# protecting new redwood with epoxy?



## Will22 (Feb 1, 2011)

You should probably consult with the manufacturer. In general, epoxies chalk badly with UV exposure, and applying them over prior coatings (which are not epoxies) can result in delamination, due to their aggressive adhesion. 

Epoxies are generally applied to non-porous substrates, and these coatings cure differently (chemically) from conventional water based and alkyd coatings (coalescence).


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## klaatu (Mar 9, 2015)

Will22 said:


> You should probably consult with the manufacturer. In general, epoxies chalk badly with UV exposure, and applying them over prior coatings (which are not epoxies) can result in delamination, due to their aggressive adhesion.
> 
> Epoxies are generally applied to non-porous substrates, and these coatings cure differently (chemically) from conventional water based and alkyd coatings (coalescence).


And it will be next to impossible to fix when it goes bad (and it will).
If this was a good idea, every paint company in the country would be selling it. Respectable paint companies spend millions in research to find the next big paint process. Don't second guess some of the best chemical engineers on the planet.


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## Gymschu (Dec 12, 2010)

Don't take this as gospel, but, I would think the epoxy would inhibit the wood's ability to "breathe" and move thus causing premature failure.


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## mako1 (Jan 7, 2014)

Very bad idea .A waste of time and money.

" wanted something to use on redwood fence posts where they go into the ground / concrete and board ends where it weather rots" 

First issue would be from moisture getting into the wood above where the epoxy is and getting behind it.


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## ric knows paint (Oct 26, 2011)

robertjmjrs said:


> anybody tried this? What do any of you think about using a clear epoxy coating. It is recommensed ok for wood but not wood floors because I think the clear is not UV proof.This epoxy is from Aeromarine products. It isn't cheap but it does go a reasonably long way because none of it goes off to evaporation. I do add about 15% acetone to get excellent wood penetration and believe that it probably does evaporate, but the product itself is low VOC, ok in Calif. and has no smell, unlike some horrible epoxys. There is a two to one mix of resin and hardener. This is the same stuff used on garage floors, on fabric to make fibreglas, and to pour thick clear countertops.
> I wanted something to use on redwood fence posts where they go into the ground / concrete and board ends where it weather rots. It dries so strong and penetrates wood so well that if two very wet pieces get pushed together, the flat parts become one piece. In taking them apart, one piece will lose about 1/4 in of wood ripped out. I am installing the third set of posts and many boards for my redwood fence around my house and want these to be my last. I ended up painting the entire new posts, 2 X 4 rails, and the redwood kick boards because they looked so beautiful. It takes painting over perfectly, and can be used to coat over a non loose existing paint.


Hey Rob't...

You're line of thinking isn't completely wrong...theoretically, an epoxy coating may be a great way to preserve buried boards. I don't think I'd apply it much higher on the post, than the portion that is buried though. The reasons are manyfold - (1) Epoxies are not UV Resistant...while a clear epoxy really has nothing to chalk from the surface, the film will still degrade from UV exposure...(2) this may or may not be an issue, but epoxies will yellow dramatically in UV exposure...(3) as Gymschu mentioned, epoxies absolutely will inhibit moisture transmission from the boards, which is OK if the boards are completely dry when applied (difficult to do), but any moisture that finds it's way into the board will not be able to escape through and epoxy coating..(4) I don't think everyone is convinced that this epoxy coating is going to be all that easy to repaint with conventional house paints or stains when that time comes. Epoxies can be difficult to paint over with anything but epoxies.

Having given you those warnings, it sounds like what you have described is a 100% solids product, which is good for going over existing coatings (no hot solvents to attack previous coatings), but can be bad as 100% solids epoxies are very rigid...inflexible. Wood is not rigid nor inflexible. Bad things can happen when immovable objects meet unstoppable forces, and the clean-up/repair can be monstrous. 

I think Mako, Gymschu, klaatu, and Will22, are all right-on with their warnings...this application may result in a greater future maintenance and on-going repair than you had ever considered. Good luck.


