Epoxy for cement contact old wood

[JHZR2]

I have two old garage doors, which I’m refurbishing per discussion in other threads. I think this question/discussion is worthy of standalone for others who might have old wood that sees occasional moisture and that folks want to keep protected in good shape.

One door I had to redo the bottom. Years of water and splash just made the panels and some of the connecting bits too rotten.

The other one is salvageable. The bottom section is ok (will need to replace a few of the panels), all the main wood is pretty sound. The bottom has been unpainted for a long time, and there’s some degradation along the bottom. I don’t have a picture unfortunately.

It’s probably some form of “dry rot”, I don’t know. But it’s sort of just like old grey wood where some of the softer fibers are more sunk in. I don’t know how else to define it.

Anyway, I want to seal things, make it all right and weatherproof, etc. I was thinking to perhaps do some sort of skim coat of an epoxy on the bottom of the door, to stabilize everything, provide a barrier to the contact with the cement, and fill in a few spots where the bottom is uneven.

I’ve seen DIY where people making live tables pour epoxy into holes in wood to get a hard cured material that will last. I don’t have holes or voids, just this softer wood that has seen if not a century, probably at least 75 years of weather. I just want to strengthen it up before paint.

Any thoughts on doing this? I’m thinking a low viscosity, relatively fast cure epoxy, brushed on them sanded after the cure.

I know sometimes bondo is used on wood rot. But that’s to fill big gaps. I’m just looking for a bit of weather protection and sealing the surface.

Thoughts??

 

[doitmyself]

I have just a one-time experience with wood rot repair. Are you aware of the kits available for this?

I used the Minwax 2 component kit to repair some exterior window trim. It's o.k. after about 5 years. It consists of a liquid that penetrates and "tightens up" the wood and a 2 part bondo-like product.

High Performance Wood Hardener | Minwax®

Minwax® High Performance Wood Hardener is a quick-drying liquid formulated hardener to strengthen, reinforce, and repair decayed or rotting wood.

www.minwax.com

Wood Filler - Wood Repair & Wood Adhesive| Minwax®

Minwax® High Performance Wood Filler is a two-part wood filler for filling gouges, holes and damaged areas in wood and acts as a wood adhesive.

www.minwax.com

Lots of other products that I have no experience with. It seems that these marine type, low vis, penetrating epoxy products would be superior.
https://www.jamestowndistributors.com/product/product-detail/97636?promo_name=penetrating-epoxy

 

[vavavroom]

They make wood hardener/stabilizer that penetrates deep into the wood. Minwax sells it by the pint.

 

[wrcsixeight]

Letting the wood soak up as much resin as it wants will greatly harden and seal it.

Epoxy is not winter temperature friendly, cure wise. Its really best if it never falls below its minimum cure temperature for the initial 8 hours.
While it eventually will seem to harden up if it falls below this on the initial 12 hour period, it does not seem top have the bond strength or impact strength as when it is kept above say 65f the whole initial 8 hours.

I often mix in milled fiberglass powder to epoxy when more strength is needed, and wood flour if I need to thicken it into a bondo like consistency.

When applying thickened epoxy, make sure it is applied to a porous surface that has soaked up all the unthickened epoxy it wanted first, or the material can suck the epoxy out of the thickened epoxy causing a poor bond.

If you are doing this in place, you can form fit the bottom of the door to the concrete surface below, if that is desirable. Epoxy does not stick to plastic sheeting, so you could in theory achieve a near perfect seal by painting on epoxy thick a few times in the initial cure, then mix another batch of epoxy, thicken it will milled fiberglass and wood flour until peanut butter consistency, use a drywall knife to apply to bottom of the door, then close the door atop the creaseless plastic, then fair it out.

Epoxy does not like long term sunlight exposure, but you say it is going to be painted. The Amine blush formed when epoxy cures in high humidity can repel Paint causing fisheyes/ orangepeel It is water soluble though,. scrubbie sponge soap and water and a good rise. .Skuff the cured epoxy with 220 grit or red scotchbrite before applying paint.

I collect wood 'flour' from my belt sander's catch bag, usually from a soft wood like cedar or redwood, but it can be purchased.

Wood Flour, 32 fl. oz., Quart

Supplier of carbon fiber fabrics, fiberglass, epoxy resins, core materials, polyester resins, surfboard blanks and other supplies for working with composites.

fiberglasssupply.com

Quart, 1/32" Milled Glass Fiber

Supplier of carbon fiber fabrics, fiberglass, epoxy resins, core materials, polyester resins, surfboard blanks and other supplies for working with composites.

fiberglasssupply.com

When mixing epoxy, one should strive for perfection on parts A and B ratio. If one is more than a few % out it will still cure, but could be soft or not bond very well. I find mixing by weight with a digital scale leaves little room for error, compared to mixing by volume. Make sure the mixing stick can get the corners of the mixing cup and that it is truly thoroughly mixed. Do not treat epoxy like 'fiberglass' resin, which is polyester resin and the MEK hardener and too little just means more time to cure. DO not alter epoxy ratio for temperature.

