Epoxy, O what a versatile glue...

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Review by DoctorDan posted 02-06-2011 07:59 AM 6533 views 1 time favorited 5 comments Add to Favorites Watch
Epoxy, O what a versatile glue... No-picture-s No-picture-s Click the pictures to enlarge them

What is Epoxy?
The all knowing all seeing Wikipedia ’Epoxy is a copolymer; that is, it is formed from two different chemicals. These are referred to as the “resin” and the “hardener”.

The resin consists of monomers or short chain polymers with an epoxide group at either end. Most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A, though the latter may be replaced by similar chemicals. The hardener consists of polyamine monomers, for example Triethylenetetramine (TETA).

When these compounds are mixed together, the amine groups react with the epoxide groups to form a covalent bond. Each NH group can react with an epoxide group, so that the resulting polymer is heavily crosslinked, and is thus rigid and strong’.

Which Epoxy do I use?
In woodworking Epoxy is the choice of glue when gap filling is required. The most common wood glues are PVA like glues that require zero-clearance. These glues are not self supporting and any gap will lead to a tremendous reduction in bond strength. Epoxy left alone become a plastic like rigid structure can bridge gaps. Woodworking applications include to bond poorly fitting joints, filling defects in wood (checks, bore holes, splits), and useful on endgrain as it doesn’t absorb along the fibres as other glues.

At present, West System Epoxy is my epoxy of choice. It is available from woodstores like Carbatec and boating and fiberglass stores. The cheapest supplier I’ve found is Fibreglass Material Services in Broadmeadow. Bought from these suppliers it is often cheaper than more main stream handy man brands like Shelly’s.

West System Epoxy is a very low viscosity product (very thin and watery). They sell a variety of filler like silica/microfibre powders that can be added allowing you to increase the viscosity to whatever the application demands. I have not seen this level of versatility in other epoxy brands.

Application 1: Fixing the Dust Extractor
A recent Dust Extractor mishap left the impeller housing split. After some encouragement (with a hammer) the housing went back together. To seal the joint and fill any gap I used epoxy mixed with iron oxide to thicken the glue. This will be then be sanded smooth and the paint job refreshed.

Application 2: Filling Wood Defects
Wood is not a homogeneous man-made product, but an organic (ex-)living tissue. Defects form by grow patterns (such as burls and branch points), insect attack (borer holes), and issues with drying (checking). For a consistent and stable finish these defects need to be filled. Here I am using West System epoxy with the silica/microfiber filler to fill gaps and stablise a burl. The excess can be scraped back and then sanded level with the wood.

This filler produces a clear/slightly white finish. Often it is more aesthetic to actually use a black filler. In the past I have used shoe polish and ebony sand dust. Iron oxide used to colour concrete is a cheaper and easier alternative. With shoe polish I noticed that the colour bled into the wood. To counter this you can use a shellac sealer to seal the wood prior to applying the epoxy.

Epoxy, O what a versatile glue…

-- Daniel -

View DoctorDan's profile


281 posts in 3863 days

5 comments so far

View Pete_Jud's profile


424 posts in 4600 days

#1 posted 02-06-2011 08:39 AM

I have used West System epoxy on my boats for years. You can put over poly resin, but it needs UV protection if used out doors.

-- Life is to short to own an ugly boat.

View tenontim's profile


2131 posts in 4592 days

#2 posted 02-06-2011 03:20 PM

Epoxy is great stuff. I also use it for making “knots” (with the appropriate coloring. I get a squirt of the epoxy coloring from the local paint store.) I occasionally get request for inscriptions in a piece and will fill it with a colored epoxy, to give it an inlay look.

View cornflake's profile


36 posts in 3538 days

#3 posted 02-06-2011 04:50 PM

i have made designs in segmented turnings with epoxy mixed with lacquer based dyes it works real good

View MontanaBob's profile


873 posts in 3531 days

#4 posted 02-07-2011 06:02 AM

I’ve used Brownells Acraglas for years to make many types of wood repair….It comes with brown & balck dye, and a releaseing agent just in case you are inletting a gun barrel. Probably need to pick it up from a firearms dealer or sport goods shop…. The box of Acraglas that I have now has been around here for seven or eight years and it still works…. The dye is long gone…... I don’t know if it’s needed but I drill small holes in both pieces and fill with Acraglas to get a good bond….

View childress's profile


841 posts in 4389 days

#5 posted 02-08-2011 12:16 AM

I just bought some last week. Spent about 80 bucks for 105 resin, 205 hardener and the dispensing pumps. Seemed like a lot, but after my first use, it’s worth the $$. Beats any other epoxy I’ve tried. Great stuff and good review. Thanks

-- Childress Woodworks

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