Which epoxy resin?

sailingdog · Jun 21, 2009

I haven't use US Composites' epoxy. I have used the epoxy from Progressive Epoxy Polymers, and would highly recommend them. They're far less expensive than West Systems, and a no-blush epoxy as well.

Their website is located HERE.

RichH · Jun 21, 2009

Ditto on Progressive Epoxy Polymers (epoxyproducts.com), ... also RAKA (raka.com)

epoxyproducts also sell 'lining epoxies' for lining potable water tanks (FDA compliant for 'leachables' in potable water systems, etc.) and lining fuel tanks - TERRIBLE website but good products.

tsmwebb · Jun 21, 2009

What are you planning to make? I've used various off brand 5:1 epoxies for projects and never had any problems, but for critical work I always use West or Pro-set.

--Tom.

Ross · Jun 21, 2009

Do you need to use epoxy? Polyester resins are very good and adequate for most purposes and much quicker, sandable in an hour.

sailingdog · Jun 21, 2009

True, but for doing structural repairs or modifications, it really makes far more sense to use epoxy resins. Structural repairs and modifications need the greater secondary bonding characteristics of epoxy resins, since the bonding between the existing boat structure and the modification or repair will be relying on the adhesive (secondary) bonding characteristics for the strength.

Ross said:
Do you need to use epoxy? Polyester resins are very good and adequate for most purposes and much quicker, sandable in an hour.

Ross · Jun 21, 2009

I agree! The cost of materials per square foot is very small and the superior qualities of epoxy will largely compensate for less than ideal workmanship. Very well made polyester resin bonds on old fiberglass will defy a hammer and chisel for undoing a mistake. I have had to remove some of my work on occassion and chopping it out reduces the grinding time.
All of that said, when I installed my engine beds I used epoxy and my best practices. I didn't trust polyester resin to bond to black locust. A hammer and chisel attack on epoxy glued locust breaks the epoxy line and pulls very little wood.

sailingdog · Jun 21, 2009

Ross said:
I agree! The cost of materials per square foot is very small and the superior qualities of epoxy will largely compensate for less than ideal workmanship. Very well made polyester resin bonds on old fiberglass will defy a hammer and chisel for undoing a mistake. I have had to remove some of my work on occassion and chopping it out reduces the grinding time.
All of that said, when I installed my engine beds I used epoxy and my best practices. I didn't trust polyester resin to bond to black locust. A hammer and chisel attack on epoxy glued locust breaks the epoxy line and pulls very little wood.

Most adhesives have a fairly difficult time bonding well to the side grain of wood and will not pull much wood off when it shears. This is one major reason why Maine Sail calls the epoxy plug to balsa wood core bond weak in his drawings. Bonding to the end-grain is much more effective, since it is going to absorb the adhesive due to capiliary action.

Ross · Jun 21, 2009

sailingdog said:
Most adhesives have a fairly difficult time bonding well to the side grain of wood and will not pull much wood off when it shears. This is one major reason why Maine Sail calls the epoxy plug to balsa wood core bond weak in his drawings. Bonding to the end-grain is much more effective, since it is going to absorb the adhesive due to capiliary action.

That hasn't been my experience. Generally gluing end grain joints in cabinet work is avoided when posible. Gluing doug fir in a laminate will split the wood before the glue joint fails.

sailingdog · Jun 21, 2009

I'm not talking in wood-to-wood, but in wood-to-laminate situations. Wood to wood is a different use.

Ross said:
That hasn't been my experience. Generally gluing end grain joints in cabinet work is avoided when posible. Gluing doug fir in a laminate will split the wood before the glue joint fails.

sand sailor · Jun 21, 2009

ross

thats apples and oranges glue joints on cabinets are solid dense fibers in sturdy wood where fiberglass resin to balsa wood is not the structural member but a light weight filler or spacer material.when was the last time you built furniture out of balsa ??if they used doug fur or white oak instead of balsa the glue joint would be much better but the boat would sit alot lower in the water as well.
the glue joint is only as strong as the wood fiber and end grain balsa is much stronger than side grain but this is the only instance i could say that about

sailingdog · Jun 21, 2009

I would point out that the core material in a cored laminate is a structural part of the laminate. This is why they don't use something even lighter for the core material. The laminate places significant shear and tension forces on the balsa core.

