west 7 epoxy vs cheap all purpes fiberglass resin

[KevinK]

ok so I have read a fair bit about plywood tanks, and some use paint + west 7 ore other use only west 7.

now I dont know, but wonder.

industreal plastics sells general purples waxed resin (also used for decking and so),

now :
A- I wonder would this be ok to use for making a sump, display tank ?, is not why not
B – if west 7 needs to be applied, cant you not first build up layers with resin and maybe a mesh ore 2 in there out of the general resin, and kind of paint it off with the west 7.

overall the consideration is that west 7, when needed for a300+ gallon tank (with a thickness of 1/5 inch ore so, will also run in the $$$$, while a 5 gal drum of the general resin is lie only $140 ore so.

not to cut corners, but wonder what the difference would be on the end resold, other than the price tag.

so whome build a plywood tank out of general resin, ore what resin did you use ?

[SmallFry]

I'm assuming by west 7 you mean west epoxy. If that is the cast here are a few things which may be of interest..


West epoxy is good stuff but expensive, and the standard hardeners can create a thing called amine blush which has to be sanded off or scrubbed with an ammonia cleaner - they do a 207 hardener that is more expensive but non blushing. If you get it mail order, expect nasty shipping charges most carriers call it hazmat and bill accordingly. Some people may paint the tank because epoxy in general doesn't like UV at all. There are hardeners that are better for this e.g. the West 207. If you want to get in depth with all of this try looking on the cedar strip canoe building websites (guess why my new tank has been delayed ). Epoxies also stick to wood much better than polyester resins hence their use in wooden boat building - nobody with any sense uses polyester based resins on cedar strip canoes or any other wooden hull for example..

One thing I will say is that epoxies have some irritant properties and some folks are allergic to them.

Polyester resin on the other hand is outright antisocial stuff - lots of styrene which stinks like you wouldn't believe and is really not good for you at all. DO NOT even think of doing it in the house! Don't do it on top of a chest freezer in the garage either, because the food will end up tasting of it even if the hermetically sealed door is never opened (Dad took a LOT of heat off Mom for that one) and I have no idea what any remanants of the styrene might do to your tank inhabitants.

You could paint over the standard polyester resin /glass with epoxy - in fact a good move since polyester resin isn't exactly impermeable to water. Epoxy is..

On balance, if I was building one I'd go for epoxy, the good news though is that there are cheaper suppliers than West, that may be worth researching. On my canoe I used Raka epoxy with the non blush hardener and saved big money over West...

I've not built plywood tanks before, but as far as I've read the strength is in the wood, not the epoxy, it only waterproofs it. If this is the case the 1/5 of an inch you mention sounds a bit like overkill though I'm willing to be corrected here..

Don't know if this helps or confuses you more, but I tried...

Rob.

[randallino]

Smallfry this is a good place to start looking for epoxy's coatings etc, they do carry West systems.
http://www.fibertek.ca/index.htm

[mike31154]

Like Small Fry I know little about plywood tanks but have also built a cedar strip canoe using fiberglass & West System Epoxy. Yep, the West stuff is expensive, but apparently hard to beat. I haven't tried any other brand (just built the one boat so far), but everything I read prior to and during the build steered me towards the West brand.

As far as strength & layering, I can say from experience that my boat is extremely strong & light as well. With cedar strip/fiberglass/epoxy builds, it's actually the fiberglass that adds strength, so I'd guess that if you want to beef up the strength, get some fibreglass cloth & put the epoxy over that in a few layers, same as boat building technique. It comes in different strengths/thickness & is not that costly when compared to the epoxy. After completing the shell of cedar strips, the hull was quite flimsy & flexible. Once the glass & epoxy went on, it became a very rigid, monocoque type structure. Thwart, seats all contribute to additional strength. A few coats of marine varnish finish the job & protect the epoxy from the sun's UV rays.

Sorry, getting a little carried away with the boat stuff here, but hopefully the info will help you out with your research.

[randallino]

Nice canoe Mike!

[mike31154]

Thank you, it took all summer of '05 to build. Wood came from a small outfit in North Van. IIRC he had the epoxy as well. I had Bob's Special out on Kalamalka Lake yesterday afternoon for a paddle. I'd probably do ok building a plywood tank for a sump, but I have a couple glass tanks kicking around for that purpose already.