I don?t want the crazing to print thru new coatings.
If I use the West System bottom blister process followed with Interlux 2000 will this prevent the crazing from printing thru new coatings?
All suggestions are welcome.

[radicalcy]

Are we talking about the keel and lower hull? What difference does it make if it prints thru? Its not going to affect the bottom paint. Unless you take the finish down to bare glass, barrier coating can cause more problems than it solves. And as you said, the boat is 43 years old. If it lasts another 43 years as is, you've done your job.

[Tim]

I agree. I can see no reason to spend large amounts of time prepping the bottom to prevent print-through. It's the bottom, and the heay, thick paints tend to hid the cracking alone, if it matters.

I would also avoid the use of any barrier-coating products, but that's just my opinion. I have written extensively on this in the past here on the forum (locatable with the search function), so I won't repeat my reasoning here.

If the crazing extends into your topsides, you may have a more legitimate reason to be concerned with print-through. Addressing this sort of issue is very challenging. Depending on the results you want, you could strip the old gelcoat and any cracked laminate (a huge job, to say the least), or consider sheathing the entire hull with a thin layer of fiberglass in the hopes of stabilizing the existing crazing and hiding it, the way we did on Dasein over the winter.

There are no guarantees that either of these time-consuming methods will work over the long haul, but they seem to be the only viable options. No primer or paint will sufficiently fill these cracks over the long term, no matter how well it might cover initially. Each case is, of course, different, but in general such crazing is a challenge to hide.

[dasein668]

or consider sheathing the entire hull with a thin layer of fiberglass in the hopes of stabilizing the existing crazing and hiding it, the way we did on Dasein over the winter.

Also a huge job, to say the least!