Our Exterior Oil Finish
The surface quality of wood furniture is difficult to maintain outdoors. The cycles of humidity and temperature cause the wood to shrink and swell, opening the pores and raising the grain allowing deposits of dirt and mildew to accumulate. The design of our outdoor furniture accommodates the structural stresses wrought by the shrinking and swelling, and mahogany is a rot resistant wood that holds up well to these stresses. The oil finish provides protection, for a limited time, of the surface and makes maintenance and refinishing relatively easy.
We apply three coats of an exterior rated oil finish in the same way as we apply our indoor finish (but we do not add varnish). Click to see How We Apply Hand-rubbed Oil. The exterior oil has compounds added that resist degradation by ultra violet radiation and the growth of mildew.
Changes Over Time to Our Outdoor Furniture
Over time, ultra violet radiation degrades all finishes and bleaches the natural colors of wood to some shade of gray. You can expect this transition: Our oil finished, mahogany furniture will be quite light when you get it. It will darken into a rich, red brown over the first year or so. This is the color most of us wish was permanent. But out on the porch, over three to five years, the wood will begin to become grayish and ultimately will become completely gray. You can maintain a silver-gray, a rather nice color, by occasional washing as below. You can return the chair to red-brown by sanding and re-oiling, also described below. You probably won't need to do anything for the first couple of years beyond wiping it down with a wet rag or sponge. Your personal sensitivity to this graying should guide your schedule of maintenance.
We developed the maintenance steps below by keeping a rocking chair on the porch for 10 years and studying the effects of time on it. We did no maintenance other than an occasional scrubbing with a soapy rag and a rinsing with a wet one. That chair is structurally sound, but was dark gray and had a few shallow checks in the wood when we gave it a thorough reconditioning.
A Flexible Schedule for Maintaining Our Outdoor Oil Finish
- When you decide it needs it, scrub the furniture. Use Murphy's Oil Soap or something similar. We use a bucket with about a half gallon of soapy water and a dishwashing sponge with a scrubber surface. Rinse with clean water in the bucket using a cloth or sponge. Dry with a towel.
- A semi-annual scrubbing will lighten the chair and clean it, making it more pleasant to view and to use.
- After a few scrubbings, the chair will be light gray and the wood will seem dry.
- When the dry look bothers you, it is time to sand and oil. Allow 3–4 days drying time after scrubbing. Sand the chair with 220 grit sandpaper. Don't worry too much about sanding with the grain at every point, just make the chair smoother.
- Most hardware stores carry an outdoor oil finish. If you have a question about a product, please ask us. We use Penofin Penetrating Oil Finish.
- Set up outside where you can make a mess. Wear old clothes and rubber gloves. Put some finish in a bucket.
- Carry plenty of finish to the chair with a wash cloth sized rag. Flood it on and rub it in. Keep going over the chair and adding oil to satisfy the porosity of the wood. After 20–30 minutes or as you feel the material getting sticky, wipe off ALL excess with clean rags.
- Let the chair set for an hour and wipe it down again. Take special care to dry the excess at the joints and intersections.
- To lengthen the time that the finish will last, re-oil the chair after 2 days (steps 6 and 7). This should be a much lighter application.
- OILY RAGS CAN SPONTANEOUSLY COMBUST. Let them dry on a line or limb until crusty before disposal. NEVER make a pile of them.