Epoxy or Resorcinol-based glue

[bigdawg10132009]

just a question......
can you use resorcinol based glue in lieu of epoxy in the application of fiberglass?????? i understand it is a very strong glue and epoxy is a type of glue correct? so it would seem one could use the glue as such eh????

[PAR]

In a word, No for several reasons. It will stick to cured 'glass, but it will not wet out fabrics, making it useless in this regard. If you just want to glue something, there are a lot easier to use products then resorcinol. If you want to apply 'glass fabrics, you'll need a resin system designed to do the deed.

[keith66]

Resorcinol resin was used in a proprietary system called Cascover. it was intended for sheathing the bottoms of wooden boats, primarily intended for worm protection?
The system enjoyed a degree of success in the UK at least, it was not available as a DIY option and was professionally applied. It used a fine nylon scrim cloth and had a pretty good reputation.
It became obsolete with the advent of easier to use epoxies.

[scotch&water]

If you are repairing a fiberglass boat, say a 21 cuddy go to polyester resin,the fiberglass mat and woven fiberglass has a binder coating to help polyester resins incapsulate the fibers. When lamenatin fiberglass get your self a roller made for gettig all the air out, no white spots.

Do NOT use poly resin, use Epoxy! Polyester resin is by no means a repair resin, it does not stick well to anything (except your skin and trousers), not even to the old poly.

[Jimbo1490]

Fiberglass cloth intended for composite production has a textile 'finish' of either Volan or Silane. Without getting too deep into what these are and why you need them in the first place, just know that neither is compatible with resorcinol glue, so the bond between the glass and the glue will not be permanent. Note that the system mentioned above that used resorcinol glue also used a proprietary fabric.

Jimbo

[PAR]

I know of a few hulls sheathed with Cascover and remember reading about it years ago. It wasn't an easy material to apply, certainly not novice friendly. It's repairs easily with epoxy and modern fabrics. Considering the pressures and fitting precision necessary for good wood to wood bonds with resorcinol, it seems an unlikely prospect.

[scotch&water]

Steamer, I begto differ with your opinion of Polyester resin, a good laminating resin will bond to a well prepaird surfaceby grinding with min. 80 grid disk, thicknes out times 12 it works every time. Think of all the Boats constructed with polyester resin. Now some hulls put Vinyl ester resin in to the outer layers to prevent osmosis and blisters but repairs can still bond with Polyester or Vinyl ester. Cost is over 50% more for Epoxy over Polyester in most catalogs, when refinishig Gel coat can be sprayed over the repair sanded and buffed, the blendig is great. Fritz

[wardd]

back in the day i worked on army helicopters such as the ch-47 and often the fiberglass parts would have dissolved resin from the hydraulic fluids. i believe polyester was used

[quote=scotch&water;292426]

Steamer, I begto differ with your opinion of Polyester resin, a good laminating resin will bond to a well prepaird surfaceby grinding with min. 80 grid disk, thicknes out times 12 it works every time.

Well, it does NOT, Polyester resin sticks to nothing (at least not good), except uncured polyester resin. But of course you´re free to have your own opinion.

Think of all the Boats constructed with polyester resin.

A newbuild layup is a completely different world as a repair right?

Regards
Richard

[Ilan Voyager]

I agree with you Apex...There is a rage to use a polyester outside its fields: laminating new hulls, fresh on fresh...

About sanding deeply until fiberglass and thus having the hope of a mechanical key between the old GRP and the new polyester, I'm too old for that ****...It's so simple to make a light sand blasting and to glue with a epoxy resin that finally it's cheaper than using polyester. Much less work, less resin to use, less messy also and better quality and reliability.

There is some urban legend about epoxy that we have all these questions about epoxy? polyester if far more dangerous with the styrene you breathe, plus heavy metal (cobalt), plus highly corrosive stuff (peroxide), plus solvents.

Resorcinol, which is a glue and nothing more, is more toxic than epoxy, stains every thing, it's not tolerant, needs high pressure and perfect joints. Lone advantage resist to swell stresses of laminated wood. I know the Cascover, gosh!!!! very difficult stuff to use. It was good in 1968, we are 41 years later...

[Jimbo1490]

We all need to keep in mind the difference between ADHESION and COHESION.

Cohesion is a noun that describes the ability of a material to hang together when stressed by a force tending to pull it apart.

Adhesion is a noun that describes the ability of a material to remain in contact with another substance when stressed by a force tending to pull them apart.

Polyester has OK cohesion; this is reflected in it's basic strength parameters. But is has poor adhesion, so that is does not exhibit nearly the same bond strength (adhesion) that we observe in it's strength and hardness which are the result if its cohesion.

The fact that Polyester has fairly good cohesion is not a good predictor of its adhesion. This is actually true of all materials; one does not predict the other. There are plenty of materials with opposing adhesive and cohesive properties.

Epoxy has both good cohesion and adhesion so it is an obvious choice when doing anything but laying up an entire boat. Remember that when any thermoset polymer cures, technically all the individual molecules of the monomer join into one giant molecule by cross-linking; theoretically ALL the resin on your boat is ONE giant molecule, so anything that bonds to this afterward needs good adhesion. The only time cohesion had a chance at bat was when the boat was layed up in the mold; after that it's all up to adhesion, which poly is piss poor at.


Jimbo

[scotch&water]

Jimbo1490. You have some great points, butin the boat production area you are tabing in stringers bulkheads ect. all in Polyester.The work is done after the hull is constructed, many times with a weekend span or longer frm hull lay up to tabing. We just completed some work on a Buehler Turbocraft and I looked at the stringer the lay uo over the stringer is fine, this boat was build in about 1964. Fritz.

[PAR]

This isn't to say you can't have good work with polyester Scotch&water, but that polyester has limitations, particularly in repair, by a novice. Though to be frank, if you lined up a dozen 1964 polyester hulled whatever's, you'd likely have 11 in need of stringers, transoms, etc.

[quote=scotch&water;292970]Jimbo1490.

You have some great points, butin the boat production area you are tabing in stringers bulkheads ect. all in Polyester.The work is done after the hull is constructed, many times with a weekend span or longer frm hull lay up to tabing.

Yeah, we know why you find enquiries about stringer replacement here every single day!!!

We just completed some work on a Buehler Turbocraft and I looked at the stringer the lay uo over the stringer is fine, this boat was build in about 1964. Fritz.

My oldest ship is from 1910, does that mean all steel boats live 100 years?


Polyester IS NOT and BY NO MEANS a material to be used in boatrepairs!

Was that loud enough???

You may contradict the professionals another thousand times, your stories do´nt change the facts.