# Soaking End Grain in Polyurethane



## MikeyPiano (Sep 13, 2020)

I decided to try soaking the end-grain on some kitchen table feet. I'm happy with the way it's drinking up the polyurethane. This is what it looks like after 1-2 minutes. Do you think that's all I'll need to do for the bottom end-grain or is there another step I should take? This table will be used outdoors, under a BBQ pavilion.

notes:
- legs are 1.5×1.5 inches
- there's a light chamfer on the feet
- soup lids from Chinese take-out


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## Lazyman (Aug 8, 2014)

My guess is that the wood is absorbing mostly the oil base and less of the resin.

What is your goal in doing this?


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## woodbutcherbynight (Oct 21, 2011)

> My guess is that the wood is absorbing mostly the oil base and less of the resin.
> 
> What is your goal in doing this?
> 
> - Lazyman


I wonder same thing. For outside work such as this I use clear caulk or silicone and let cure for a week. Seals the ends up and gives a measure of protection from wicking of water up into the wood.


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## bigblockyeti (Sep 9, 2013)

I would be inclined to install plastic nail on feet to keep from abrading away any film finish on the end grain when it's slid across the ground and to elevate it from even the slightest water to avoid wicking any up.


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## John Smith_inFL (Dec 15, 2017)

that is probably 99% more than most of us do for interior projects.


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## MikeyPiano (Sep 13, 2020)

> My guess is that the wood is absorbing mostly the oil base and less of the resin. What is your goal in doing this?
> - Lazyman


That's interesting about the oil vs. resin, I'll check to see what happens. My goal is to protect the feet from wicking up water.

The table will be in hot humid weather all year round. It might also get dragged around and occasionally placed on wet grass/dirt/concrete.


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## MikeyPiano (Sep 13, 2020)

> For outside work such as this I use clear caulk or silicone and let cure for a week. Seals the ends up and gives a measure of protection from wicking of water up into the wood. - woodbutcherbynight


Thanks for the tip, I'll look into the caulk and silicone. What are the benefits over polyurethane?


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## MikeyPiano (Sep 13, 2020)

> I would be inclined to install plastic nail on feet … - bigblockyeti


Definitely, nail on feet after the polyurethane is dry.


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## AlanWS (Aug 28, 2008)

That should help to protect the feet from moisture. As noted above, the usual approach is to attach a foot to keep the wood off wet surfaces. I have used very thin epoxy that soaks in and hardens without any need for evaporation (System Three rotfix) and it has worked well for years outside.


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## Lazyman (Aug 8, 2014)

One problem with putting any film finish on outdoor furniture it that it will eventually crack. When that happens water will seep in and ultimately get trapped under the finish which will cause it to mildew. If it is protected from sun and rain it will take longer for that to happen but it will eventually happen. Refinishing an old cracked film finish usually requires you to strip the old finish. IMO, It will actually do better to have a non-resin exterior oil based finish that can breath so that any water that does get absorbed will dry quickly but you will have to refresh the finish fairly often depending upon how exposed to the elements it is. An oil finish can usually be refreshed with light scuff sanding and a fresh coat. If the table will usually be sitting on a hard surface and just occasionally sitting on soil, I would not worry too much about the legs but some feet or end caps would not hurt.

If you do opt for something like a poly finish, make sure that you pick one that is a spar finish. They are usually more flexible and will resist cracking longer.


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## DS (Oct 10, 2011)

Why not add adjustable glide feet to the bottom to keep it level and off the ground?


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## SMP (Aug 29, 2018)

I second what DS posted. As pretty much no surface, outside especially, is flat. Plus keeping the bottoms from dry rotting.


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## newwoodbutcher (Aug 6, 2010)

I'm no expert but I think sealing the bottom of an outside wooden leg will lead to faster wood rot by holding water in the leg instead of letting it drain.


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## kelvancra (May 4, 2010)

I think it's an excellent ideal. I did this off and over the last forty years, but thinned the poly as much as 30% or so.

Since items I did this with sat in front of a well used wood burning stove, for several decades, without cracking and splitting from moisture loss, it should be obvious the items didn't gain much moisture either.

