Epoxy Resin Quality

[Gunni]

Marine epoxy barrier coats have been in use for 30 years as a proven treatment for hull blistering and we have known for years what causes blistering - the permeability of gelcoat /polyester, hydrolyzation of polyester resins used in hull laminates; and the hydroscopic nature of glycols in polyester resins drawing moisture into the laminate. And no, the manufacturer (who happens to be my manufacturer - Beneteau) does not void a warranty for sanding their gelcoat to put on a barrier coat. And no, all epoxy resins are not the same.

So to the original poster, choose an epoxy formulated for marine application, not by the resin/hardener mix ratio. I like WEST, MAS, and RAKA, ask a marine tradesman what they recommend. Make sure you get the specified epoxy film thickness. It is a pretty fool-proof DIY product, with lots of uses.

 

[centerline]

Epoxy is NOT water proof. Where have you found any study of how effective a barrier coat is or even what causes a blister . At least one boat manufacture will void its warr. if their gellcoat is sanded to put on a barrier coat. I would agree that epoxy is a product that has its place but is far and away overused. Too much armchair boating.

all epoxies are NOT the same... not all the ingredients that can go into making an "epoxy" are the same ingredients used by all manufactures.
whatever ingredients that were combined to create the formulation in the container may now fall within the description of an epoxy, but that does not tell you if it was formulated as a waterproof epoxy.
some are, and some are NOT.....

as for studies of how effective barrier coats are, there are a couple that are very comprehensive and detailed studies about blisters, their cause, their repair, and the most effective way to lessen the chance that they will return.... and it also explains how a barrier coat on the outside of the boat may do very little good if the inside of the hull is continually wet from sweat/condensate or submersion, as the water can get into the polyester from the reverse side and still cause blistering.

and of course a boat manufacture may choose to void its warranty if is intended design is tampered with.... what manufacture anywhere, for any type of equipment or vehicle will let you tamper with (and possibly screw up) their design and still honor the warranty they offer for THEIR product? and if its still under warrenty and it fails, let the manufacture fix it.

but after the warrenty gives out, and the boat gets old, and blisters appear, a barrier coat can help, but in some cases and for some boats, it isnt worth it.... nor is a barrier coat a guaranteed lifetime cure.

and I also think epoxy is an over used product, when for most repairs, polyester is the perfect choice... it it almost always the craftsman's workmanship that is inadequate...

 

[Charlie Jones s/v Tehani]

Epoxy is NOT water proof. Where have you found any study of how effective a barrier coat is or even what causes a blister . At least one boat manufacture will void its warr. if their gellcoat is sanded to put on a barrier coat. I would agree that epoxy is a product that has its place but is far and away overused. Too much armchair boating.

Having now built about 15 wood/epoxy boats, plus several water and diesel tanks using epoxied plywood. I must disagree.
One of those has been afloat since 1982 with no problems whatsoever.
And my own boat has an epoxy barrier coat which has totally stopped the blistering she had when I got her.
NEWLY built fiberglass boats are using a completely different polyester resin than was used years ago, when the blistering first reared it's head. Yes, properly applied, and cured epoxy is waterproof,

 

[MrBill_FLL]

FWIW, when I mix epoxy, I measure the amounts into a 'dixie' cup, and mark the edge with a marker. (using water), to get the amounts I want. ie, 1:5 1 oz water in a cup and mark. 5 oz of water in a 2nd cup and mark.

I bought the west system pumps, but hate to leave the pumps attached (storage issues).
I also think west systems is over priced for most jobs.

 

[mm2347]

The point I want to make is that epoxy has its place but is often used as an universal glue or resin. As with any universal item there are often compromises. For example: the people at WEST have put together systems that will work but the cost will often be high. As plywood saturating resin or a laminating resins goes there are many but the user will have to most often will have to do their home work. One of the better wood glues markets it product to large industrys and dosnt West does it for you and you will pay for that and they only give their attributes.

 

[mm2347]

Sorry everyone. My computer or hookup is acting up.