On sealing wood waterproofing edges

[RogerDat]

My question is an attempt to tap into the wealth of experience in fiberglass, epoxy, and paint on the site. May prove useful for general camp projects even though my use is not directly related to camping.

I need to replace the wood surface of a dog agility A-Frame. My agility equipment gets exposed to the weather and plywood tends to delaminate from moisture after a few (too few) years. I know a fair amount about finishing wood but am stuck on the "best" way to seal the edges.

I have pretty much decided to use medium density overlay (MDO) also known as sign board for the wood surface. MDO does get used for marine applications in place of marine plywood for some uses. Essentially MDO is plywood with paper face for painting and highly waterproof glue.

The top surface has to either have sand in the paint or a granular rubber surface glued onto it for traction. It's kind of expensive and takes a lot of time to re-surface one of these so I'm hoping to come up with a solid solution based on the experience and ideas of others.

For those of you who want to see what I'm working on.

http://www.fiberglassrv.com/forums/m...icture3906.jpg

Main Questions:
Am considering epoxy or fiberglass to seal the edges before painting. Which would you use and why.

Do you have a totally different solution to sealing the edge grain of plywood.

Not sure about the paint. Have had middlin success with porch and floor oil based on some outdoor stuff. What would you suggest?

[Bruce Wray]

Varathane makes a water-based marine grade "spar varnish" Basically it's clear liquid plastic. I've used it on a number of plywood pieces that have held up to river rafting for many years -- totally seals the wood. I did about six coats. Sandable and paintable.

[stevebaz]

If it were mine and I only wanted to do it once I would use 2 part concrete floor coating. I would do 2 coats. Do one coat, then sprinkle on the sand then put another coat on top of that. For a sand sprinkler, get a quart can with lid and a 10 penny nail and punch about 30 holes on the bottom. put the can uprite on a board and fill the can 3/4 full and put the lid on. Use the can like a salt shaker, start with the can side ways for less sand more uprite for more sand. If your planning to add stiffening cleats or framing Put a coat of coating before you nail 2 pieces together. the wet bond will glue the stuff together and seal out the moisture.
The key with coating wood and making it last is the wood must be dry not just dry to the touch. Any moisture trapped under the coating will boil in the sun lifting the coating and letting more moisture in until the coating is compromised then everything falls apart. You want to use a prepaired epoxy coating so you get UV protection. Using straight epoxy you will have no UV protection. Same with your terminology of fiberglass which I assume is polyester resin and glass fiber. With out a gel coat or paint it will fail in the sunlight and expose everyone to raw glass fiber splinters.

[RogerDat]

[QUOTE=stevebaz;361187]If it were mine and I only wanted to do it once I would use 2 part concrete floor coating. I would do 2 coats. Do one coat, then sprinkle on the sand then put another coat on top of that. QUOTE]

I wondered about the 2 part basement epoxy paint. I have used that on concrete but never on wood. On the epoxy resin I was looking online at the west systems 105 but was thinking more of using it as a filler and sealer, no glass fiber.


When I did a dog walk (bridge with ramps) and a teeter totter I applied a lot of sand, then used compressed air to remove excess, then second coat as you suggest. Top was and still is pretty nice, edges started failing after first year, have gotten steadily worse.

Had not considered lack of UV resistance for both epoxy and resin. Can they be painted with good results?

[Richard Hayes]

For my money, absolutely nothing beats multiple coats of a good trwo-part epoxy for sealing plywood edges. Make sure you soak enough in to completely encapsulate the edge - 4 or 5 coats over a couple of days. The same mix can be used to coat and seal the working surfaces before they are painted. Cured epoxy is subject to UV degradation, and should be painted if it will be exposed to sunshine or weathering...

For antiskid, sailors use a very fine sand - almost a powder- that's stirred into deck paints before they are applied - I'm not sure if this approach would do what you (or the dogs) need done, but it works just dandy on wet fiberglass, which is very slippery stuff indeed...

WEST, MAS, Epiglass, Raka - any of the brand name epoxies are fairly equivalent, and should seal wood well. I have a 17' sea kayak kayak I built 12 years ago using 4 mm marine ply and EAST System epoxy - absolutely no delamination, checking, splits or other signs of problems with the wood.

[RogerDat]

Was hoping I would hear from the maritime provinces. :-)

Originally Posted by Richard Hayes

For my money, absolutely nothing beats multiple coats of a good trwo-part epoxy for sealing plywood edges. Make sure you soak enough in to completely encapsulate the edge - 4 or 5 coats over a couple of days....

Do you mean 4-5 coats on the edge, with less coats on the surface?

Originally Posted by Richard Hayes

For antiskid, sailors use a very fine sand - almost a powder- that's stirred into deck paints before they are applied - I'm not sure if this approach would do what you (or the dogs) need done, but it works just dandy on wet fiberglass, which is very slippery stuff indeed...

A local hardware store carried a product called Skid-Tec which I think is a version of the fine sand you mention. I have used that but had to supplement with a dusting of larger grit on top of the wet first coat. Followed by a second coat of paint. The dog tends to being going fast and must slow down enough on the downside to make contact with the bottom 42 inches. Elimination fault if they "fly off" the end.

Originally Posted by Richard Hayes

WEST, MAS, Epiglass, Raka - any of the brand name epoxies are fairly equivalent, and should seal wood well. I have a 17' sea kayak kayak I built 12 years ago using 4 mm marine ply and EAST System epoxy - absolutely no delamination, checking, splits or other signs of problems with the wood.

Do you recall what sort of pot life, hardener speed you used for that application?

Any process that can keep 4mm plywood exposed to water sound after 12 years sounds pretty good to me.

