Regular epoxy for barrier coat?

[jimbunyard]

Originally Posted by jimbunyard

I've also used West, System Three, Mas, Resin Research and a variety of off brand epoxies, and I can assure you West and System Three are definitely not impermeable to water. I've only used Mas on dance floors and table tops, so can't tell you about it, and the story is still out on Resin Research because I've not yet done any work on previously coated surfaces to find out. Off brand epoxies don't get used in critical applications.

Within any 'class' of resins there are different formulations, any of which will affect the properties of the specific resin.

Forgot to add that my comment about West and System Three epoxies is based on using products from at least 3 years ago. They may have changed their formulations, thereby modifying the physical properties of those products....

Obviously, it's always best for one to know what the specific properties of the actual product one is planning on using are, when evaluating them for their suitability for an application.

There may also be some issue I've not heard of using vinylester as a seal coat that I'm unaware of, and would appreciate if anyone who knows of any would speak up...

[HappyMdRSailor]

If it were me, I'd be using epoxy base coats of about 3, then epoxy fair, after these, 3 2000E coats, and then AF...

[CuChulainn]

Having done an extensive blister repair and barrier coat on An '84 San Juan 28, I used West epoxy for the blister repairs using their high density, low density and colloidal silica fillers (depending on how much damage was in each blister). Plus fibreglass cloth in some cases. When they were all fixed and faired, I used Interlux Interprotect 2000E for the REQUIRED 5 coats. I considered West epoxy with the barrier additive but for ease of use for a big job Interprotect 2000e was much easier to do, you just mix the two cans together and away you go. I had the boat for five years after that and had no reoccurrence of blisters. I now have an '86 C&C 33 that had an extensive bottom peel, epoxy re-glassing and five coats of Interprotect, no issues to date.
If it is a small repair, I'd go with West epoxy + their additive ( 422? ). If it is a whole bottom, Interprotect 2000e, just for ease of use if nothing else. They are both excellent products.

[Stumble]

Originally Posted by Reefmagnet

I believe I've read in the past that vinylester won't require a barrier coat which indicates it's resistance to osmosis problems. I've not heard that vinylester can be used for barrier coats though.

Sent from my SGP521 using Cruisers Sailing Forum mobile app

This is generally true... BUT.

Even if the hull material (vinylester or epoxy) is impervious (or generally so) to water, one of the advantages of a barrier coat is that it ensures any small pores in the laminate layers are filled, and any stray fibers are wetted down and sealed. Barrier coats are also tinted differently than laminate epoxy which provides a clear visual guide when sanding bottom paint off years down the road when you have gone deep enough.