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## ric knows paint (Oct 26, 2011)

Will22 said:


> You should probably consult with the manufacturer. In general, epoxies chalk badly with UV exposure, and applying them over prior coatings (which are not epoxies) can result in delamination, due to their aggressive adhesion.
> 
> Epoxies are generally applied to non-porous substrates, and these coatings cure differently (chemically) from conventional water based and alkyd coatings (coalescence).


psst..Will - not to be nitpicky, but alkyds cure by oxidation, latex cures by coalescence.


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## klaatu (Mar 9, 2015)

ric knows paint said:


> Hey Rob't...
> 
> You're line of thinking isn't completely wrong...theoretically, an epoxy coating may be a great way to preserve buried boards. I don't think I'd apply it much higher on the post, than the portion that is buried though. The reasons are manyfold - (1) Epoxies are not UV Resistant...while a clear epoxy really has nothing to chalk from the surface, the film will still degrade from UV exposure...(2) this may or may not be an issue, but epoxies will yellow dramatically in UV exposure...(3) as Gymschu mentioned, epoxies absolutely will inhibit moisture transmission from the boards, which is OK if the boards are completely dry when applied (difficult to do), but any moisture that finds it's way into the board will not be able to escape through and epoxy coating..(4) I don't think everyone is convinced that this epoxy coating is going to be all that easy to repaint with conventional house paints or stains when that time comes. Epoxies can be difficult to paint over with anything but epoxies.
> 
> ...


I can envision the wood actually rotting away and a nice yellow shell of epoxy left behind.


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## mako1 (Jan 7, 2014)

+1 That's what will happen.
It will make a nice little sleeve to hold the water in.


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## klaatu (Mar 9, 2015)

mako1 said:


> +1 That's what will happen.
> It will make a nice little sleeve to hold the water in.


Maybe we should take this on Shark Tank.


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## robertjmjrs (Apr 1, 2015)

*Epoxy on redwood fences*

I do thank you all for the time spent in giving me input.

I was hoping that someone had actually used it on wood, even with maybe a protective UV coating over it.
I chose epoxy because it has been used on wood for marine applications and therefore might protect redwood from excessive ground moisture and rot. 

I checked with a chemical engineer who worked for a company who produced a higher voc product used in marine and in restoring wood in historical buildings. The engineer told me that if the epoxy were used as an undercoat on open wood and then covered with a high quality outside latex, the paint would last years longer. I used it that way on both sides of plywood sheathing I was replacing on my house.

That was about 5 years ago. The plywood was dry so I did not get the bubbles I got from the not totally dry redwood, but my sheathing application used a lot less paint and undercoat thus paying for the much more expensive epoxy. The application has so far stood up perfectly on both brand new and on existing panels, though UV protected. 

The current, much less expensive product I am using I am told will yellow over time in the sun. I guess I will find out what that will look like. Redwood stands up very well in the sun compared with most other woods. It decomposes where it has the most exposure over time to water. 

The ends of the boards seem to take the worse of it. The redwood posts don't see the sun in the ground, and I guess I was hoping that whatever the finish looked like from UV it might not be worse than the worn dark or white color redwood gets in the sun after a couple of years.

Redwood also has a very dark tannin like substance in it which I was hoping might help uv proof my application. With the acetone, the board and post ends suck up an amazing amount of epoxy. Just a hope. I was also just hoping that no one had experimented with it because it is not a natural choice. It has been much more expensive to buy than anything else people put on redwood fences (waterseal and cheap red paints, even older oil based paints which really do encapsulate the soft damp redwood).

Not only expensive to buy, especially in the past, but it has to be double mixed carefully in small batches, not a favorite of commercial painters, especially those who did all the trim on my house with it. They used it only because it lowered the number of coats of paint they had to use. Thank you all again. This was an experiment. Still appreciate any additional thoughts and input.


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## Nestor_Kelebay (Jun 17, 2008)

ric knows paint said:


> psst..Will - not to be nitpicky, but alkyds cure by oxidation, latex cures by coalescence.


Hmmm. Ric DOES know paint.

Robert:

Here is the part I think you're missing:

Supposedly rot resistant woods like Redwood and Cedar are largely misunderstood by the general public, and unscrupulous lumber dealers exploit this ignorance so that they can make a profit selling non-rot resistant wood products.

Every tree, whether it's a rot resistant variety like Redwood or Cedar or your regular run of the mill spruce or fir, has two regions within it's trunk; heart wood and sap wood.