Newer A-Frames use a crumb rubber surface, it's great but sort of expensive $200 - $250 and if the wood fails it is generally money down the drain. One of the reasons I'm obsessing over doing the wood "right" is that cost vs the lower investment risk of paint with grit. I'll probably do the grit and paint, see how it holds up and add rubber later if wood seems to be holding up well.

Know anyone that has used MDO instead of marine ply?

I don't think I can go below 1/4 inch (6.3mm) and not have the board flex and bounce, which can make the experience scary for the dog. But I was thinking a couple of coats of epoxy should stiffen things a bit. Has that been your experience?

[Richard Hayes]

Re Question 1
You can use less coats on the flat surface, but more is better. Epoxy's two great features are that it is an excellent adhesive (unlike polyester resins), and that it creates a waterproof barrier. Remember, tho, that once that barrier is damaged by even a pinhole and water lodges beneath it, it is just as good at keeping it in contact with the wood as it was at keeping it out. I use four coats on the exterior ply on the kayaks, and three inside - I also cover the cockpit floor with FG cloth to prevent the epoxy being worn away by abrasion from dirt tracked into the boat. Another approach for surface toughness would be to mix an epoxy slurry about the consistency of ketchup, using fumed silica powder,then troweling that smoothly onto the surface - a single resin coat under that to saturate and bond and you'd be good to go. It sets up hard as flint...

Pot life - hardener speed: It varies by brand and temperature - the EAST is good for about 45 minutes with a medium hardener at room temp, IF you don't keep it in the restricted space of the mix container. Mixed epoxy sets up an exothermic reaction - it gives off heat as it cures - this speeds up the reaction, which gives off more heat, speeding up the reaction, etc.- - and the more confined the space, the faster this happens. To avoid this, I mix small batches - about a 1/2 juice can at a time, and make up a butter board about 18" square, cover it with several layers of construction plastic (so you can rip the used top sheet off and have a clean surface to work with), then pour the mixed epoxy on that; the larger surface area dissipates the heat, slowing down the reaction. You can get fast, medium and slow hardeners for most of the brand epoxies.

Re flex and bounce: coating both sides of the ply with multiple coats of epoxy will definitely stiffen it considerably. You can also cover the surface with a light 4 or 6 oz. glasscloth (cloth, not mat) saturated with epoxy, which really stiffens it. The 4mm ply we use is about 3/16".

And hey, Newfoundland isn't actually one of the maritime provinces - that's Nova Scotia, New Brunswick and PEI - we're in the Atlantic provinces, and in the middle of the North Atlantic ocean to boot! Truly one of the Last, Best Places....

[Ian G.]

The best product to seal plywood edges is CEPS Epoxy (Clear Penetrating Epoxy Sealer). CEPS is the consistency of water, a very thin 2 part epoxy that readily absorbs into the grain of wood and plywood to completely seal the surface. One caution in applying it to MDO, test a scrap before applying to your finished project. The glue on the paper overlay surface may react with the solvents in the epoxy and bubble or delaminate.

CEPS is available a specialty stores and online, one version of it is branded The Rot Doctor
CPES™-Wood based epoxy products to repair and resist wood rot.
Smiths Cold CPES Epoxy CPESCPT 2 Pint Kit - Amazon.com

and Industrial Formulators, their S1 Epoxy Sealer
Industrial Formulators

[RogerDat]

Originally Posted by Richard Hayes

........And hey, Newfoundland isn't actually one of the maritime provinces - that's Nova Scotia, New Brunswick and PEI - we're in the Atlantic provinces, and in the middle of the North Atlantic ocean to boot! Truly one of the Last, Best Places....

Oh I see it's a specific place. My bad. To us in the midwest maritime is anyplace that has all that marine boats and stuff, and where swimming means you are no longer at the top of the food chain.

[Richard Hayes]

Yep, we're small "m" maritime, as in boats and stuff, but capital A as in Atlantic..all clear now???

Swimming in the salt water around here about 10 months a year means you're very close to shuffling right off the end of the food chain as frozen food...lol...I usually have more merino wool under my drysuit when kayaking than the average merino sheep wears...

Don't mind me - just teasin' and tormentin' for a bit of fun, as we say...


BTW - Ian is spot-on re the CEPS - I've used Rot Doctor for wood rot repair on boats I've worked on, and it sure does seep into wood really well.

[RogerDat]

It seems obvious about the can trapping the heat and giving a shorter pot life. Never heard of it before. Good tip.

[stevebaz]

Buy the time and money and energy in looking for a composite solution you may be better off using plastic decking or individual plastic fence boards. These are designed for weather and other than the slick white fence pannels are nicly textured. There are various brands of this stuff.
Trex

[RogerDat]

Originally Posted by stevebaz

Buy the time and money and energy in looking for a composite solution you may be better off using plastic decking or individual plastic fence boards. These are designed for weather and other than the slick white fence pannels are nicly textured. There are various brands of this stuff.
Trex

Trex is pretty heavy about twice the weight of softwood. A-Frame is 9ft x 3ft on each side. I have to tip it over and stand it back up to mow. Or to take it apart to move it. Still it would be worth checking if they have any "sheet" material because your right it would not rot at all. Or maybe some sort of composite siding that would be thinner than deck or fence board.

Wonder how it would take glue or paint?

I am also checking on poly metal aluminum/plastic composite but no prices online. That would be a sandwich of alum/plastic/alum often used in signs. I have a feeling it may be expensive. Store bought A-Frames with that surface tend to be around $900 and up, wood sells for a few hundred cheaper.

I was just lucky to have a friend of a friend with a good aluminum frame, rotted deck, and moving to a condo on the west coast so I was able to pick up the used frame for a price I could afford. Normally the frame alone would be more than I could justify to DW to spend on my hobby.