If you don't want to coat your wood paneling, cabinets or woodwork with a film finish such as varnish or lacquer, you might consider protecting it with a penetrating oil, such as tung oil or linseed oil. Teak oil isn't a true finishing oil, nor is it a film finish -- it's actually a wiping varnish, which is a little bit of both. Checking the label of a teak oil product won't give you many clues about how to make it, because not all the ingredients are usually listed. One thing you can be sure of, though, is that teak oil doesn't come from teak.
Characteristics of Teak Oil
To understand teak oil, it helps to know the characteristics of true finishing oils, of which boiled linseed oil and tung oil are the only two common examples. Both of these oils polymerize in contact with air and turn hard, but they tend to be viscous and may not settle deeply into close-grained wood. Teak oil -- which was formulated for teak, which is already oily -- is a blend of oils and solvents that provides deeper penetration and less surface visibility. There is no single formula -- some teak oils even include fortifying amounts of alkyd or polyurethane resins, which add luster and extra moisture protection.
DIY Teak Oil
If you're going to make teak oil, it's natural to expect oil to be the main ingredient, but there's no consensus on which one to use. One formulation relies on linseed oil, while another uses dehydrated castor oil, and still another lists no oils in its material sheet; finishing oils aren't considered hazardous materials and don't have to be disclosed.
Start With Oil
The decision regarding which oil to use as a basis for your homemade teak oil is open, but it's best to limit it to a finishing oil that will harden in the grain and protect it. This narrows the choice to two possibilities: tung oil and boiled linseed oil. Both are readily available at hardware and paint stores.
Add a Solvent
Because teak oil is a thinned-down version of a finishing oil, you'll have to add a solvent. Petroleum distillate, also known as mineral spirits or paint thinner, is a likely choice; many varieties of teak oil contain it. You might also choose naphtha, another petroleum product with a faster evaporation rate, if you want a faster-drying oil.
Plus a Pinch of Varnish
Resin is optional in teak oil, but adding some can make the oil more protective and lustrous. To fortify your mixture with resin, simply pour in a small amount of alkyd or polyurethane varnish. Be sure the solvents in the varnish are compatible with those you're using in the oil.
Mix It All Up
Measure a quantity of finishing oil and pour it into a container.
Add the same amount of compatible thinner to reduce the oil by 50 percent.
Test the oil by wiping some on a board of the same material that you want to finish. It should penetrate deeply enough to leave the surface slightly discolored and with a subtle oily feeling. Add more oil or solvent as needed to refine the surface texture to your liking.
Pour in a small amount of varnish -- 10 percent of the total mixture or less -- to give the oil more body. Wipe more on a test surface and refine the proportions as needed.