Clean application tools with distilled white vinegar. No acetone or vile solvents needed.
I like rolling on epoxy, with a thick knappy roller, slowly, so as to not introduce air bubbles. Dont try and spread it thin like paint. no more than 2 revolutions of roller with minimal pressure, then grab more epoxy from tray. If multiple coats required/desired, best to apply the second coat while first is still slightly tacky, for a chemical bond and no in between sanding. Temps above 65f and low humidity are best.

Porous wood can blow bubbles as the epoxy heats. Best to have wood heated and falling temperatures when applying thick epoxy, when possible

The bartop epoxies are pretty thick, most recommend a sealing coat before applying, but thick does not penetrate deeply.

Denatured alcohol can thin out epoxy, Xylene is likely better.

I thinned JB weld to seal my radiator tubes where them were seeping from bottom tank/tube region. I Did not heave denatured alcohol or everclear or xylene and used 70% isopropl alcohol. 3 cross country trips later no coolant loss.

Epoxy, like the prices of most everything has gone up a lot recently.

Apex Quickset CLEAR Surfboard Epoxy Resin | Fiberglass Source/Surf Supply

Clear epoxy surfboard and marine resin, is a fast epoxy resin system. Our 2-to-1 mix of surfboard and marine epoxy resin works well on all fiberglass reinforcements.

fiberglasssource.com

This outfit is in NJ:

Fiberglassing Equipment for Composite Fabrication - Surf, Boat, Auto

Glass Reinforced Plastics (GRP) is fiberglass cloth saturated with epoxy or polyester resins to create very strong and light weight composite structure. Uses include Surfboard Glassing, Boat Repair, Fiberglass Molds, Fiberglass Tooling, Aviation and Aerospace, Automotive, Boats and Marine...

greenlightsurfsupply.com

HAving worked a bunch with west systems epoxy, and other brands, I much prefer other brands.

System 3 resins are $$$ but some can be used in temps as low as 35f.

 

[JHZR2]

Letting the wood soak up as much resin as it wants will greatly harden and seal it.

Epoxy is not winter temperature friendly, cure wise. Its really best if it never falls below its minimum cure temperature for the initial 8 hours.
While it eventually will seem to harden up if it falls below this on the initial 12 hour period, it does not seem top have the bond strength or impact strength as when it is kept above say 65f the whole initial 8 hours.

I often mix in milled fiberglass powder to epoxy when more strength is needed, and wood flour if I need to thicken it into a bondo like consistency.

When applying thickened epoxy, make sure it is applied to a porous surface that has soaked up all the unthickened epoxy it wanted first, or the material can suck the epoxy out of the thickened epoxy causing a poor bond.

If you are doing this in place, you can form fit the bottom of the door to the concrete surface below, if that is desirable. Epoxy does not stick to plastic sheeting, so you could in theory achieve a near perfect seal by painting on epoxy thick a few times in the initial cure, then mix another batch of epoxy, thicken it will milled fiberglass and wood flour until peanut butter consistency, use a drywall knife to apply to bottom of the door, then close the door atop the creaseless plastic, then fair it out.

Epoxy does not like long term sunlight exposure, but you say it is going to be painted. The Amine blush formed when epoxy cures in high humidity can repel Paint causing fisheyes/ orangepeel It is water soluble though,. scrubbie sponge soap and water and a good rise. .Skuff the cured epoxy with 220 grit or red scotchbrite before applying paint.

I collect wood 'flour' from my belt sander's catch bag, usually from a soft wood like cedar or redwood, but it can be purchased.

Wood Flour, 32 fl. oz., Quart

Supplier of carbon fiber fabrics, fiberglass, epoxy resins, core materials, polyester resins, surfboard blanks and other supplies for working with composites.

fiberglasssupply.com

Quart, 1/32" Milled Glass Fiber

Supplier of carbon fiber fabrics, fiberglass, epoxy resins, core materials, polyester resins, surfboard blanks and other supplies for working with composites.

fiberglasssupply.com

When mixing epoxy, one should strive for perfection on parts A and B ratio. If one is more than a few % out it will still cure, but could be soft or not bond very well. I find mixing by weight with a digital scale leaves little room for error, compared to mixing by volume. Make sure the mixing stick can get the corners of the mixing cup and that it is truly thoroughly mixed. Do not treat epoxy like 'fiberglass' resin, which is polyester resin and the MEK hardener and too little just means more time to cure. DO not alter epoxy ratio for temperature.