The sapwood is the living part of the wood. Sapwood cells are full of a liquid which is mostly water, and there are passage ways between sapwood cells that allow moisture to move from each sapwood cell to the surrounding sapwood cells.

The heartwood occupies the middle section of the trunk, and is often considerably darker in colour than the sapwood. Heartwood consists of dead wood cells. As sapwood cells die to form heartwood cells, the tree deposits chemicals in these cells called "extractives" (IIRC) before sealing off the interconnecting passage ways between the heart wood cells and their neighbors.

It is these extractives in the wood that make it rot resistant. The extractives kill fungi and molds that try to feed on wood, thereby making the wood resistant to wood rot fungii.

Also, because the passage ways between heartwood cells are sealed off, heartwood is impermeable, and therefore cannot be pressure treated.

Now, it's these extractives that make the heartwood of Redwood and Cedar rot resistant. But the sap wood of Redwood and Cedar is not appreciably more rot resistant than any other species of wood. But, because that's not common knowledge, unscrupulous lumber vendors will sell redwood and cedar sapwood to people who believe that ALL Redwood and Cedar is rot resistant for a high price and that's how they profit from other people's ignorance. They never tell their customers that what they're buying isn't rot resistant, they just charge a high price for the wood and let the customer assume what he will about the wood.

Because heartwood cells are seal off from their neighbors, heartwood is impermeable, and can't be pressure treated. If it's the heartwood of Redwood or cedar, it doesn't need to be pressure treated because it's naturally rot resistant. However, in general, pressure treated sapwood of any species provides as good resistance to rot as the heartwood of any of the supposedly "rot resistant species". So, while building a deck entirely out of cedar or Redwood heartwood might give you the bragging rights of the nicest deck on the block, a deck built with pressure treated lumber will stand up equally well.

So, if you are saying that your epoxy PENETRATES into your wood, then we have a problem. It would not penetrate into heartwood, and the sapwood of Redwood and cedar aren't significantly more rot resistant than any other wood.

If you can return that redwood for a refund, I would return it and buy pressure treated lumber.


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## Nestor_Kelebay (Jun 17, 2008)

Robert:

The University of Massachusetts has a "Building & Construction Technology" program which leads to a Bachelor of Science Degree. Go to this web page:

http://bct.eco.umass.edu/

And click on the "Publications" link, then click "Publication by Title".

Scroll down until you find "Wood Myths; Facts and Fictions about Wood".

You can read it here:

http://bct.eco.umass.edu/publications/by-title/wood-myths-facts-and-fictions-about-wood/

It says:


*2) Cedar and redwood are rot resistant.*

Like fingernails on a blackboard, homeowners bubble, “I have cedar siding.” Don’t get me wrong cedar is my choice for siding too, but let’s get something straight. Not all siding, decking and trim made from cedar, redwood or other species famous for durability are in fact rot resistant. Only the heartwood of certain species is naturally decay resistant. Untreated sapwood of virtually all species has very little decay resistance. You can expect a short service life if you use sapwood in decay-producing exposures.
Large old-growth trees are a thing of the past. We now harvest smaller second-growth material that contains a high percentage of sapwood. Heartwood lumber is essentially unavailable in many species. Specify “all-heart” and you may be in for a dose of sticker shock. But if durability is important to your design, you should make heartwood part of your budget.
It’s difficult to precisely rate the decay resistance of heartwood for different species. But broad groupings have been made based on years of research and field performance. Common woods considered to be decay resistant include: all cedars, old-growth redwood, old-growth baldcypress, white oak, and locust. Heartwood of these species generally provide rot-free performance in an untreated state. Water repellent treatment is still a good idea on all wood exposed to the weather. Water repellent helps keep wood dimensionally stable.


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## ric knows paint (Oct 26, 2011)

Nestor_Kelebay said:


> Hmmm. Ric DOES know paint.
> 
> 
> yeah, well…so does Will - I was just ragging on him 'cause of his faux pas.


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## klaatu (Mar 9, 2015)

Nestor_Kelebay said:


> Hmmm. Ric DOES know paint.
> 
> Robert:
> 
> ...


