Nauticus
If l let my mind wander, its often gone for weeks!
- Messages
- 86
- Location
- Lincolnshire, UK.
any of the epoxys will do , wests is great , but use between fifteen and thirty % xylene to the mix it slows down the hardening to let the epoxy soak in , Ideally you want the hardening time in days , and keep feeding the wood as it soaks it all up , in effect your making fiberglass but using the wood as the glass fibres , xylene is used in the states a lot with epoxy as its is so warm you need a retarder to get the good out of it all. have a wee play and see how you get on. i did prop tunnels on my boat and it took about two months to set ,, but when it did , no more naily tunnels .
Epoxies should not be thinned more than 3%. That is why your prop tunnels took so long to harden. The resin cures but the solvent is trapped in the mix and has to permeate out. That then leads to a porous mix. Part of the curing process is exothermic - the warmer the mixture the quicker it kicks off and cures. When skinning ply boat shells, the thin film of resin and glass lose any exothermic heat very rapidly. The mixing pot, on the other hand will kick off and become hot if not used quite quickly. I find that the shell skinning takes at least six to eight hours to a 90% cure. This is ideal - the glass is perfectly wetted out and the surplus resin has been squeegeed off before the curing process commences. After about 8 hours the epoxy is fully hardened, but not quite full strength. That takes several days. A half full mixing pot will kick off in under 30 minutes.
If you need a longer "wet" time, choose the appropriate resin - such as the blend used for vacuum bagging
There is a wide range of epoxy resins available - from a number of manufactures. I've used most of them. For me, I find that Wests is somewhat pricey and also quite thick. Great if you are building a stitch and glue shell or laminating frames, but I find it hard work to wet out woven rovings. International do a good wetting out resin, but it needs more body for fillets. BluGee is another good manufacturer.
I now tend to stick (no pun intended) with UK Epoxy Resins - https://www.epoxy-resins.co.uk. Rob Hewitt who runs it is a fountain of epoxy knowledge and I find that it is a good 'all round' resin at a good price, and works well for the various projects etc I get involved in.
If this has been mentioned here before, please accept my apologies for duplicating - Epoxy can NOT be be treated like polyester. I do hear people say "Add more hardener to make it cure quicker". This is completely WRONG! A cured epoxy is formed by the perfect amalgamation of two resins. Different manufacturers have different mix ratios (1:1, 2:1, 5:1 etc) The ratios are critical in producing a strong finished product. It is a question of "hands"! The two resins, A and B, each have a fixed number of "hands" per . . whatever . cc or mil. The best and strongest mix will not have NO surplus hands on either resin - every A hand will be holding a B hand. Hope this makes sense for anyone using epoxy for the first time.
One more point. Do NOT ever allow ANY skin contact with any uncured epoxy or its constituent resins. (I use the blue vinyl gloves). You may become 'sensitized' to epoxy. This means severe rashes, blisters, breathing problems, etc etc. Once sensitized to epoxy you are very unlikely to recover from it - which means no more working with or even rear uncured epoxy, ever!
Sorry for the long comment - just hope it helps someone :-)
Malc.