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View Full Version : Which epoxy hardener to use for a mast? 206? 207?



PaulGrun
04-23-2012, 08:53 PM
The time has come to strip and refinish both sticks in Wm. Garden Eel canoe yawl. I've stripped the varnish off and have decided to coat both sticks in epoxy before applying varnish. Here's the question: I am familiar with Westsystem 105 Resin and 205/206 hardener, and all other things being equal I would use 105 + 206 for the masts.

But someone mentioned the other day that 207 hardener would be a better choice with the reason given that it will withstand sunlight somewhat better than 205/206. 207 is also supposed to be closer to 'clear', which is not a big issue for me...I am perfectly fine with the warm amber tones of varnish over epoxy.

Before someone goes off on a rant, I still plan to varnish the masts after the epoxy treatment for UV protection and to ease year-in-year-out maintenance. maintenance and for UV protection.

So what say you? 206 hardener, or 207 hardener?

Bob Cleek
04-23-2012, 09:30 PM
Neither. Use Smith's Clear Penetrating Epoxy Sealer ("CPES") as a sealer beneath varnish. It's pretty much the industry standard for those who don't simply prime with a thinned first coat of varnish. It's designed as a sealer, unlike ordinary epoxy resins. It will extend the life of a varnish coating rather substantially. I think you'll find the generall consensus is "CPES or nothing at all."

PaulGrun
04-23-2012, 09:37 PM
Thanks Bob. I just noticed another thread on this forum on finishing masts, and the consensus opinion there seems to be either CPES or nothing at all. Thanks for your thoughts...much appreciated.

seo
04-23-2012, 09:56 PM
What are you hoping that the epoxy will do? I've never heard that epoxy has much resistance to UV, so obviously the varnish is critical. If it's just a sealer...

PaulGrun
04-23-2012, 10:24 PM
Epoxy doesn't have much/any UV resistance. What I was hoping to accomplish, in this case, was to reduce annual varnish maintenance by stabilizing and sealing the underlying wood, thus prolonging the life of the varnish.

The varnish, of course, also protects the epoxy from UV.

seo
04-24-2012, 09:24 AM
For sealing wood before varnish, I go around between Zspar "S-94 Acrylic sealer" which is nasty smelling, very quick, and penetrates like crazy. I also use CPES, but don't have a long-term view of its effectiveness. It doesn't seem to be used as much in New England as in the Northwest. Why? Dunno. It may be that New Englanders are hidebound traditionalists. Or it may be that the denizens of the Northwest spend too much time in Humboldt County, and have a tenuous grip on reality.
Another method that I've had very good luck with is to start with several coats of thinned out oil. I use Waterlox, but I think tung oil would also work. Then I start adding a small amount of varnish, increasing the proportion of varnish with each coat until the wood is fully saturated, and then finish off with varnish. This takes a long time to do, but I regularly see a sitka mast that I did this way in 1982, and it has never been wooded down and still looks good.
I used to wet-sand the wood with oil as I was building up the oil/varnish, but that leaves a residue of the black abrasive, which isn't ideal. ScotchBrite works better.