Hardwax Oils have increased in popularity over the last ten or so years and it’s easy to see why: a simple wipe-on/wipe-off finish that leaves a nice consistent surface is pretty much every woodworker’s dream. For the longest time, Rubio Monocoat was the only game in town (at least in the category of 2-component hardwax oils) and their high pricing seemed to reflect that. Fast-forward to 2023 and suddenly Rubio has serious competition, with several new 2-component offerings from other companies. Suffice it to say that the game has changed, and I’ll be very interested to see how things shake out over the coming years.
In the meantime, I decided to put these finishes to the test. I tested cherry and walnut samples all cut from the same board. Finishes include:
Test samples were observed for overall sheen after both one coat and two coats. Because it’s very difficult to capture subtle difference in sheen in the form of video, we instead decided to do some blind testing instead, with three separate people.
The sheen test was quite definitive even though the differences detected were subtle. With one exception (Nicole wasn’t able to pick a ‘least sheen’ for cherry) we all selected Osmo for the most sheen and General Finishes for the least sheen on both the cherry and walnut samples. The other three finishes (Rustic Lumber, Natura, and Rubio) were indiscernible. Note that Osmo was the only finish in the test that had a decent amount of gloss after just one coat. All others showed a significant improvement in sheen after a second coat but still couldn’t match Osmo.
I tried several different ways to test abrasion on my sample boards in a meaningful way. Unfortunately, given that these finishes are not film-forming and don’t offer much protection beyond resisting liquids, I couldn’t come up with a test that produces actionable results. Abrasion durability, in the case of most hardwax oils, is more about the natural durability of the wood and not so much the finish. In my opinion, comparing these finishes based on scratch resistance is a little like debating which brand of plastic wrap makes for the most suit of armor.
Each sample was divided up into six sections and each section was exposed to a different liquid/wet material. The samples were exposed for 15 minutes. Because of the damage observed at 15 minutes, I felt no need to do an extended overnight exposure test. If you’re interested in seeing how each sample fared, please check out my spreadsheet. Hardwax Oil Comparison – Liquid Test Spreadsheet
Results (higher number means MORE damage):
There’s nothing worse than spending a lot of money on a finish, using it once, and then coming back a month later to a can of solidified material. So I tested the oil components alone (no hardener) to see how they behave when exposed to oxygen for 24 hours and then 48 hours. I’m theorizing that the oils that set up the fastest will also be the oils that are most likely to set up prematurely in the can.
General Finishes was still in a liquid state with no skin after 48 hours. Natura Onecoat was still liquid after 24 hours but skinned over by 48 hours. All other finishes skinned over after 24 hours.
One of the main selling points of hardwax oils is their repairability. Traditional film finishes are difficult to repair since you have to sand several layers of finish before getting to the wood. Applying finish on top just makes matters worse as the layers become more visible and the new film becomes impossible to feather into the surrounding area. Due to the nature of hardwax oils and their non-film-forming characteristics, we should be able to do clean spot repairs. To test this, we took our sample boards (which now contained damage from the liquid tests) and subjected them to a repair. The board was sanded to remove raised grain and dulled finish. We tried to focus on the damaged areas with only a very light scuffing in the surrounding areas. The surfaces were then cleaned and recoated with their respective finish.
Every sample board had a very obvious repair. From some vantage points, the repair can’t be seen but from MOST vantage points, it can. While I’d say these finishes are still far more repairable than something like a traditional varnish or poly, I can’t say that the repair is perfect, or even great. In fact, if this was a repair on a table for a client, this repair would not pass muster. When I do repairs with these finishes, I usually count on sanding back the entire surface that’s getting the repair and then recoating that entire surface all at once. Here’s the Tanin Remover I mentioned: Rubio Tanin Remover
First things first. It’s important to realize that these finishes are more the same than they are different. This class of finishes has a fixed set of properties and the differences between them are minute.