Doesn’t that Interfere With Finishing?

The answer is “no.”

What’s the question? “Doesn’t (oil, tallow, paraffin, beeswax, snake squeezins, earwax, monkey fat) interfere with finishing?”

Still, the answer is “no” – unless you are using some wacky exotic ingredient, or you are rubbing it on like butter.

I know that it’s almost impossible to prove a negative, so permit me to make the following statement: The only workshop liquid or lubricant that has even given me problems with finishing has been glue that I failed to wipe up. I have rubbed my tools with almost every known lubricant on the market, the balm of forbidden trees, oils from the crevices of my body (not kidding), solid waxes. None has ever interfered with finish penetration or adhesion.

So why don’t common workshop lubricants cause trouble? Many of them, such as paraffin, are made from mineral spirits or are easily displaced by mineral spirits. So when a finish, stain or dye with mineral spirits encounters your lubricant, nothing bad happens.

And what if you do use a “bad” lubricant that didn’t mix with your finish? Usually the way you use them prevents them from messing with your finishes. You rub the lubricant on the tool. That’s a thin film. You then rub the tool on the wood. Most of the lubricant ends up on the shavings or in the sawdust. Every time you stroke the tool, the film gets thinner and the amount transferred to the wood get smaller, and almost all of it is cut away by the tool itself.

Wax on the infeed bed of the powered planer is cut away. Lubricant on the plane sole is cut away by the stroke you are making and the next stroke. Tallow on the saw ends up in the sawdust or on a surface that doesn’t get finished (the end grain of a joint surface, for example).

This evening I had some fun with lubricants. I rubbed paraffin, mutton tallow and jojoba oil directly onto some cherry and walnut. I rubbed the lubricant into the grain with great friction. Then I tried finishing it with boiled linseed oil and then varnish. Both were cut with mineral spirits. I could not see any finish penetration problems. They dried just fine.

Varnish and oil on the board

Then I rubbed the same lubricants on the walnut and cherry and added a dye and pigment stain to the wood. Both blotched (naturally), but I couldn’t see any problems where the lubricants were preventing the dye from coloring the wood.

Pigment and dye on the board

I know this doesn’t prove anything to anybody but myself. But perhaps someone out there will stop worrying as much about finish penetration and worry more about what can affect finishing – how consistently and carefully you prepare every surface of your project, whether it’s with sandpaper, a scraper or a handplane.

Because it’s not the lubricants that interfere with finishing, it’s usually the finisher….

— Christopher Schwarz

Become a Better Finisher – the Flexner Way
Check out Bob Flexner’s “Understanding Wood Finishing, Revised Edition,” the single best book on the topic. Also, “Flexner on Finishing” has a lot of good finishing information in it. And if you are a beginner, then definitely check out “Finishing 101” – the best basic finishing book I’ve encountered (it’s also by Flexner.)