glassing plywood prior to hull installation

[smj]

https://sourisriverdealer.wordpress....ylester-resin/

[Terra Nova]

smj--from that article:

Epoxy resin is known in the marine industry for its incredible toughness and bonding strength. Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters.

[smj]

Originally Posted by Terra Nova

smj--from that article:

Epoxy resin is known in the marine industry for its incredible toughness and bonding strength. Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters.

Yes, what's not to love[emoji106]🏻. As my boat is all epoxy construction I don't have the option of using polyester, though if it were polyester construction, I can't think of many instances where I would use polyester on it anyway.

[ramblinrod]

Originally Posted by smj

https://sourisriverdealer.wordpress....ylester-resin/

Seriously?

Who would one use polyester resin to repair a Kevlar/epoxy canoe?

Now for a polyester resin FRP canoe, boat, Corvette Stingray, water tank, chair, bathtub, whatever, I would use polyester resin to build or repair that in a heartbeat.

I would match the original gelcoat and it would be very difficult to detect the repair, would last the life of the article repaired, and the resin would cost 1/4 as much. What's not to like about polyester?

[smj]

Originally Posted by ramblinrod

Seriously?



Who would one use polyester resin to repair a Kevlar/epoxy canoe?



Now for a polyester resin FRP canoe, boat, Corvette Stingray, water tank, chair, bathtub, whatever, I would use polyester resin to build or repair that in a heartbeat.



I would match the original gelcoat and it would be very difficult to detect the repair, would last the life of the article repaired, and the resin would cost 1/4 as much. What's not to like about polyester?

It's properties.

[jimbunyard]

Originally Posted by Terra Nova

smj--from that article:

Epoxy resin is known in the marine industry for its incredible toughness and bonding strength. Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters.

Typical Bernaysian hype, and usage, and non-explanation.

The first paragraph of the 'article'.

"Here’s a different way to look at epoxy resin vs. vinylester resin as was explained to me by an R & D chemist named Mike Daniels. Mike works for a huge Minnesota company and he does know his chemistry. Plus he has 25+ years of making all kinds of cool stuff and is an expert wood crafter. His stripper canoes and kayaks are rather spectacular. You just can’t help but trust a guy who is a seasoned chemist, canoe builder, and canoe paddler."

What a list of credentials! And of course, sources (0) backing the 'claims' up....

The first sentence of their website;

We sell Souris River Canoes.

and just a single click away...

Carbon-Tec 53 lbs. $3,700


Which I'd call a pretty good reason for promoting the 'higher quality' of their canoes over others. As they say,

"Compared to Souris Rivers, I consider other brands of canoes junk.".

Certainly an unbiased source for getting information about the bond strength of epoxy versus, well, anything at all.


And of course we have the unsourced, unsubstantiated claim that

"Quality epoxy resins stick to other materials with 2,000-p.s.i. vs. only 500-p.s.i. for vinylester resins and even less for polyesters."

which has problems from the first word. What is 'quality' epoxy resin? Is that some kind of brand? What about these mysterious 'other materials'?
So epoxy sticks 400% better than vinylester to everything? Wonder how it works on HDPE? Or Teflon? Or AlMgB14?

And please explain how, even though the other mechanical properties of epoxy and polyester are very close, percentage-wise (as listed in my sourced post 148 above) that the bond strength of epoxy is somewhere north of 400 percent more when compared to polyester? (of course our happy canoe dealer couldn't be bothered to do his research and provide us with a real number)

And neither will anyone else, because as written the statement is meaningless and unquantifiable.

But ya'll can believe whatever you want, as Barnum (probably apocryphally) said 'There's one born...'

[Terra Nova]

Originally Posted by jimbunyard

...Certainly an unbiased source for getting information about the bond strength of epoxy versus, well, anything at all....

Certainly as unbiased as some of these other unbiased posts.

And about as accurate as this magical 20% that some keep bringing up.

Bottom line is: Take with a grain of salt any epoxy advice that comes from someone who is too afraid it's going to kill him, and so uses polyester almost exclusively.

[smj]

https://youtu.be/rw3Uf6bPPds

[Three Sisters]

Is there a specific epoxy that is being bandied about here. I've read back a few pages and cannot find where the epoxy type is mentioned.

Is it a 1:1 or maybe a 3 or 5:1 epoxy. A 1:1 is rather flexible if you bend a sample. 3:1 will snap with slight effort.

[UNCIVILIZED]

Originally Posted by Three Sisters

Is there a specific epoxy that is being bandied about here. I've read back a few pages and cannot find where the epoxy type is mentioned.

Is it a 1:1 or maybe a 3 or 5:1 epoxy. A 1:1 is rather flexible if you bend a sample. 3:1 will snap with slight effort.

To what epoxies are you referring when you site these supposed flexural characteristics based on mix ratios? And what does mix ratios have to do with it? As there are all flavors of the amount of hardener to resin, & such figures aren't necessarily brand specific. Along with the fact that you can have a number of resins with the same mixing numbers, but vastly different physical properties... within one brand of resin, or from one manufacturer to another.

Guys, I'd like to think that a good part of my coming to the forums is to learn. But some of the stuff in this thread is beyond silly, & has me reaching for the ignore user switch. Something I almost never, ever do.
So at this point if you're going to site references, brands, properties, etc., please be very specific. Or the claims which are being made amount to even less than heresay. AKA fluff, to put it politely

BTW, there's loads of more detailed info on these kinds of things on various other forums. Perhaps such are better locales to post on such. Not that they're ideal either, but...

[ramblinrod]

Originally Posted by Terra Nova

Certainly as unbiased as some of these other unbiased posts.

And about as accurate as this magical 20% that some keep bringing up.

Bottom line is: Take with a grain of salt any epoxy advice that comes from someone who is too afraid it's going to kill him, and so uses polyester almost exclusively.

Lets not get any more stupid about this.

If you have a choice between using two different products that will be adequate for the job, one costs 4 times as much and may kill you. which one should be used?

It is truly that simple.

[ramblinrod]

Originally Posted by smj

https://youtu.be/rw3Uf6bPPds

Cute,

I've spent a whole lot of years listening to total BS, and this takes the cake.

What does this experiment prove?

That when one attempts to adhere some undefined material to another undefined material, following an undefined procedure, that an undefined epoxy is stronger than an undefined polyester, assuming the sample prep (undefined) was identical.

So what?

My posts have been related to bonding polyester FRP and wood. Polyester is great for this.

How good is epoxy at bonding paper to water?

That's about as relevant.

[Three Sisters]

Those are the properties of the brand of epoxy that I use.

Actually it is confusing if you are asking or telling me.

[mitiempo]

Originally Posted by ramblinrod

If you have a choice between using two different products that will be adequate for the job, one costs 4 times as much and may kill you. which one should be used?

Please show us evidence that epoxy can kill if one is using normal safety procedures.

Also please show us evidence that polyester it totally safe.

[Three Sisters]

Originally Posted by ramblinrod

Cute,

I've spent a whole lot of years listening to total BS, and this takes the cake.

What does this experiment prove?

That when one attempts to adhere some undefined material to another undefined material, following an undefined procedure, that epoxy is stronger. assuming the sample prep (undefined) was identical.

So what?

My posts have been related to bonding polyester FRP and wood. Polyester is great for this.

How good is epoxy at bonding paper to water?
That's about as relevant.

Are you a polyester resin salesman ?