Wood Repair

  • Which product do you recommend for wooden support beam repair?

    Repairs in a wooden support beam that has lost its structural integrity are beyond the capabilities of epoxy filler putties and adhesives alone.  Additional materials, methods, and expertise must be accessed to complete a successful and safe beam repair of this type.

    For cosmetic repairs please watch our beam repair video and/or print the article below it.



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  • Will UV light affect System Three epoxies?

    Products based on room-temperature curing epoxy resins have poor resistance to UV or sunlight.  Depending on the severity of exposure, the surface will become dull, then cloudy, finally chalking breaking down sometimes in less than a year's time.

    We recommend overcoating with System Three Marine Spar Varnish or WR-LPU, both thin-film coatings which contain UV absorbers to protect the epoxy and the surface underneath from the sun.

    Please see the attached white paper on Clear Finishing Outdoor Wood for more information on recommended products as well as instructions on application. 

  • What is your best product for gap-filling?

    Use our product Mirrorcast, a 2-part epoxy casting resin developed for just this purpose.  Watch the video, then click on the box below for complete and detailed descriptions and instructions.



  • Do Epoxy Coating Resins And Adhesives Shrink?

    Most epoxy systems will shrink in a range of 1-5% in volume once fully cured.  You will find that in most applications, this shrinkage is virtually undetectable. Where it can be noticed is when epoxy is used to fill voids such as large knots and cracks in wood slabs.  The best way to minimize the shrinkage is to slightly overfill these voids.  Additionally, allow the overfilled void to fully cure (4-6 days) before block sanding flush with the substrate.  

  • Coating Raw Wood with Epoxy

    System Three Coating Epoxies offer tremendous benefits in protecting and stabilizing wood components.  Not only do they offer exceptional protection from moisture, they also bring out a high degree of depth and beauty to wood. Coating epoxies can be used as the sole finish, or they can be implemented as a high-build protective sealer.  Most waterborne or solvent-based top coats can be applied over System Three Epoxies.  Exterior applications require a UV protective topcoat such as System Three Marine Spar Varnish or System Three WR-LPU.  Always test if not using a System Three topcoat.

    Stain can be used with System Three Coating Epoxies.  However extended dry time of the stain is necessary before coating can begin.  Traditional oil base stains work best, but need 5-7 days at room temperature to fully dry.  Waterborne and gel stains are not recommended.  As always, test your stain color with the epoxy before proceeding to your project. 

    Substrate Preparation:

    Wood must be clean and verifiably dry before coating can begin.  High moisture content can be problematic and should be avoided until moisture levels drop to 12% or less. 

    Sharp edges and outside corners are difficult to coat and more times than not, inadequate film build occurs, resulting in poor protection from moisture.  To prevent potential failure of the epoxy, edges and outside corners should be slightly rounded over.  You can round over or break the edge with sandpaper or using a router and a small radius round over bit.  Sand with 180-220 grit sandpaper.  Remove sanding dust from the wood substrate with clean shop air, or a vacuum.

     Measuring and Mixing:

    Most System Three Epoxies are mixed at an easy 2 Parts Resin to 1 Part Hardener.  Once epoxies are mixed, they have a limited pot life.  Because of this, it’s best to start with small 3 - 6 ounce batches to prevent loss of material. In a disposable graduated cup pour in 2 Parts Resin and then follow by adding 1 Part Hardener.  Mix with a flat stir stick, by scraping the sides, stirring from the bottom up.  Pour contents into paint tray or disposable pie tin.  Spreading out the epoxy prevents heat buildup and therefore increases your pot life.


    For interior applications, apply at least 2 coats of epoxy.  Exterior applications require 3 or more coats for good outdoor durability. 

    System Three Coating Epoxies are best applied with a 1/8” nap foam roller and disposable natural bristle brush.  Use the natural bristle brush to reach areas the roller cannot.  Optimal results are attained when the wood substrate is sealed with a very thin layer of System Three Epoxy at ½ fluid ounce per sq. ft.  Some porous woods may need an additional thin seal coat, applied at ½ fluid ounce per sq. ft.  Once the wood is sealed, additional coats can be applied.  Aim for 1-2 fluid ounces per sq. ft.  Vertical surfaces require thin coats to prevent runs or sags.

     Note:  Sanding between coats is generally not advised.  The sanding dust produced is very persistence and difficult to remove from porous grain.  If not completely removed, fine white specks will show on the next coat.  If sanding is necessary use 150-grit sandpaper.  Fine sanding dust can be removed with careful use of clean shop air or a good quality vacuum.  Wipe the surface with denatured alcohol. 

    Unlike other finishes, you can apply System Three Epoxy over itself, even when the prior coat is still tacky.  System Three Epoxies have a 72-hour window during which sanding is not necessary between coats.   

     Top Coats:

    When the epoxy has cured to a sandable state (24-36 hours) most topcoats can be applied.  Some spar varnishes are not compatible with epoxy.  Be sure to test ahead of time to determine compatibility.

    Sand the System Three Epoxy with the finest grit that efficiently levels the surface.  Best results are achieved by using a hard backed sanding block or electric sander with a dense rubber pad.  Care should be taken when using electric sanders, as too much of the epoxy surface can be removed.

    When sanding, be sure to maintain the proper grit sequence.  Failure to maintain grit sequence can end in scratches showing through the top coat.  Finishing with 320-grit sand paper is recommended for gloss finishes.  Satin finishes can be sanded up to 220-grit.

    Exterior application need at least three coats of a UV protective top coat for prolonged durability.  UV protective topcoats will periodically need recoating.  When the UV protective coating begins losing it luster, you should plan on recoating soon.








  • Best product for river rock tables.

    River tables are very popular in 2018.  System Three has developed a two-part epoxy casting resin called MirrorCast which is perfectly suited for pouring river rock tables.



    The product is brand new and has passed field tests with flying colors.  Complete product description and usage instructions are in the document below.

    acrobatpdf.jpg Mirrorcast™ Void and Crack Filler



  • Clear Coat vs. S-1 Sealer

    We carry two epoxy sealers, both of which will perform equally as a sealer. The differences are found in application and physical properties. 

    1) Clear Coat is a low-viscosity, 100% solids, solvent-free epoxy sealer that cures to a clear gloss finish. It has a 2:1 (resin:hardener) mix ratio by volume and is best applied by the roll and tip method.

    2) S-1 Sealer is a great alternative for a penetrating epoxy sealer. It is a 50% solids, solvent-based epoxy system that can be applied by brush, roller, or spray. This sealer has a 1:1 (resin:hardener) mix ratio by volume and offers a long pot life of 24 hours at 70°F. 

    The mode of application, porosity, and material of the substrate may be a good deciding factor in choosing the best sealer for your project. If the substrate is very porous, you might consider using the Clear Coat for its higher solids and faster film build. The S-1 Sealer may not be ideal for materials that are not compatible with strong solvents (e.g. EPS foam, thermoplastics). However, if you prefer to spray, S-1 Sealer is the product to use. 

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