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Old 22-10-2013, 20:36   #31
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Curing epoxy is an exothermic reaction: it gets hot while it cures. When you coat wood with epoxy, the heat that develops will expand air inside the wood and you get zero penetration and millions of little bubbles. The opposite if what you want. Always heat the item you coat. Like minaret wrote, or even using a simple heat gun and patience. This expells air from the wood and creates a vacuum right after coating, drawing the epoxy into the wood.
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Old 22-10-2013, 22:44   #32
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Re: Coating Wood With Epoxy to Prevent Rot

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Since he is talking about a hydraulic bag instead of a vacuum bag the leaks you're thinking of aren't really a concern. Since the bag isn't being evacuated there isn't anyplace for the leaks to go.



I'll be happy to let you be the guinea pig on that one. Let us know how it goes, with pics please!
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Old 22-10-2013, 23:46   #33
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I pull 29.92 inches of mercury all the time. Perhaps some of the wizards around here could tell us the depth you would have to submerge an object to (and the necessary salinity of the water I bet ) to get this pressure?
About 10 meters more or less.
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Old 22-10-2013, 23:50   #34
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Re: Coating Wood With Epoxy to Prevent Rot

I bought some epoxy but couldn't put it on for fear of the wood not being able to breath.
Used Cetol instead. Allows moisture to get out and contains a fungicide.
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Old 23-10-2013, 02:54   #35
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Re: Coating Wood With Epoxy to Prevent Rot

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I pull 29.92 inches of mercury all the time. Perhaps some of the wizards around here could tell us the depth you would have to submerge an object to (and the necessary salinity of the water I bet ) to get this pressure?
Roughly speaking 30 feet of water is one atmosphere, 14.7 psi, 1000 mbar, 29.53 in of mercury. So in the first 30 feet the absolute pressure doubles, 29.4 psi. 60 more feet and the absolute pressure doubles again to 58.8 psi.
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Old 23-10-2013, 04:09   #36
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Re: Coating Wood With Epoxy to Prevent Rot

One atmosphere (101 kPa or 14.7 psi) is the pressure caused by the weight of a column of fresh water of approximately 10.3 m (34 ft). Thus, a diver 10.3 m underwater experiences a pressure of about 2 atmospheres (1 atm of air plus 1 atm of water). This is the maximum height to which a column of water can be drawn up by suction at atmospheric pressure.
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Old 23-10-2013, 04:21   #37
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Re: Coating Wood With Epoxy to Prevent Rot

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I'll be happy to let you be the guinea pig on that one. Let us know how it goes, with pics please!
I actually think trying to impregnate wood with an epoxy sealer like Git Rot by bagging it and throwing it in the water is a terrible idea, however possible it may be.

I was really reacting to the fact that putting something in a bag and throwing it in the water to achieve very high clamping forces is a brilliant idea. Vacuum bagging is great but will only get you so far. Autoclaves are expensive and I don't have one. On the other hand, the water is right there floating my boat. I don't think it would mind if I used it to be a clamp too!
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Old 23-10-2013, 05:46   #38
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Re: Coating Wood With Epoxy to Prevent Rot

Thanks for all your contributions
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Old 23-10-2013, 07:32   #39
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Re: Coating Wood With Epoxy to Prevent Rot

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Originally Posted by Delancey View Post
I actually think trying to impregnate wood with an epoxy sealer like Git Rot by bagging it and throwing it in the water is a terrible idea, however possible it may be.

I was really reacting to the fact that putting something in a bag and throwing it in the water to achieve very high clamping forces is a brilliant idea. Vacuum bagging is great but will only get you so far. Autoclaves are expensive and I don't have one. On the other hand, the water is right there floating my boat. I don't think it would mind if I used it to be a clamp too!


"Terrible idea" and "brilliant idea" all in one short post. Which is it?


And why are we talking about this theoretical method which no one in their right mind would try when I posted a method which is easy and works great with no special equipment?
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Old 23-10-2013, 08:26   #40
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Re: Coating Wood With Epoxy to Prevent Rot

I am in the process of repairing/replacing some of the wood parts of my Samson C-Mist 32, which is a Ferrocement double-ender design very, very similar to a Westsail 32. My new bowsprit is made of 3 Douglas fir 2x6 laminated with West epoxy, finished with varnish for UV protection.
Im exploring the idea of pretreating with an anti fungal agent such as ethylene glycol. Has anyone here tried this?
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Old 23-10-2013, 08:31   #41
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Re: Coating Wood With Epoxy to Prevent Rot

Many years ago, when I was building my boat, a retired firefighter was building a traditional boat in a neighboring yard. He wrapped a firehose, in a spiral, around his built-up mast and turned on the water. The hose filled and swelled, uniformly applying hydraulic pressure to the entire mast and squishing excess glue out of the joints. Pretty clever fella. He also rigged a band saw table to a car's convertible top motor. He could walk toward the saw, cutting a curve, while tapping a switch on a long cord to change the angle of the table, crafting a compound curve for his hull planks. Very, very clever.
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Old 23-10-2013, 08:32   #42
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Re: Coating Wood With Epoxy to Prevent Rot

I also just finished making a new bowsprite as my old one was pretty rotted when I brought the boat. Laminated 10 -3/4" planks with thickened epoxy, shaped it and then coated it with 4 coats of epoxy and 6 on the ends.

Also marked the holes where the anchor roller and pulpit are attached, drilled them out and poured in thickened epoxy for the screw attachments. One more coat of epoxy and then let it dry for about a month. I'm lucky in that I'm part of a wood workers guild and have the use of some pretty amazing tools and facilities including a spray booth. Sprayed 2 coats of primer and then 3 coats of Perfection - turned out really really nice.. I think!
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Old 23-10-2013, 08:35   #43
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Re: Coating Wood With Epoxy to Prevent Rot

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Many years ago, when I was building my boat, a retired firefighter was building a traditional boat in a neighboring yard. He wrapped a firehose, in a spiral, around his built-up mast and turned on the water. The hose filled and swelled, uniformly applying hydraulic pressure to the entire mast and squishing excess glue out of the joints. Pretty clever fella. He also rigged a band saw table to a car's convertible top motor. He could walk toward the saw, cutting a curve, while tapping a switch on a long cord to change the angle of the table, crafting a compound curve for his hull planks. Very, very clever.

How did he see the angle of the table off the gauge while cutting his running bevel? Giant gauge?
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Old 23-10-2013, 08:36   #44
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Re: Coating Wood With Epoxy to Prevent Rot

Steve Bean, Epoxy is vulnerable to ultraviolet light and will peel and fail within months. Ever notice how varnish does the same thing? Do yourself a very big favor. Cover the epoxy with an opaque paint, like white, to reflect UV and protect all the work you've done.

And forget about the glycol. It will only screw up the bond of the epoxy to wood. Just coat the wood correctly and keep it painted. It will last a very long time.
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Old 23-10-2013, 08:40   #45
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Re: Coating Wood With Epoxy to Prevent Rot

Minaret, he did a couple of trial cuts and determined the frequency and duration of the pressing of the switch. He had a pretty good idea of the bevels he would produce. Of course, afterward, he cleaned things up with a plane.
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