Whats the best wood glue?

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john mac

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as the title says really, i'm re-building an old cabin cruiser and need a good glue/resin for the plywood hull, does anyone have any experience of wooden boat building and what glue did you use? cheers.
 
Polyurethane glues are probably the best all round glue for repair work. Single pot, moisture curing, gap filling and does not need high clamping loads. Epoxy is the most versatile as it can be used as an adhesive, filler or as a structural material depending on what additives you use. However, it requires more skill, is temperature sensitive, does not like moisture and needs UV protection.
 
cheers guys, I can buy cascamite and PU glue in my local hardware store just a mile up the road which is handy, both are strong, and should do the job, but other people have told me to use epoxy only. I know epoxy is much stronger, but given my lack of experience with glueing wood, and i'm building the boat in an old barn so very hard to regulate the temperature, there is a lot of opportunity for it to go wrong. So it's looking like cascamite or PU, question is which has the better gap filling capabilities?
 
Isn't cascamite a water based glue?
We use polyurethane D4 glue for fixing down flooring to joists and on the joints of the chipboard which then foams up and seals the joint before the building can be covered in.
Not sure if its any good for boats but I wouldn't use cascamite.
 
russ said:
Isn't cascamite a water based glue?
We use polyurethane D4 glue for fixing down flooring to joists and on the joints of the chipboard which then foams up and seals the joint before the building can be covered in.
Not sure if its any good for boats but I wouldn't use cascamite.
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Wasn't Cascamite used for building the wooden framed Mosquito plane in 2nd World War?
I used it some twenty years ago in making bee hives which got pretty wet and subject to
some abuse in cracking the sections apart to break the propolis.
 
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Cascamite is a powdered Urea-formaldehyde resin. This type of glue is used in all sorts off "stuff" such as MDF (which is why you shouldn't burn it) and is well proven. I've only ever used it for laminating wood together for which it is excellent. PU glue is good for rough joints and quickly putting things together as it foams up to fill gaps and cures quickly. Epoxy is not very nice stuff, slow to cure, and tends to run out of joints if unthickened but used correctly with the right fillers is strong and water resistant. You pays your money and takes your choice but for me the PU glues are very easy to use most of the time.
 
There is only one choice for the application you have in mind, and that is epoxy. Specifically, SP 106 and microfibres as the thickening agent (or the West System equivalent, whichever your local stockist sells). It is the only adhesive system which will tolerate the inevitable gaps and mismatched joints that boat restoration entails.
PU is good for new work, but I wouldn't use it below the waterline or for very exposed situations, and it doesn't fill gaps in the structural sense. Keep it for the internal joinery.
Waterproof PVA is good for internal, non-structural joinery (locker doors etc) - it isn't as waterproof as the manufacturers like us to believe, but it is clean and simple to use.
Cascamite is very brittle when cured, and relies as much on mechanical fastenings to maintain the joint as it does on its' intrinsic adhesive properties. There was a limited choice of really waterproof glues 30 or 40 years ago, but nowadays epoxy is superior in all respects.

Of the above, both epoxy and PU, and the associated solvents, mean that you need to be a bit careful, ie wearing gloves and using a mask when sanding. The West Systems web site is a mine of information, with lots of useful tutorials on repairs with epoxy.
 
srp said:
There is only one choice for the application you have in mind, and that is epoxy. Specifically, SP 106 and microfibres as the thickening agent (or the West System equivalent, whichever your local stockist sells). It is the only adhesive system which will tolerate the inevitable gaps and mismatched joints that boat restoration entails.
PU is good for new work, but I wouldn't use it below the waterline or for very exposed situations, and it doesn't fill gaps in the structural sense. Keep it for the internal joinery.
Waterproof PVA is good for internal, non-structural joinery (locker doors etc) - it isn't as waterproof as the manufacturers like us to believe, but it is clean and simple to use.
Cascamite is very brittle when cured, and relies as much on mechanical fastenings to maintain the joint as it does on its' intrinsic adhesive properties. There was a limited choice of really waterproof glues 30 or 40 years ago, but nowadays epoxy is superior in all respects.

Of the above, both epoxy and PU, and the associated solvents, mean that you need to be a bit careful, ie wearing gloves and using a mask when sanding. The West Systems web site is a mine of information, with lots of useful tutorials on repairs with epoxy.
Click to expand...


Why not use PU underwater ? I thought most underwater structures in the oil industry (bend restrictors, pipe claddings etc) used PU / PU as a binder for microspheres to make syntactic foam ? Certainly the bonding of PU to anything containing active hydrogens (like new and old wood, skin etc) is excellent as the isocyanate actually reacts with hydroxyls .

How can you compare the gap filling of (epoxy+ filler) to PU with no filler? Epoxies with no filler have don't have much gap filling capability; PU with no filler at least will expand to fill the gap if there's moisture there !