Clean application tools with distilled white vinegar. No acetone or vile solvents needed.
I like rolling on epoxy, with a thick knappy roller, slowly, so as to not introduce air bubbles. Dont try and spread it thin like paint. no more than 2 revolutions of roller with minimal pressure, then grab more epoxy from tray. If multiple coats required/desired, best to apply the second coat while first is still slightly tacky, for a chemical bond and no in between sanding. Temps above 65f and low humidity are best.

Porous wood can blow bubbles as the epoxy heats. Best to have wood heated and falling temperatures when applying thick epoxy, when possible

The bartop epoxies are pretty thick, most recommend a sealing coat before applying, but thick does not penetrate deeply.

Denatured alcohol can thin out epoxy, Xylene is likely better.

I thinned JB weld to seal my radiator tubes where them were seeping from bottom tank/tube region. I Did not heave denatured alcohol or everclear or xylene and used 70% isopropl alcohol. 3 cross country trips later no coolant loss.

Epoxy, like the prices of most everything has gone up a lot recently.

Apex Quickset CLEAR Surfboard Epoxy Resin | Fiberglass Source/Surf Supply

Clear epoxy surfboard and marine resin, is a fast epoxy resin system. Our 2-to-1 mix of surfboard and marine epoxy resin works well on all fiberglass reinforcements.

fiberglasssource.com

This outfit is in NJ:

Fiberglassing Equipment for Composite Fabrication - Surf, Boat, Auto

Glass Reinforced Plastics (GRP) is fiberglass cloth saturated with epoxy or polyester resins to create very strong and light weight composite structure. Uses include Surfboard Glassing, Boat Repair, Fiberglass Molds, Fiberglass Tooling, Aviation and Aerospace, Automotive, Boats and Marine...

greenlightsurfsupply.com

HAving worked a bunch with west systems epoxy, and other brands, I much prefer other brands.

System 3 resins are $$$ but some can be used in temps as low as 35f.

This is great info. I like the idea of setting it up to match the very old concrete beneath. Understood on letting it soak some in thickened epoxy first. That’s really my aim.

These photos aren’t great but they give some idea of the original old wood.

 

[wrcsixeight]

Soft and rotted wood can be a bit frustrating, for me, as I imagine what if the epoxy does not get behind a piece of loose wood, yet removing the rotted wood can leave huge gaps which then have to be filled, and if there is a lot then I generally want to saw it off and adhere new wood, and before I know it a small project turns into a complete rebuild making it stronger and better than it was originally built when that is not really needed.

Big masses of epoxy, exotherm, heating up and expanding, which then shrinks afterwards, perhaps making the repair attempt appear OK, but in reality a huge chunk of epoxy could fall out or just cause water to wick under and over it. This makes letting the wood drink up as much unthickened epoxy as it wants, then applying the thickened epoxy before any blush can form and inhibit secondary bonding, advantageous.

All secondary bonding should try to be avoided, but of course is not always possible. When not possible to achieve the chemical bond, any blush needs to be removed and then the surface roughened for mechanical tooth. Many epoxies will claim to be blush free. One should take this claim as a partial truth.... being less prone to producing lots of Amine blush. Dew and moisture forming on such epoxy within 24 hours, perhaps more depending on temperature will have the surface turn white, and this is not so easy to remove.

If you really like the forming the bottom to fit idea, you could in theory make a 1/2"+ tall plastic dam on both sides of the closed door and close it on poured unthickened epoxy, and you will be surprised at how much epoxy is wicked inside the wood.

Microballons mixed into the epoxy will make it lighter and easier to sand when making one's own 'bondo' if applying with a drywall knife or bondo spreader.

One can also drill shallow holes at opposing angles if there is fear that the epoxy will not bond or bond strongly enough into the substrate.

One odd shaped surfaces, one can use saran wrap or freezer bag plastic to form the epoxy into shape for minimal post sanding.

Epoxy, as opposed to polyester resins, slowly harden, and can be shaped as they thicken. Polyester resins just tend to be workable, then not, in a matter of 30 seconds or so.

There's lots of great information on working with epoxy in System 3's 'The epoxy book'

About the System Three Epoxy Book

Welcome to The Epoxy Book. Here you will find a wealth of information regarding the use of epoxy in boat building, wood working, rot repair and more!

www.systemthree.com