Wood Filler & Epoxy Test (Year 5)

By Scott Sidler • September 23, 2019

wood filler testYear five is finally here and I will be showing you the results of my testing of five of the most popular wood filler and epoxy products on the market today. This will be the final year since after five years the chunk of cypress wood I used has suffered so much rot that the wood fillers are all that’s left! These wood fillers and epoxies have been exposed to the harsh Florida weather to help you find the best wood fillers on the shelf today this test has been a very telling study of how they each perform.

In this last year you should have a good sense of what products you can use effectively and which you should stay away from. The five products I tested here are Abatron WoodEpoxMH Ready PatchJB Weld KwikWoodMinwax Wood FillerMinwax High Performance Wood Filler. I chose these 5 because they represent a wide variety of formulations. WoodEpox is a structural wood epoxy for both large and small patches, Ready Patch a spackle for wood uses, KwikWood a simple two-part fast cure patching epoxy for small areas, Minwax Wood Filler is your standard multi purpose water based wood filler, and the Minwax High Performance Wood Filler is a styrene/resin filler similar to Bondo.

The Test Conditions

To make this test as scientific as possible, I’ve outlined the rules and conditions below.

I drilled out a 1/2″ deep hole with rough edges to try to simulate a chipped or gouged board and filled the hole above the surface with filler, after which, the patches were sanded level. Here are the conditions:

  • The wood fillers and epoxies were all mixed and applied according to the manufacturer’s specifications.
  • The wood use was a piece of 1 1/2″ thick rough sawn cypress.
  • The sample was laid horizontally outside.
  • The wood and fillers/epoxies received no pre-treatment, primer or paint other than WoodEpox which was used as per the manufacturer’s instructions with LiquidWood prior to application.

All the fillers and epoxies were applied and left to cure/dry until they were ready to sand smooth. I ranked the fillers in my previous post regarding ease of application, ease of sanding, and drying time.

The sample board was left outside uncovered laying horizontally. I will qualify this by saying that all of these manufacturer’s recommend that their products be primed and painted even though I have left all of them without any primer or paint.

This test will clearly show different results than if I had painted the repairs, but I decided that seeing how a product would stand up to unprotected exposure and on a horizontal surface would show results more quickly and accurately as to which product has the greatest staying power.


Product Info: 2-part epoxy filler

Test Results: After the first couple years the WoodEpox settled in and really hasn’t changed much at all. The same hairline cracks exist with no structural issues. It is still solidly attached and will not budge from the hole. A strong performer in my book especially since this can work for both structural reconstruction of pieces and easy wood filling like this.

ready patchReady Patch

Product Info: Spackling Compound

Test Results: It hung on till the end, but just by the skin of its chinny-chin-chin. The first year it suffered the most serious shrinkage of all the fillers and that was even in the first month. This year the cracking and separation around the edges got so severe that when I check the stability of the patch I could easily pry it out with a finger nail. Maybe I’d use this for a nail hole for gouges or anything larger this is clearly not a good choice.


Product Info: 2-part epoxy filler

Test Results: Still a solid patch that won’t budge under my extremely scientific “finger-nail prybar” the KwikWood has proved a solid performer over these last five years. I was especially impressed with the lack of mildew or algae growth on the patch. A great easy to use patch that will definitely stand the test of time. The only downfall is that it comes in small quantities so making larger patches is not feasible.

minwax wood fillerMinwax Wood Filler

Product Info: Water-based wood filler

Test Results: This was the total surprise and dark horse. I never thought this would last more than a couple years, but it has stayed strong just like the expensive epoxies. Of course, this is not a structural filler and I wouldn’t dream of rebuilding structural members or using it where holding power for screws or other fasteners is critical, but for filling small to medium size holes affordably this is now my go to product.

minwax hp fillerMinwax High Performance Wood Filler

Product Info: 2-part styrene/resin filler

Test Results: This Bondo style wood filler performed admirably and passed the finger nail test even with some real effort behind it. It did develop some of the most significant perimeter cracks of all the filler besides the Ready Patch which leads me to believe that over the long haul it will have a shorter lifespan due to water getting behind the patch, but for 5 years it is still solidly intact. It would likely not look as attractive under paint due to the cracking, but so far so good.

Final Thoughts

This has been a fun test for me to see these products perform in real life and in my climate. The result you get may be different from what I have found since no one’s climate is exactly the same, but the general results are very applicable I think. I encourage you to do some of your own testing in your area on anything you want to know the long term performance of.

Don’t blindly trust the manufacturers, do your own due diligence whether it’s paint, wood filler, wood species, glazing putty or whatever matters most to you. If you have some test results from your own projects feel free to share them in the comments below so we can all learn and DIY better!

If you have found this test helpful consider purchasing any of these wood fillers by clicking any of the links on their names through my Amazon affiliate links to help support the blog. It costs you nothing, Amazon just gives me a little commission for sending you their way.

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7 thoughts on “Wood Filler & Epoxy Test (Year 5)”

  1. Hi Scott!
    Amazing test and thanks for sharing. I have had a box of wood epox in the basement that was previously used and I believe it maybe 10 years old. I was desperate to get going on some small repairs and tried mixing a small amount up the night before to see if it would still harden as it said it has a shelf life of I believe one year. It hardened very well so I went ahead with it based on not wanting to throw an expensive product in the garbage. I used it and am now getting ready to prime and paint but I guess time will tell if it holds up over the years, if not then I will just go at it with fresh wood repair and is easy since it is ground level repair work on our porch.
    Thanks again for great info!

  2. Thank you so much for the 5 year update. This update came just at the right time. My house is 90 years old & I need to make some repairs. I always look forward to you newsletter & blog.

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