Epoxy

cagey

cagey

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How do I cover a piece of ply 1.0m x 0.30m in epoxy.
Assuming I'm thinking of correct material.
What materials do I need,
Where to buy (Cornwall)
What to do and not to do,
Any easy How to sites
Am trying to achieve weatherproof attractive and possibly strengthened result.
Wood will not be underwater, although open to the elements.
As this a cheap trial before I do the job properly anticipated life 18 months
Keith
 
Mix up the epoxy according to the instructions (After reading a suggestion on this forum I now use a set of digital scales - very easy). Apply with a cheap clean disposable paint brush. Use a hot air gun to thin it, but be careful not to overheat - the idea is to help it soak in. You need three coats. You can either apply the subsequent coats to the almost-cured previous coat, or wait 24 hrs between coats and rub down thoroughly with wet n dry (until the water stops forming beads).
You then need to apply a UV-resistant varnish to protect the epoxy.
I'm sure the epoxy will improve the strength of the ply very slightly, but if you want any useful increase you'd need to use glass cloth. Whatever you do, it would be wise to coat the exposed edges of the ply, probably with 4 or 5 coats to make sure.
I always use SP Systems, other people swear by West Systems - both are good. West have a good informative website and are probably more geared towards the amateur. Having said that I have had excellent tech advice from SP, which is what the above is based on.
www.westsystem.com
www.spsystems.com -but now a part of Gurit, so you may be redirected.
 
Easy if you follow the West instructions. NB if you can lay it flat you can "flowcoat" it - i.e., dollop on loads of it in one coat. Then and it smooth and give a careful finishing coat.

My question would be "why?". I had a mad phase of epoxying everything in sight and UV protecting with varnish.
It all UV degraded and looked a mess in the end, and when it did fall off it did so in sheets. I've been reconverted to old fashioned varnish and my boat looks better for it. Epifanes is my choice - but you'll get other opinions.

NB I love epoxy as an adhesive and for gap filling (mixed with the appropriate stuff), but it's not a coating for me.
 
Re: 500th I have blessing from suzy

Forgot to mention I am laminating 5 pieces of 5.5mm ply into fairly complex curve receiving strong but steady linear loads.
I was originally going to use poly or casco type glues to bond layers but would seem that epoxy is capable of bonding layers, am I right
Keith
 
G'day Srp,

You said >>>Use a hot air gun to thin it, but be careful not to overheat - the idea is to help it soak in. You need three coats. You can either apply the subsequent coats to the almost-cured previous coat, or wait 24 hrs between coats and rub down thoroughly with wet n dry (until the water stops forming beads).<<<

You can thin Epoxy resin with Methylated Spirits up to 40% by weight, this helps penetration without the risk of overheating the resin.

Also, I would advise that using wet and dry over newly cured epoxy should be avoided. The residue left by the curing process should be removed before sanding, as the action of sanding will only spread the contamination.

Starting at the top with a running hose, rub the surface with a plastic scotch bright kitchen scourer till the water no longer forms beads, then sand with a 250 grit, just enough to remove the high gloss only if re coating.

Hope this helps.

Avagoodweekend......
 
West is best use micro balloons / fibres most important i think is to scratch both surfaces to get a good key and clean well with acetone to wipe off any dirt /grease best off luck
 
A chat with one or more of the resin suppliers may well be a good thing. Something to bear in mind that although epoxy coating may not greatly enhance the overall strength it will stiffen the ply conssiderably. One dinghy builder I knew used to reckon coating both sides of ply stiffend the board as much as a board twice the thickness, so you should bear this in mind when planning your lamination. I was always taught that the use of microfibres in jointing was parly to fill vois and partly to prevent the wood sucking the resin out of the joint.
 
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