Oak is one of the most common furniture woods in older pieces. It is hard, durable and takes stain well. It also has a few quirks: open pores that trap residue, a tendency to form iron stains, and a grain that shows every bit of dirt left in it. These tips cover the main points.
Red oak and white oak: how to tell them apart
Red oak and white oak look similar but behave differently.
- Red oak has a pinkish cast and short rays. Its pores are open.
- White oak is more olive or tan, with longer rays. Its pores are plugged with tyloses, a structure that makes white oak more water-resistant.
Red oak has a Janka hardness of about 1,290 lbf, and white oak about 1,360 lbf. The difference is small, but because red oak’s pores are open, water and stain can behave differently on the two. Test on a hidden spot before you commit.
Quartersawn oak and ray fleck
Quartersawn oak shows ray fleck, a flake-like pattern that comes from the wood’s rays. It is typical of Arts and Crafts and Mission-style furniture. If a piece looks like an antique, check its value with the old furniture value guide before you make major changes.
Clean out open pores before finishing
Oak’s open pores trap stain, wax and stripper residue. Before you stain or finish, scrub the pores with a brass or nylon brush and a suitable solvent. Residue left in the pores shows through the new finish as dark streaks or cloudy spots.
If you want a glass-smooth surface, use a grain filler. Without it, the pore texture stays visible, which many people like. Choose based on the look you want.
Black stains from iron and tannin
Oak contains tannin. When tannin meets iron, it forms blue-black stains. Iron can come from steel wool, nails, screws or water with a high iron content, and water can bring out the stain.
To treat a black stain, use oxalic acid, then rinse according to the label. Black stains usually go deep into the wood, so sanding alone rarely removes them. Avoid steel wool on oak before a water-based finish. A synthetic pad is safer, because leftover steel fibers can rust and stain the wood.
Oxalic acid is toxic. Wear gloves and a mask, and don’t breathe in dried crystals.
Sanding and grain filler
Sand oak to 150 to 180 grit before you stain. Going much finer can make the surface less absorbent, so the stain may look lighter and patchier. Sand with the grain, and hand-sand at your final grit to remove swirl marks. What grit sandpaper to use on wood furniture explains the progression.
Stain, conditioner and liming wax
Oak rarely blotches, so many refinishers skip pre-stain conditioner on it. Some do use one. Test on a hidden area and use a conditioner only if the test shows uneven absorption.
For a light, aged look, liming or cerusing wax works especially well on oak. The white wax settles into the open pores and emphasizes the grain. Seal it with a topcoat as the product directs. The same idea is behind pickled oak kitchen cabinets.
Golden oak and fumed finishes
Many oak pieces from roughly the 1900s to the 1920s were finished with an orange shellac over stained oak, a look often called golden oak. Mission-style pieces were often darkened by ammonia fuming. Fuming gives a shallow color that sands off, so a fumed piece can look quite different once it is sanded.
Don’t try fuming at home without the right equipment and training. Strong ammonia fumes are a serious hazard to the eyes and lungs.
Safety
- Oxalic acid is toxic. Wear gloves and a mask, and rinse thoroughly as the label directs.
- Strong ammonia fumes can damage your eyes and lungs. Work with good ventilation.
- Sanding oak produces fine dust. Use a respirator rated for wood dust and dust extraction where you can.