Maybe I'm biased as I work in the PU industry !
 
cheers guys, I don't like the idea of cascamite fracturing, this boat will spend most of it's time in the sea and choppy water could cause the joints to split leaving only the screws between me and a long swim home! I'm thinking of using west systems 105 and 206 with 406 filler (when required) for the frames, deck and hull, with PU for pretty much everything else. With a good thick fiberglass skin on the hull and good marine paint inside i'm hoping this will make for a strong boat that won't need any maintenance for a long time?
 
john mac said:
cheers guys, I don't like the idea of cascamite fracturing, this boat will spend most of it's time in the sea and choppy water could cause the joints to split leaving only the screws between me and a long swim home! I'm thinking of using west systems 105 and 206 with 406 filler (when required) for the frames, deck and hull, with PU for pretty much everything else. With a good thick fiberglass skin on the hull and good marine paint inside i'm hoping this will make for a strong boat that won't need any maintenance for a long time?
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Epoxy is easy to use;West systems do some excellent educational booklets-I think you can find them online,though most is about grp.
There are a few provisos-it does need 15 degrees+;be aware the the more "bulk" the quicker it will go off..in simple terms a mug full of it will get very hot quickly, but a paint tray will remain usable for much longer. In the curing process it usualy forms a wax surface-quite obviosuly so in less than perfect conditions. The epoxy will chemically bond to itself as long as it hasnt gelled. If it has, you need to scrub off the waxiness, wash,dry,sand.. only then recoat. In other words, it is a great resin if you can get on with the job, but if it is going to be piecemeal, you have to prepare the surface again each time.
Having said that, I think it is the only "glue" to use, and you just have to accept the cost.
Note the mixing ratios...!
 
GrahamHR said:
Why not use PU underwater ? I thought most underwater structures in the oil industry (bend restrictors, pipe claddings etc) used PU / PU as a binder for microspheres to make syntactic foam ? Certainly the bonding of PU to anything containing active hydrogens (like new and old wood, skin etc) is excellent as the isocyanate actually reacts with hydroxyls .

How can you compare the gap filling of (epoxy+ filler) to PU with no filler? Epoxies with no filler have don't have much gap filling capability; PU with no filler at least will expand to fill the gap if there's moisture there !

Maybe I'm biased as I work in the PU industry !
Click to expand...
:) Maybe I'm biased because I have had PU joints fail when the wood is subjected to extreme moisture conditions. I'm not saying that PU doesn't survive underwater, just that the wood can move too much for it to have much of a chance. Maybe you use different adhesives to the ones available to me as a joiner.
As for gap filling, I'd need you to convince me that PU is capable of providing any sort of structurally sound gap fill (and I'm talking about Balcotan or Titebond PU, both of which I use regularly). I've never used PU with a filler (probably because it is not available to mere mortals like chippies), but I usually use a filler or reinforcing cloth of some sort with epoxy, so I'm comparing two adhesives as they are commonly used - agree it's not necessarily a fair comparison, but that's the choice available in the local chandlery :)
Anyway, as is usual in threads like these I have learnt something from your post - I didn't know that PU had applications like the ones you mention. Have you got any more info on binders for PU, and maybe other marine applications? Cheers.
 
"PU" covers a huge variety of material properties , ranging from filled, very rigid materials (e.g. used for medium voltage electrical switchgear housings) to the supersoft viscoelastic foams. Car bumpers/ body kits to seating, integral skin headrests and steering wheels. Rigid foam for fridges, insulated building panels to cast PU used as automotive suspension parts. With virtually everything in between the extremes possible; it's all down to how it's formulated. As to your question about binders, steam cured flexible PU binders are used to make rebond foam/ rebond foam carpet underlay and rebonded rubber matting/ sports tracks. It's (as MDI) also used to make water resistant chipboard and plywood ( but is more expensive than urea formaldehyde binders). Similar products ( and related polyureas) are used as spray elastomers for concrete/ metalwork protection and truck bed protection. Polyureas have extreme hydrolysis resistance but their reactivity is a bit "fast" to put it mildly !
 
russ said:
Isn't cascamite a water based glue?
We use polyurethane D4 glue for fixing down flooring to joists and on the joints of the chipboard which then foams up and seals the joint before the building can be covered in.
Not sure if its any good for boats but I wouldn't use cascamite.
Click to expand...

Surprised at that from a carpenter Russ... I used Cascamite to build a catamaran out of ply once and it worked very well. Remember that plywood is a laminate anyway and I was always told that cascamite was stronger than the interlaminate bond of even the best marine ply. I did a test before using it and glued a dummy chine piece with it and bent it until it broke. Sure enough it failed inter-laminal within the ply before the cascamite gave way..... Its significantly stronger than foaming PU!
 
boatmike said:
Surprised at that from a carpenter Russ... I used Cascamite to build a catamaran out of ply once and it worked very well. Remember that plywood is a laminate anyway and I was always told that cascamite was stronger than the interlaminate bond of even the best marine ply. I did a test before using it and glued a dummy chine piece with it and bent it until it broke. Sure enough it failed inter-laminal within the ply before the cascamite gave way..... Its significantly stronger than foaming PU!
Click to expand...

foaming PU is carp to use & messy.

Cascamite is from memory a resorcinal glue
Aerolite needs a urea hardener
Aerodux 500 was good for teak
the top 2 leave no glue line unlike PU & that is a lemon coloured line
 
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