How to treat plywood?

chicubs08

Seaman
Joined
May 20, 2008
Messages
73
I just replaced a piece of plywood by the ski locker. I used regular plywood, not marine grade. How do i treat it and make it water proof? Thanks
 

a1nowell

Chief Petty Officer
Joined
May 12, 2009
Messages
437
Re: How to treat plywood?

I redecked my pontoon boat this past year and could not aford marine plywood. I bought 3/4" BCX plywood, the X means exterior glue. I coated it with Waterguard, manufactured by Olympic, I bought it from Lowe's.
 

valor_7

Cadet
Joined
May 11, 2003
Messages
28
Re: How to treat plywood?

epoxy resin is supposed to be the best as far a durability and strength but cost is high, around $80 for a gallon. Polyester resin is half the cost. I'll be putting in my floor next weekend and I plan on coating the top, sides and botton with thinned polyester resin. Thinned so it can seap into cracks.
 

danond

Lieutenant Junior Grade
Joined
Jun 11, 2007
Messages
1,118
Re: How to treat plywood?

It doesn't need to be thinned; if anything, thickening it will provide better protection and sealing.
 

Mark42

Fleet Admiral
Joined
Oct 8, 2003
Messages
9,334
Re: How to treat plywood?

...... I'll be putting in my floor next weekend and I plan on coating the top, sides and botton with thinned polyester resin. Thinned so it can seap into cracks.

Its a good idea to protect the wood, but remember that thinning resin generally results in a weaker resin after cure. Thinned resin will seep into cracks better than straight resin, but as far as soaking into the wood, thinned and straight soak in about the same, although there may be more creep of the thinner agent, which will buy you nothing.

If you use a thinned coat, don't thin more than 20%, and follow with a straight coat. Also the best plan is to include some CSM or cloth in the coating, because straight resin (especially polyester) tends to crack easier when there is no glass to give it strength. Glass in resin is like rebar in concrete.

When glassing the recessed deck pieces installed in my Capri, I didn't bother to glass the edges, it was just too much trouble to try to glass 5/8" wide edge. But it doesn't appear that the edge will be a problem especially seeing how much resin gets sucked in the end grain plies.
 

Mark42

Fleet Admiral
Joined
Oct 8, 2003
Messages
9,334
Re: How to treat plywood?

A good example is the home built wood canoes that have a coating of resin and glass to protect the wood. They typically use a 8oz cloth with resin so the resin is a little tougher and can handle banging and scrapes better. Same works for the deck of the boat.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,525
Re: How to treat plywood?

Most paint or stain type coatings do little to protect the wood, polyester alone is of almost no value because it will soon begin to crack, epoxy lasts longer but will still fail, the time line depends on the wood and epoxy used.

Add glass to either type of resin and the protection can last for many years, you still need to do a good job though.
 

seven up

Petty Officer 1st Class
Joined
Jun 4, 2006
Messages
275
Re: How to treat plywood?

Further down the list after epoxy and polyester in water resistance is shellac. If is still avialable.
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
25,834
Re: How to treat plywood?

or spar varnish with multiple coats sanded between each coat....
 

halas

Petty Officer 1st Class
Joined
Jan 27, 2009
Messages
347
Re: How to treat plywood?

Please !!!no shellac!!!
 

tmcalavy

Rear Admiral
Joined
Aug 29, 2001
Messages
4,005
Re: How to treat plywood?

And open all doors for the plywood, too...otherwise dinner and a movie and fresh flowers will get you nowhere.
 

jpmurphy

Petty Officer 1st Class
Joined
Jan 14, 2009
Messages
358
Re: How to treat plywood?

Did we chase him off ?? Hope not. :eek:
 

Yacht Dr.

Vice Admiral
Joined
Feb 26, 2005
Messages
5,581
Re: How to treat plywood?

Hello cubs..

Yes .. how to waterproof your ply after install ? that is your question right ?

you already skipped ahead.. too far ahead..

wet all dry areas of ply with 20 % thinned resin/acetone .. dont let cure.. repeat when ply stops soaking.. apply full resin ( without wax adds ) when tacky but not fully cured.

YD.
 
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