re: Lets Talk "oil finishes"

If it’ll go on wood, I use it.

I always have a couple gallons of hardening oils on hand – one of boiled linseed oil and one of tung oil. They sit next to my gallons and quarts of waterborne and oil based ply finishes. The latter include some from Daly’s (scored them for a dollar a quart from a place going out of business), Varithane and so on. They include satins, semigloss and clear. They also include interior and exterior finishes.

I don’t have a lot of love for most clear coats on exterior wood. While the high end stuff (e.g., $150/gallon) will hold up to marine environments, it remains there is no magic, maintenance free product.

Since I and my customers are too cheap to use the high end stuff, I make my own long oil finishes by merely adding tung oil to poly.

When playing with items that were (and did) sit in front of a fire place for decades, I thinned the product about seventy percent using paint thinner and applied it as long as it would soak it up, then just added more throughout the day, when I walked by or thought of it. When the day was done, a six inch slab was, literally, saturated through. After that, I backed off on the thinner, first to fifty percent, then about fifteen. Forty years later and no cracks.

My rule in life and dealing with wood is simple:

Wood shrinks as it dries out. Accordingly, do everything you can to diminish shrinking and, of course, expansion by way of moisture transfer.

Oils don’t evaporate. Still, applications seem to disappear. This is because the oil wicks cell to cell. One of the best example of this I saw was a garage door I built using northwest red cedar salvaged from a spalt pile at a friend’s cedar mill in the Pacific Northwet. The first coat of used motor oil I applied lasted about three months. The second, only a little longer. The third, on the other hand, is still notable a decade later.

I applied what I learned from the above situation to a butcher block I purchased on the cheap. The joints were separating and the wood was cracking and splitting from shrinkage.

I flowed mineral oil on and kept doing it until is quit sucking it up. Then I slathered on one last, very generous coat and walked away. A few weeks later, I looked at it and all the cracks, splits and separations were gone. The wood had swelled back until the oil saturated it similar to what its original moisture content was.

In short, applications of non-hardening oils are cumulative. The wood needs time to absorb oil, but an aggressive oil regimen

Obviously, a hardening oil would not work, since it would harden before it could swell the wood back to its original dimensions.

These concepts should be considered for furniture too. I have even read pro’s (the names of whom most here would recognize) ramble garbage about not finishing the inside of chests of drawers and things, even as they, elsewhere, warn of the problems of moving a piece of fine furniture from England [or the Pacific Northwet] to Arizona, because of the moisture loss and subsequent wood shifts that damage the piece. In short, religious oiling CAN replace lost moisture and has been proven to work.