The poly was so penetrating one six inch slab, a gallon in, started showing wet spots on the bottom, which were discovered only when I dropped my brush and bent down to pick it up. AND, if it was only the oil penetrating, the top would have been clear coated with resin. It wasn't.

I love penetrating coats without built up surface coats. I've never had one crack, like I have surface coats.

If you were concerned about wood shifts with moisture gain and loss, bend the poly formula with some more hardening oil, to bring it more to a long oil finish, which is what is used for nautical finishes. Long oil finishes are less durable, but more flexible.

I do not believe this method would, in any way, speed rot. This is nothing like burying a post in the ground and surrounding it with concrete [which holds moisture in]. It is like what I do with plywood and particle board counter top bases around a sink, to stop unintended moisture contact from penetrating.

ALL the above aside, when I build steps and things, I slip a piece of granite tile under the 2x's to minimize contact with the sidewalk or ground. In that vein, what DS suggested would be a good idea.


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## MikeyPiano (Sep 13, 2020)

*UPDATE #1*
Here's what the feet look like after soaking in polyurethane. I'm satisfied with this, mainly because it's basically labor free (what a bargain!). Just let it soak overnight and by morning it's penetrated the end-grain and there's a thick coat to boot - better than I would have gotten doing it by hand. I'll sand it down and manually poly the rest of the wood. Nail-on-feet are coming in the mail. FYI - regarding the end-grain soaking up the oil vs. the resin - the end-grain sucked up 90-95% of the poly I put in those plastic covers, so hopefully that's a good sign.










*UPDATE #2*
I checked into the silicone caulk vs. polyurethane. Apparently, silicone is very effective on most other materials - except wood and paint (which is I guess where polyurethane comes in). Also most silicone caulk works better in warm weather, while special forumulations are needed when it's colder.


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## becikeja (Sep 12, 2010)

I recall an episode of the wood whisperer where he coated the bottom of outdoor furniture legs with epoxy. Have never tried it myself.
Unfortunately only time will tell how this works out.


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## Lazyman (Aug 8, 2014)

I am still skeptical that the resin is being sucked very deeply into the grain. Remember that up to 75% of the mixture by weight are volatile solvents that evaporate, leaving the resin behind on the surface during normal application. These lighter solvents are also more likely to be absorbed into the end grain than the resin. If I recall, most poly finishes not intended for floors are less than 15% resin solids by weight and since the resin is more dense than the solvents, they will be less than that by volume. With the amount of the resin sitting on the surface and a significant amount of the solvent being absorbed or evaporating, leaving more resin than solvent behind, only 90% remaining sounds like about what I would expect.

If you have ever done an experiment in school involving paper chromatography, you will remember that lighter elements will rise higher on the paper and I think that you would see a similar result here. Lighter materials will rise higher with capillary action and the type of wood, density, the size of the pores, etc. will all affect how deep the resin and other components will be absorbed, especially since the it looks like you have the end grain sitting directly on the saucer which would seem to limit uptake into the end grain.

An interesting experiment would be to do this with a cutoff. After soaking, wipe it off so that it doesn't have a super thick amount sitting on the surface. Weigh it before and after the soaking and then again a few weeks later to see how much net weight it gained after it has cured and the solvents have evaporated. Then cut it in half and look at it under magnification to see just how far the poly penetrated.

Anyway, label me a skeptic.


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## LeeRoyMan (Feb 23, 2019)

Good job Mikey,
No matter what got sucked up, I believe you have added another layer of protection.


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## Davevand (Feb 10, 2016)

I made an adirondack chair out of cheap white wood from the big box store. I sealed the end grain of the feet with construction adhesive, used a putty knife and put a thin layer on. I also primed and painted all the pieces before I put it together. It lasted for ten years out in the weather before it rotted away. The part that rotted was where the seat met the back, water and debris collected there causing the rot


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## kelvancra (May 4, 2010)

Lazyman, I think there is truth to what you say, but we have to factor in the wood being used too. Take certain oaks, for example, you can tip a 4×4 on end, pour thin oil in it and it will drip out the other end.

