Hands on Experience of Bonding Heavy Laminations Using Epoxy?


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Aerolite was one of the first UF glues, I have much experience of it courtesy of my Dad who used it extensively in boatbuilding. It is very economical in use & the two part nature is good. (Dont get the acid hardener in a cut as it stings summat awful!) I helped him build several glued clinker sailing dinghies plus many masts & spars it was really good for this. Not least because it is very resistant to UV light & on a varnished spar or boat this is vital!
Cascamite is a related UF glue that has a dry powder hardener mixed into it, this means an air bubblefilled joint compared to aerolite.
Both have a lifespan of approx 30 years after which they start to break down, go brittle & lose their integrity.
I reglued a wooden mast last year using aerolite, about 40 years old the cascamite holding it together had failed & all it took was a machete tapped in one end & tapped along for it to fall in half.
In boatbuilding circles polyurethane glues are not well regarded as their UV resistance is even worse than epoxy.
That actually rings bells Keith.

I built a plywood canoe way back in the very early 1970s with an older guy who provided the adhesive. It was a white powder that was mixed with water. A formic acid (vinegar smelling) hardener was brushed on the other surface.

It was good stuff. One downside was perhaps that it set very hard. I laminated some paddle shafts using it and they poved very brittle - which could well since I was very young and inexperienced (teens) have been down to choice of wood and/or the layout of the laminations....
I Use the aerolite one shote which is a powder mixed with water (same as cascamite). Very easy to mix and good open time. Very rigid glue line sets like glass but some people report it as hard on plane blades etc
I have done many such jobs making laminated deck beams & other components for boats.
Good prep is essential & nice clean surfaces, you can glue straight off the circular saw but sanding is good.
Always sand a tiny radius on the outer face corner of each lamination, if its a heavy bend & there is the smallest nick in the grain its liable to break at that point.
Dont make your laminations too thick for the bend, more thinner ones means less spring back when you take it off the mold.
Its often good to have a dry run, make sure the mold is strong enough & has enough places for clamps, Set as many clamps as you can so they are ready to be wound up. Nothing worse than having to unwind clamps in a hurry!
Use plenty of brown parcel tape on the mold so the epoxy dont stick to it!
When gluing up start with the bottom one & butter up with a flat stick, dont skimp as a starved glue joint is bad. Too much wastes glue! As each lamination is laid on top of the glue bang a fine brass panel pin in the middle & about a third from the end, stops them sliding about.
When the stack is assembled clamp on the mold in the middle & work outwards alternating sides as you go.
Sometimes the stack will start to twist Or some strips lift, squash them back into line with a clamp.
When done scrape off as much glue as you can.

Top tip, Make sure your mold is well supported, Last summer i had a big lamination job on a boat, kind of a half hoop chine piece for the stern of the launch im rebuilding, section was about 35mm deep & 12 3mm laminations about 8ft long. I laid the mold on my sawbench, glued up & started clamping, halfway round the weight of the clamps over balanced it & the whole lot came crashing over. It was very hot & the epoxy was starting to kick even though i had used slow hardener. Much terrible gnashing of teeth & dreadful swearing ensued as i got the mold back onto the sawbench & this time clamped it down. I got away with it but it was nearly a write off.
I was liberally covered in epoxy! Most boatbuilders will have experienced a similar balls up!
All good advice. I Iaminated 2 x 10 ft curved outriggers for a sailing canoe. Involved clamps every 4 inches onto a form screwed to the workshop floor. Epoxy everywhere, lots of expletives and panicked tightening and loosening in an attempt to get the 8 very slippery laminations in place before the epoxy started going off. Happy days.
There's a whole set of skills associated with using epoxy - but once learned it's not bad to work with. It's easy though for a person used to flinging PVA about to get into trouble.

The biggest downside with the stuff in many ways is the inevitable mess. That and how nasty it could be if you accidentally wiped an eye or something with a finger with a trace of hardner on it.

I bought some rolls of light gauge and cheap polythene sold by Screwfix (a UK originating discount seller of hardware and related stuff) for covering furniture and floors when painting - it's cheap enough to cover more or less everything with and epoxy doesn't stick to it.

For sure very careful planning and preparation (and dry runs) are needed before anything gets mixed : )
How about pinning the laminations with a dowel to aid location and stop movement?

