Penetrating epoxy: legend or myth?

[saywhatthat]

Getting ready to do a trailtop component woody looking into different Epoxy's .found this a bit interesting . Penetrating epoxy: . Like the part about heating the wood first.
https://www.epoxyworks.com/index.php/pe ... #more-7278

[MickinOz]

I've heard it before. No solvent based coating that relies on the solvent evaporating can be truly waterproof due to the solvent leaving micro-pores behind as it finds its way to the surface,

This article is very interesting.
https://www.branchingoutwood.com/blog/p ... ane-finish
It references US Government research, so I guess it must be one of the more believable articles to be found on the internet.
Based on this article, my topcoat on the teardrop is likely to be exterior grade enamel house paint from reputable company.

The referenced chapter on protecting wood is here.
https://www.fpl.fs.fed.us/documnts/fplg ... 3/ch15.pdf

I've only skimmed it, but one thing of note: All those people who say you should coat the interior of your plywood, the bits that'll never be seen, are correct. Back-priming is a recommended process.

[John61CT]

Fully encapsulated best of all.

More coats the better.

What some call overkill is just good enough for others.

[saltydawg]

The flaw with more coats of penetrating epoxy the better is flawed in one way.

Penetrating epoxy only needs one coat, but it needs to be a heavy coat, like keep putting it on until it stops soaking in then put more. The flaw with multiple coats is the first one only goes in so far in to the wood then seals it. You dont want that, you want it to keep soaking in until it cant any more, saturate the wood completely with the first coat.

If you only seal one side the other can still get wet. Also putting the body together then wetting it with what ever is flawed as your joints will prevent the sealer from getting to the end of the grain or layers of ply. Ideally you build it, then take it apart and seal every side, edge and surface then put it back together.

Now total encapsulation with epoxy is another another story.

Or build from foam and either glass it or skin it with fiber glass sheet and have no worries about rot.

[GPW]

We’ve been using “ the Mix “ for many years (40+) to waterproof wood … Cheap , effective , really soaks in and protects wood … Tested on doors , fenceposts , sheds … and TRAILERS …

[tony.latham]

For sealing wood, I use Raka's thin-set resin with their slow hardener. There is no added solvent and it soaks in nicely to the wood and really plasticizes the surface. I've done this with the teardrops I have sheathed with aluminum. I also seal the galley floors and the bottom of the 'drop.



I think penetrating epoxy probably has a place for repairing rotten wood.



I do recall someone on this board using a penetrating epoxy (Rot Doctor) to seal luan and the solvents caused the glue to disolve and it delaminated.



Tony

[MickinOz]

We’ve been using “ the Mix “ for many years (40+) to waterproof wood … Cheap , effective , really soaks in and protects wood … Tested on doors , fenceposts , sheds … and TRAILERS …

I have a theory about that.
I note that the article I referenced counts the waterproofing ability of polyurethane as quite high.
I think that is because of the way it cures.
Sure the solvent carrier needs to evaporate, but I believe the polyurethane cures by combining with water molecules.
For example, I note there is no shrinkage and perhaps, if I could measure it, a little swelling when my polyurethane caulk sets.
So maybe the micro pores are filled by the poly.

[Socal Tom]

Last time I checked, plywood was held together with glue. Glue's are dissolved by different solvents, some glues can be dissolved by water, some by petroleum solvents. I would tread carefully.

[MickinOz]

Last time I checked, plywood was held together with glue. Glue's are dissolved by different solvents, some glues can be dissolved by water, some by petroleum solvents. I would tread carefully.

That's one of the reasons I was a bit picky about the plywood I bought.
Had to have that stamp that says A-Bond.
BTW, when I use the word "solvent" in this context, I mean water as well. Because it is a solvent, too.

[GPW]

The Foamie guys have a saying … “ Test Everything for yourself “ !!! The only way to know ( for sure) if it’s correct for your purpose .

Here in New Orleans , everything Rots … and fast too , so tests go quickly … Much different than other places that are much drier … And here , if it doesn’t rot , it gets moldy …

[JuneBug]

For sealing wood, I use Raka's thin-set resin with their slow hardener. There is no added solvent and it soaks in nicely to the wood and really plasticizes the surface. I've done this with the teardrops I have sheathed with aluminum. I also seal the galley floors and the bottom of the 'drop.

I think penetrating epoxy probably has a place for repairing rotten wood. Tony

To clarify, the wood in the picture was eventually covered with aluminum after being treated with the resin, or was the treated plywood the final exterior finish?

[tony.latham]

For sealing wood, I use Raka's thin-set resin with their slow hardener. There is no added solvent and it soaks in nicely to the wood and really plasticizes the surface. I've done this with the teardrops I have sheathed with aluminum. I also seal the galley floors and the bottom of the 'drop.

I think penetrating epoxy probably has a place for repairing rotten wood. Tony

To clarify, the wood in the picture was eventually covered with aluminum after being treated with the resin, or was the treated plywood the final exterior finish?

There she is.

Tony

[noseoil]

Elmer's glue works pretty well on things for bonding & acting as a moisture barrier. I've used it for stabilizing adobe in our house in Tucson. Mix it 50:50 for an exposed wall, spray enough to soak into the surface & let it set for 24 hours. Too much in one spot will cause the wall's surface to slump & move. Just enough & it's pretty good for keeping the wall in place, sealing it & hardening the surface. It's not an exterior finish, but it makes a difference when going from raw dirt to a hardened surface for finishing.

I put this in here because there's more than on way to skin a cat. Climate & weather play a large role in how well things last. Adobe in New Orleans would not be a good way to build, straw bales would also be a bad choice, unless you want compost for your insulated walls & a roof that's settling over time. Urethane will keep the water out of walls, epoxy is better, but neither one is worth a damn if it is used improperly or mixed wrong.

I put 2 coats of urethane on our trailer both inside & out, top & bottom, it's holding up fine still. The aluminum will allow moisture to get under the wall, yes, but the urethane seems to do the job well enough for things to hold together over time. A good epoxy job will last about for ever, but not if there's UV involved. UV will eat epoxy. The sun, moisture, termites, rot, mildew, all will affect wood, but how well things are put together will determine how they last. How they are stored also affects things, lots of variables here to consider, time & money too...