sand sailor said:
thats apples and oranges glue joints on cabinets are solid dense fibers in sturdy wood where fiberglass resin to balsa wood is not the structural member but a light weight filler or spacer material.when was the last time you built furniture out of balsa ??if they used doug fur or white oak instead of balsa the glue joint would be much better but the boat would sit alot lower in the water as well.
the glue joint is only as strong as the wood fiber and end grain balsa is much stronger than side grain but this is the only instance i could say that about

druid · Jun 21, 2009

Ross said:
Do you need to use epoxy? Polyester resins are very good and adequate for most purposes and much quicker, sandable in an hour.

I did a test with polyester resin on plywood, using some 2in fg tape. Let the resin harden fully...and ripped the tape right off the plywood. Never considered poly for anything structural or glue-like after that. In fact, I'd rather use a decent waterproof glue (like PL Premium) than poly resin.

If you're in the Vancouver area, FibreTek makes it's own epoxy, called Aqua-set. Less expensive than West, and works great.

druid

Ross · Jun 21, 2009

druid said:
I did a test with polyester resin on plywood, using some 2in fg tape. Let the resin harden fully...and ripped the tape right off the plywood. Never considered poly for anything structural or glue-like after that. In fact, I'd rather use a decent waterproof glue (like PL Premium) than poly resin.

If you're in the Vancouver area, FibreTek makes it's own epoxy, called Aqua-set. Less expensive than West, and works great.

druid

Did you examine the fiberglass tape for wood fibers?. For cored structure I would not use any species of wood but would use either Corecell or Airex core. Both are more damage resistant than balsa core but also more expensive.

sand sailor · Jun 21, 2009

sailingdog said:
I would point out that the core material in a cored laminate is a structural part of the laminate. This is why they don't use something even lighter for the core material. The laminate places significant shear and tension forces on the balsa core.

yes but if you stress that cohesion to the point of distress thats where the soft spots come in and it delaminates thats why cored hulls dont last

Ross · Jun 22, 2009

sand sailor said:
yes but if you stress that cohesion to the point of distress thats where the soft spots come in and it delaminates thats why cored hulls dont last

not all cores are created equal. Balsa cores are very good until they get wet or are subject to impact damage. Then they fail with fractures internally. Corecell and Airex core are more damage tolerant and pound for pound are stronger and more durable than solid layup. Corecell and Airex core are not to be considered the same as klegecell/divinylcell which are not damage tolerant.

jibes138 · Jun 22, 2009

Check out the ISland PAcket Website for a core alternative

I'm not sure exatly what they use and it may be higher weight than some but it sounds like a mix of resin and lots of microballoons as the deck core material that would make it resistant to water intrusion and rot proof (if there is such a thing). It sounds like a proprietary mix so it is probably protected as IP by the company, but from reading about it a logical set of assumptions can be made as to ingredients. Seems like a good idea, any comments?

Ross · Jun 22, 2009

jibes138 said:
I'm not sure exatly what they use and it may be higher weight than some but it sounds like a mix of resin and lots of microballoons as the deck core material that would make it resistant to water intrusion and rot proof (if there is such a thing). It sounds like a proprietary mix so it is probably protected as IP by the company, but from reading about it a logical set of assumptions can be made as to ingredients. Seems like a good idea, any comments?

I seem to recall that you can purchase a cloth system that incorporates chopped strand mat, micro ballons and woven fabric in a single assembly. Builds alot of thickness in one pass.

Hermit Scott · Jun 22, 2009

Ross said:
not all cores are created equal. Balsa cores are very good until they get wet or are subject to impact damage. Then they fail with fractures internally. Corecell and Airex core are more damage tolerant and pound for pound are stronger and more durable than solid layup. Corecell and Airex core are not to be considered the same as klegecell/divinylcell which are not damage tolerant.

Ross- are you saying that a cored deck 1" thick is stronger than a solid fiberglass deck 1" thick?

Which epoxy resin?

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