Just sticking a board in brush on poly, which is far from a 75% solvent mixture, would result in some wicking, since the poly tends to wick to the next dry area. Key is, keeping it wet. The minute you let it dry, you've stopped the process from progressing.

As to the oil wicking, also keep in mind we are talking about hardening oil and not just any hardening oil. It is polymerized, so more durable and water resistant that straight BLO or tung oil.

In the end, we'd have to do so weigh experiments to really know what was going on. That said, when I put a gallon of thinned poly on wood and it, immediately disappears, the solvent, obviously, is not all gassing off. Everything, solvent, oil and resin is going into the wood.

Even painting an old house on the ocean, I've watched latex disappear. Clearly, it was going somewhere other than into the air [though I was using an airless to get the paint up on the wall]. Since I'd bought pastel mis-mixes in the suppliers high end paint, it, mixed, was gray. In the end, I put about thirty gallons on a house that most would have put only fifteen on. Before I started, you could put your finger through some of the shakes, they were so thin.

My stance was, contrary to self proclaimed painting experts, if the paint soaked in, it was just that much more protection the house would enjoy. My money is on that I have that house with it's thirty some year old paint job another twenty or more years. That's food for thought.


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## justaguy (Jan 21, 2020)

I was about to add that I use a coat of West epoxy for that atsk


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## OSU55 (Dec 14, 2012)

> My guess is that the wood is absorbing mostly the oil base and less of the resin.
> 
> What is your goal in doing this?
> 
> - Lazyman


Oil based poly is a completely dissolved solution. Whatever ratio of volatile/nonvolatiles will soak into the wood to the same depth and leave the solids behind after evaporation. Water based finishes are a different animal, being a mixture and I'm not sure how the resin vs water uptake would be.

Provided the OP used an exterior poly this is an excellent method. In addition putting some type of tips to elevate the leg tips off the surface would be the best solution.


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## splintergroup (Jan 20, 2015)

Just for grins, a number of years ago I made a trivet from end grain red oak for the MIL. Basically a small cutting board style about 8"x8" and about 3/4" thick. I place it flat into a shallow pan of thinned poly about 1/4" deep. Within about an hour, the mix was beginning to ooze from the pores on the top surface. Left over night, it appeared completely saturated. 
I had left it upside down on some paper towels to drain off, but forgot about it for several weeks after which time the paper towels were basically glued to the surface. Sanding took care of that and it sure had the feel/appearance of something that had been poly finished on all surfaces. I never really thought about if the interior ever cured.


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## kelvancra (May 4, 2010)

As I posted above, where is the polymerized oil AND resin going when they are all gone? They are NOT evaporating. That leaves only that they end up absorbed into the wood, filling the cells.

If latex paint can soak into wood and disappear, a bit of resin only polymerized oil would have even less trouble, it would seem.

Just for reference, I've saturated the outer layers of 2x's milled into 2'x5' picture frames and, forty years later, they're still prime. What's his nose (Fletchner- nationally known finish expert (rightfully so, but….)) and I butted heads on this issue about 20 years ago. He claimed penetration was a Varithane ad promotion. I called bullsh_t on him.

Today, we KNOW wood stabilization is real and works. You could bury a piece of stabilized wood in the garden, dig it up a decade later and it would still be fine.


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## therealSteveN (Oct 29, 2016)

You could easily do a test using oil based Poly, and some scrap. Let it sit 12, 24, whatever or until a certain amount of the poly was gone from your petri dish.

Allow time to dry, at least what you could see, and start slicing off chunks till you get just wood. Even if you got 1/2" in, and then used the T nut, and Elevator bolt idea to lift it off the ground, it would be more protection than doing nada.

I am thinking it will all absorb.

Interesting post.


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## MikeyPiano (Sep 13, 2020)

*Final Update*: 
With the screw-in leveling feet installed. Notice how thick the polyurethane is on the bottom. The rest of the legs got 3 coats of poly, but that bottom layer of poly is really thick. Anyway, the table is in service now, so it's out of my hands. Thanks for the all the discussion!












> > - DS


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## BuckeyeDennis (Mar 24, 2019)

I'll wager that the zinc-plated steel rusts many years before your poly-soaked end-grain wood rots!


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