Plwood

[Steve]

George. . . all I have to go by is my own experience. . .

I was talking to Keith and Seedtick with Bob at the Rendezvous and I had asked them about air bubbles when they applied their saturation coat and I learned from them and Bob that if I applied the saturation coat to wood that had been warmed up I wouldn't have as much problem with air bubbles. . .(Maybe one of those guys could explain the mechanics of that better. . . I just know it works). . . When I got home, I went ahead and set up a piece of ply (some 1/4 inch stuff I had laying around) and let it warm up over night. . . the next morning I applied a sat coat made up 1 to 2 and acetone to thin it. Applying it, I not only avoided the air bubbles I would usually get but I noticed it penetrated a deeper. . .

I also know that I have used an epoxy mixture in preparing spalted woods for turning. . . I suspect that that would be close to the soft woods that Chuck spoke of.

As far as penetrating the glue with the epoxy. . . most glues used by the plywood makers are either set/hardened by heat or a radio wave of some odd sort. . . I understand that plywood makers have various standards, as Jack pointed out. . . still it is much like the debate of whether to use Elmer's white school glue, tightbond I, II, or III, epoxy, or gorilla glue for that matter when building a strip canoe or kayak. . . there, the glue merely holds the strips until the epoxy and fiberglass are applied. . .

When I applied the sat coat to that piece of really warm 1/4 ply, it soaked into the ply deep. . . that's all I can tell you. . .

My use of the word override was an error on my part. . . I believe, like Chuck (I think), that the epoxy FORTIFIES and adds to
the strength when a properly applied saturation coat is applied. It's just up to the boat builder if he wants to stand out in the shop one cold blistery winter's morn in his skivvies after leaving the heat on up high all night to warm up the boat for applying a PROPER saturation coat.........

Now. . . all this is just my opinion. . . there are those who are more expert than I am . . .

Steve

 

[Kayak Jack]

One of us has got to do an experiment with the saturation coats on plywood. I remain skeptical about whether anything is going to saturate past the glue line under the face ply. I just suspect that the glue line is going to stop anything from soaking past it. ...

I suspect you're right.

 

[oldsparkey]

The heat expands the air in the wood and the cold air contracts it.

SO.. If you put epoxy on the cold wood and then it warms up during the day ... Guess what ??? .. You will have air bubbles. Where is you do the opposite :roll: .... and put the epoxy on the wood when it is warm and the weather (Surrounding temperature) is cooling down you will have penetration and no bubbles.

Prime example is this ... The wood is in the shop all day , the temp gets up near 100 then evening comes along and the temp starts dropping , now is the time to saturate the wood. As the temp goes down the epoxy goes into the wood.
Guess you could call it third grade science. :lol: :lol: :lol:

Chuck.

 

[BEARS BUDDY]

See the WEST system site for information on penetration and its effects on plywood. They have done extensive testing on epoxy/wood combinations including different species and types of plywood.

 

[Kayak Jack]

Thanks, Ger. And that URL IS: ____________ ? (waiting here, finger tapping, squinting inta the sun, looking excitedly towards Gerry, (sigh) scratching my ,,,, uhh ,,,, nose)

 

[oldsparkey]

It's not West but a different one ..... http://www.epoxy5050.com/epoxyresin.php3

There opening statement..... " Epoxy resins are powerful adhesives, which when properly formulated, soak into the wood, form a waterproof barrier and add significant strength as well."

Chuck.

 

[Kayak Jack]

And here is an answer to one of Ronnie's questions from a while ago: "NOTE: Epoxy Resin can be used over Polyester Resin. In fact, epoxy adheres better to cured polyester than polyester resin does and is a superior material for repairing fiberglass boats."

 

[oldsparkey]

I'm trying to locate the one web site I found a while ago that made the statement that epoxy will not saturate the glue in the plywood but will saturate the wood down to the glue or about 1/16 of an inch in unless it is thinned then it will saturate in further. Plus the thinning of the epoxy , weakens the total strength of the epoxy by the degree/amount of the thinner used. But since it is adding/increasing strength to the wood while protecting it from water damage if punctured , cut or scraped. Any addition is better then none.

The way I see it , the wood I use is 1/8th inch so by doing both sides the wood is saturated all the way to the glue so the boat is not a plywood boat it is a epoxy-composite glued-epoxy-wood boat , then glassed. :wink:

Now if I can locate that web site , it was some professor ( academic) or something's site on epoxy saturation that I stumbled up on.

Chuck.

 

[BEARS BUDDY]

Thanks, Ger. And that URL IS: ____________ ? (waiting here, finger tapping, squinting inta the sun, looking excitedly towards Gerry, (sigh) scratching my ,,,, uhh ,,,, nose)

http://www.westsystem.com

 

[gbinga]

The heat expands the air in the wood and the cold air contracts it.

SO.. If you put epoxy on the cold wood and then it warms up during the day ... Guess what ??? .. You will have air bubbles. Where is you do the opposite :roll: .... and put the epoxy on the wood when it is warm and the weather (Surrounding temperature) is cooling down you will have penetration and no bubbles.

Prime example is this ... The wood is in the shop all day , the temp gets up near 100 then evening comes along and the temp starts dropping , now is the time to saturate the wood. As the temp goes down the epoxy goes into the wood.
Guess you could call it third grade science. :lol: :lol: :lol:

Chuck.

That's the explanation I would have expected. You want the wood to be cooling while the epoxy soaks in and sets. Makes sense to me.

Not that I have all that much sense...

George

 

[Oyster]

Actually "plywood boat building goes back a bit further. :wink: Blasphemy indeed!

I saw this one yesterday dating back to 1872. This one is a double layered right angle plywood of sorts. So yes Sparky it was a ways back, even though your mind maybe failing too, it was probably along the time of your own example. :lol: Look closely and you will see the longitual planks on the outside while the inside was thwart planked to the hull lines.. This boat also needed no fiberglass or goop to make it water ready either.

 

[Oyster]

Here is another one that the guy had dating back to 1878. This is probably a bit off topic in this thread, but really neat. I would think that the centerboard would be hard to operate and adjust in shallow water though.

 

[Steve]

NOW THAT BE SOME BEAUTIFUL BOAT MAKING THERE. . .

Ya gotta admire the skill it took to build boats that have lasted all those years. . .

You didn't happen to get some shots of the two canoes next to that sailboat, did ya. . .

 

[bluegrasslover]

I stumbled upon this article and it makes me wonder if a saturation coat helps at all in a lot of cases. Look at the section titled "Is thinning necessary?".

http://www.seqair.com/skunkworks/Glues/ ... nning.html

 

[oldsparkey]

There last statement makes me wounder about what they had to say........ We will continue to research this subject and publish our findings in Epoxyworks.

All I know is that it works for me. Saturation , then a light sanding , glass and epoxy. That gives the epoxy with the glass some epoxy to bond to that has soaked into the wood. Not just the wood under the glass as in putting the glass on the boat and then epoxy without the undercoat of epoxy on the wood.

Chuck.

 

[funbun]

All I know is that it works for me. Saturation , then a light sanding, glass and epoxy.

Yeah, That's what I wished I had done with my pirogue. It makes so much sense to do it that way. That's one reason I want to build a new boat: I believe I can build a better boat than my first attempt.