epoxy v resorcinol

[wardd]

I just read online part of Details of Classic Boat Construction: The Hull By Larry Pardey at

http://books.google.com/books?id=zSH...0rules&f=false

and from page 485 on he discusses epoxy v resorcinol and seems to prefer resorcinol

comments?

[peter radclyffe]

resorsinol has more shock resistance, & needs better joinery ,
its not transparent, thats against it, & does not work so well as a filler

[PAR]

Larry Pardey's dislike for epoxy is well known, so take his advise with a grain of salt, or in his case the whole salt shaker. In fact he considers epoxy water resistant, which is technically correct, but for all intent and purposes, it is truly the waterproof solution. If you want to get technical, general marine epoxy can't pass the mil spec for type one water proof adhesives too, but it hasn't stopped everyone (including the military) from using it as a water proofing.

He's an arrogant, biased old man, that hasn't the rational to accept change. His contributions to traditional construction are notable, but his opinion on epoxy (and other things) again should be questioned loudly, as they fly in the face of both short and long term testing, plus n the field trials over three decades of common use and acceptance. I know I'll hear some crap for this, but I recommend you talk with the man first. After a short time, you see what I mean.

[boat fan]

His contributions to traditional construction are notable

I have read his books.I think he knows his stuff , as far as traditional construction is concerned .I dare say I learned some things from those books too....

But ...that whole epoxy thing ...PAR is right ..his mind is CLOSED there.
To the point of irrational.

It`s pretty hard for the amateur , building in his backyard , to satisfy all the caveats of using resorcinol.
(I can produce a tight fitting joint , but it can take longer) , and its not always easy to get that high clamping pressure either.
I don`t mind the dark glue line , though some would object.

Thank god for epoxy

[peter radclyffe]

PAR thanks for telling us straight ,

[capt vimes]

to my knowledge epoxy is not exactly what you might call a glue... resorcinol on the other hand could be called one...
the wood-wood adhesive strength of epoxy is less then that of resorcinol...

it all depends on what you want to do with the stuff...
laminate some thick transversal stiffeners together from some thinner boards to get the proper shape - resorcinol
fill gaps in some connections, fair something and make the whole thing waterproof - epoxy

i would use resorcinol everywhere where considerable loads are to be expected (ie keelson, backbone, floors, stiffeners in general)...
on the skin i would use purely epoxy just because this really needs to be waterproof...

[TeddyDiver]

My father used resorcinol, and they are both history.. I'm still alive and use epoxy And seriously, epoxy is just more versatile and as glue it's stronger than the wood it's used with.. no worries.

[PAR]

Both resorcinol and epoxy far exceed the fiber strength of the woods they're applied to, so bond strength is a moot discussion.

I still use resorcinol for some things, particularity weight sensitive items, but have never found it gap filling and I'm reasonably confident this will be the opinion of the rest of the users of this adhesive.

Epoxy has easily proven it's value and rightly over taken every other adhesive, bar none in the marine environment and for the most part justly so, though as a coating it's often over used or improperly used.

Some old farts like me, still use plastic resin, resorcinol and other glues we're familiar with, but we'll die off some day and epoxy will be what's left.

[boat fan]

So , how long does it take for resorcinol glue to "set " properly?

I glued some test pieces of wood with resorcinol that had good contact,( not clamped REALLY tight ), but the glue line failed.
No contamination on the wood before gluing , lightly sanded to key the pieces together etc .

There were no voids or air trapped in the glue line itself , but the glue line came apart.

Others were really strong and the wood fibers tore at failure.
Must be because the glue was not "set"? ( 2 days )
It looked ( the glue line ) to be hard and set though ?
These were simple halving joints , but they did fit well.

Never had that with epoxy?.

[Steve W]

Resorcinal is a great adhesive,we used a lot of it back in my apprentice days and i never saw a faliure,ever,however it has many limitations and requires a much higher level of workmanship than epoxy which is why epoxy is so popular.When we used it we tended to use what was appropriate to the task at hand rather than the one size fits all mentality so common these days.On a typical cold molded boat we would laminate frames and floors with resorcinal,glue the stringers with epoxy,glue the first skin to the framework with epoxy,laminate the rest of the skins with resorcinal,dynel or glass sheath with epoxy,glue the deck frame with epoxy,you get the picture.These days we use epoxy for everything because it does everything adequately which no other adhesive does.Epoxy also works better in the inhospitable northern Minnesota climate,christ,it doesnt even get warm enough in the summer for resorcinal.
Steve.

[boat fan]

It doesnt even get warm enough in the summer for resorcinal.

I think you just answered my question.....

[PAR]

You need to clamp the crap out of a resorcinol joint Boat fan, which was likely your problem. Environmental conditions have to be addressed too.

[boat fan]

O K thanks PAR.

2 possible reasons.

I get the feeling Mr Pardey overplayed his hand .......

[Steve W]

BF,the three things that resorcinal requires are close fitting joints,high clamping pressure as Par said and 70 degrees F or higher if i remember right which is better suited for where you are than where i am. Larry is right in some ways though,his boats are mostly Teak and i think white oak backbone,both woods that glue more reliably with resorcinal.
Steve

[boat fan]

I had one out of three..........I think.

70 degrees F or higher if i remember right which is better suited for where you are than where i am.

I think I had just above 50 F.....July ( our " winter ")...I never realized that was too cold...!

Mr Pardey.....I believe in this book "Details of Classic Boat Construction: The Hull" it may have been "The Capable Cruiser " cannot recall for sure now , but he really knocked epoxy. I ( almost ) believed .........

BTW......Steve W....when cold molding , how did you ensure / achieve the high clamping pressure , Is vac. sufficient or did you need staples / screws/ other ...?

PAR is right ...again .......


Epoxy for me .No gamble.