I used some cheap epoxy last weekend for a canoe I made and I didn't seem as pungent as I remember it in the past and didn't kick off half as quick?!🤔🤔
what a cracking good discussion.....
very interesting .....
thank u.......

looking to do something similar soon......old truck wooden framed cab repairs........
PS Ash is not available here......
broke up a couple of large Sofa's for the Beech framing.....
Most hardwoods available here come as rough sawn and not been stickered for drying.....very wobbly.....
most of it is very expensive fire wood......
Re laminations sliding about, I always pin laminations together with fine brass panel pins, at the ends & every two ft or so, nail it on then spread the glue, next one on nail it on spread glue & so on. In practice fine pins dont affect the bending or finished result , but they make the stack easier to control!
My son & i did a big lamination job a few weeks ago, a pair of laminated cross beams for an outrigger canoe.
11 laminations 9mm thick x 50mm wide 6m long. We used every big clamp i had & then some!
Re laminations sliding about, I always pin laminations together with fine brass panel pins, at the ends & every two ft or so, nail it on then spread the glue, next one on nail it on spread glue & so on. In practice fine pins dont affect the bending or finished result , but they make the stack easier to control!
My son & i did a big lamination job a few weeks ago, a pair of laminated cross beams for an outrigger canoe.
11 laminations 9mm thick x 50mm wide 6m long. We used every big clamp i had & then some!
Big canoe!

Any pics?!!
Im a bit confused as to the application of this. Are you sure you're not overthinking things.
It's basically just boards glued together, not curved or anything, so a simple pva or cascamite would do the job as well as anything.

I saw a post above about not putting too much on 'Waste of glue', glue costs nothing, as in squeeze out of glue, and yes especially on the edges to prevent starvation.
I would use pva and get yourself a big bloody plane :D
Hi Triton. Most of the guys posting seem to have been doing curved parts or beams from thin laminations - but that's AOK.

My situation is different - I'm laminating planed up 40mm thick flat boards for a very heavy bench in beech which is in some respects a bit more straight forward. It's possible to use Dominos or biscuits for example so that the boards are reliably located.

I nevertheless have been very happy to get the feedback as there's a lot of overlap regarding techniques and general handling of epoxies.

For sure the job could be done with PVA, but I'm wary of the possibility of creep given the heavy parts.

I've gone for West G Flex 650 (it's bought) which is a high flexibility epoxy which West US have advised based on high/low moisture content cycle testing is the best choice - the bench will be lightly finished and in a workshop.

Standard rigid epoxies don't do all that well if the wood moves due to moisture content changes. (the epoxy itself is waterproof, but the wood fails adjacent to the bond line)

The moisture problem is typically controlled in boat applications by sealing the timber with coat(s) of epoxy - but that's not an option for a bench.

It's possibly overkill, but I prefer given the design and make time and the cost of what is high quality clear German beech to be safe rather than sorry. It also given the high cost of the epoxy and the more difficult clean up brings into play the need to get the applied amount right - which was what triggered the thread initially.

I've been running some trials on small workshop projects and the like and find the G Flex 650 handles nicely - its viscosity is about right for use in larger area joints with accurately flat faces kept horizontal. Moderate clamping after using a dialled in fine notched spreader produces a nice thin bondline, not much waste and a very strong joint.

The thickened G Flex 655 would probably (?) be a better choice in circumstances where there could be some gaps in the joint, especially if it is vertical...
Big canoe!

Any pics?!!
That is tasty!!

I've built a flo mo big guide over the bank holidays.

16ft x44" didn't realise how big it would be!

This is a Mill Creek. The big guide is a bit more beamy .This is really a decked canoe about the same length as yours, the main hull beam is 33 inches. Its more like an open boat than a kayak. The 10ft breadth with the outriggers gives it a lot of stability, usually sails with one outrigger flying. Goes on the roof of umy car, assemble on the beach. Great fun.
Its Hawaii five 0 :D
Daa da daa da dda da

That is really cool and a sail too. I would love to sail that.
How does it handle ?. never tried a tri, does the main furl with the mast revolving ?
It is predictable slow through a tack, but great on a beam reach. The sail does furl round the mast. I've got it set up with a Norwegian style tiller, and usually sail kneeling on a foal pad. It's got a reasonable turn of speed. In my book nothing beats sailing something you built yourself.