Don't ever take stain or paint advise from someone who is selling you the wood or even a contractor using the bare wood. Why? BECAUSE IF THE WOOD LASTS FOREVER IT WILL PUT THEM OUT OF BUSINESS! That's one reason why contractors who build decks say "it has to weather for a year before you stain it" or even "just put Thompson's on it." They just want to build the deck and be done with it, and if it needs replaced in ten years it means another job for them. My last deck lasted 37 years using proper maintenance and my new one is 8 years old and the decking has been re-stained in Semi transparent ONCE! How? I listened to what a PAINT CHEMIST told me to do. 

Also, there is a difference between finishing marine wood and construction wood. Marine woods are exposed to extreme moisture conditions, and extreme measures are needed to keep the wood waterproof, especially below the waterline, and extreme UV protection is needed. BUT don't think for a moment that marine wood can be epoxied once and it will last forever! It WILL degrade to a point where it will need to be maintained, and that is a difficult process. I used to sell to a boat maintenance shop and guess what? Half their employees were there just to strip and sand failed coatings off the boats. If you have ever left a wooden boat sitting on the water for a few years you will know what I mean.

So if you would rather have to take an inordinate amount of time stripping and sanding epoxy off your redwood instead of just cleaning it every couple of years and putting a new coat of stain on it, then epoxy is the way to go.


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## klaatu (Mar 9, 2015)

Nestor_Kelebay said:


> Robert:
> 
> The University of Massachusetts has a "Building & Construction Technology" program which leads to a Bachelor of Science Degree. Go to this web page:
> 
> ...


Around where I live, a locust tree will barely hit the ground before an Amish guy will ask you for it. The absolute best wood for fence posts. Untreated it will last 40-50 years sometimes.

Also interesting to note that it was a bunch of people who got that degree from that school that developed the Storm System from California paints.


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## klaatu (Mar 9, 2015)

klaatu said:


> Around where I live, a locust tree will barely hit the ground before an Amish guy will ask you for it. The absolute best wood for fence posts. Untreated it will last 40-50 years sometimes.
> 
> Also interesting to note that it was a bunch of people who got that degree from that school that developed the Storm System from California paints.


 Excellent article btw Nestor. Thanks for posting it.


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## JourneymanBrian (Apr 1, 2015)

http://www.gov.scot/Resource/Img/46910/0039110.gif


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## JourneymanBrian (Apr 1, 2015)

This is a table based on the wood durability ratings from the EU, this particular table is from gov.scot.


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## JourneymanBrian (Apr 1, 2015)

"Homegrown" means grown in Britain, I believe.


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## klaatu (Mar 9, 2015)

JourneymanBrian said:


> "Homegrown" means grown in Britain, I believe.


Now that has a totally different meaning were I am!


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## robertjmjrs (Apr 1, 2015)

*epoxy on redwood fence structural members*

I really do appreciate you all taking the time to help educate me. I was aware of the difference between heartwood and the white (common). Where I live there are only a few specialty places that sell the very expensive heartwood structural lumber; most sell common. I have been able to handpick all heartwood which might have a sliver of white here and there. I did get fooled on a couple of of the posts though because I later noticed that they are staining some of the common red so it makes it very difficult to tell the difference. You are right about the penetration; The ends take up about 8 or 10 times as much epoxy as the flat grain, except around the knots. Please understand that this is a fence, not a deck. I have a 27 year old redwood deck made with 3 sides perfect 2 by 6's and mostly close grain redwood. It has held up beautifully, most boards are crack free except for the ends away from the house. They all have multiple cracks going back about 6". The other end which buts up against a plastic strip against the house is almost crack free. This made me wish I had sealed the open end with something that would penetrate and worked. 
Note that I did not use the epoxy on the fence boards except the kick boards. If the epoxy goes south it is only the frame (mostly the rails and kick boards which will show it. I guess time in the sun will tell. I guess I was hoping that someone knew of a clear product I could put over the epoxy to UV protect it. In reading the specs on the epoxy it said that this type was very strong, but had some "give" to it so it would flax and not crack or shatter easily. One thing which pushed me beyond just coating the bottom 4 feet of the posts was how beautiful the dried epoxy made the redwood look. Though it darkened it a bit on most boards, it really brought out an intense red color.


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