Photo 1: This is a NOFMA Select Red Oak with an oil finish. Compare with Photo 2, a NOFMA Select White Oak. The red oak sapwood is slightly lighter but doesn’t contrast as much as the white oak.  The photo in real life also has a slightly reddish hue.

Photo 2: This is a NOFMA Select White Oak with an oil finish. Note the high contrast of sapwood white/cream with the brown heartwood.

Sometimes there appears to be a competition between the choices of “Red Oak” and “White Oak.”  Competition is really not the case as both classifications are equally suitable for a wood flooring application. As always, the customer expectation is the key as to which to choose. They do look somewhat different: however, the application of stains, particularly darker colors can almost moot this point. Red and white oaks are generally not just two different species of oak trees but they are two different groups of multiple oak species.

Photo 3: NOFMA No 1 Common Red Oak does have a quite variable color; however, not as much as Photo 4, the No 1 White Oak.

Red Oak group

The principle commercial species that make up the red oak group are: northern red, southern red, cherrybark, pin, scarlet, shumard, willow, water, laurel, nutthall, and black oaks. A primary character of red oaks is they do not have completely occluding “tyloses” in the open pores of the wood and are not a choice for tight cooperage. That is, they are not used for the famous southern whiskey barrels as the whisky would leak out during aging. The sapwood and heartwood differ in color generally in that sapwood is normally much lighter than the heartwood. The heartwood also generally has a red, pinkish or flesh tone to it. But color alone does not distinguish red oak as the overall color range is quite variable. The different species cannot be identified by their wood characteristics alone, microscopic analysis is necessary for these separations.

Photo 4: NOFMA No 1 Common White Oak; note the greater contrast than Photo 3; also, note there are more knots and color variation than the red oak.

The variability of red oaks is illustrated by their physical characteristics. For shrinkage values from green to oven dry the tangential shrinkage (plain sawn) can vary from 11.3% for southern red oak to 8.6% for northern red oak. Radial shrinkage (Quarter sawn) varies from 5% for willow oak to 4% for northern red.  The specific gravity at 12 % mc. can vary from .69 for willow oak to .59 for southern red oak. This is an important item in that non-invasive moisture meters rely on specific gravity to interpret moisture content. Side hardness is also variable from 1510 for pin oak to 1060 for southern red oak. The average red oak commercial shrinkage values from the USDA Wood Handbook: Wood as an Engineering Material, are 11% for tangential shrinkage and 4.7% for radial. For side hardness, 1290 for northern red oak is generally the published number.

Photo 5: This is a Select white oak floor with a light to medium brown stain. The sapwood portion did not absorb the stain. The repair for this floor is to individually sand and re-stain the lighter sapwood boards to blend with the rest of the floor. A good eye for color is necessary to pick the correct stain. After the staining the final finish coats can be applied.

White Oak group

The principle commercial species for white oak are: white oak, overcup, bur, chinkapin, swamp white, chestnut oak, post oak, and swamp chestnut. Live oak is also included but is not a species normally available for flooring. With white oaks the heartwood pores are occluded by “tyloses” so the whisky remains in the white oak barrels, except that chestnut oak may not have complete tyloses distribution and leak. The sapwood  of white oaks normally contrasts dramatically with the heartwood. White oak sapwood is typically a light cream color and heartwood is a rich medium brown to an almost greenish cast. In years past the grade of “sap clear,” composed of all sapwood without stain, would produce an almost ivory colored floor similar to a white maple.    

Photo 6: This shows an area of “tannin pull” in a white oak floor, the stained area in the center, from a water based finish puddle. This is peculiar to the oaks, with white oaks more prone to the condition. This is under the finish so sanding to bare wood is the method of repair.

White oaks also vary in physical characteristics. Their tangential shrinkage values range from 12.7% for overcup oak to 8.8% for white oak and radial values range from 6.6% for chestnut oak to 4.4% for white oak. Specific gravity varies from .72 for swamp white oak to .63 for overcup oak. Side hardness is from 1620 for swamp white oak to 1130 for chestnut oak. Average white oak commercial shrinkage values are 10.95 tangential and 5.4% radial. The published number for side hardness is 1360.

Comparing the two groups shows that in some ways they are quite similar and also different. The overall shrinkage characteristics for the plain sawn direction is almost the same where the radial is greater for white oak. White oaks are somewhat heavier and harder than red oaks. But the differences don’t end here.

Customer expectations are the most important part of choosing between red oak and white oak. The preference for color contrast and whether the reddish or brown tone is desired should be reviewed with the customer before the choice is made. One other item that can affect choice is the geographical area. In some areas only red oak or only white oak has been traditionally shipped. In others a mix has always been available. Put a red oak floor in a white oak dominated area and the consumer may object that it doesn’t look proper.  Memphis is a good example of species choice. Before the 1960s the preferred species was white oak. Since the 1990s the preferred species is red oak.

Mixed species planks in a site finished floor can be an issue raised by the consumer. Were customer expectations properly set? Most often in this case it is the color variation in question and the species is as it should be. But, what can happen is a bundle is mislabeled and that bundle’s planks all end up in the same area showing a different look. My advice is that if the plank/board looks dramatically different from the overall look of the floor you do not put it in. If the mislabeled bundle is installed any way, replacement of those pieces will normally be required.

Another issue that concerns white oak floors is the situation where the white sapwood does not accept stain. In this case white/cream sapwood remains white even after the rest of the floor is colored with stain. A simple re-sanding won’t fix the issue. Short of replacing the floor, mark those boards that show the condition and sand those boards bare. Selectively stain for a blending color, the choices may take several attempts to get the correct color. Then repair the surrounding finish by chasing the grain and coating the repairs followed by recoating the floor.

Finally, a condition unique to oak flooring is “tannin pull.” This most often occurs when a puddle of water based finish remains on the floor too long. The extractive tannins in the wood are placed into the water solution of the finish and create a stained appearance in the finish. Both groups can be subject to tannin discoloration. The effective repair is to sand the area to remove the discoloration and repair the finish.

Either red oak or white oak can be a good choice for flooring. They do have their differences and do perform somewhat differently but can all last the life of the structure with proper maintenance. Setting proper customer expectations will allow the consumer to make a choice they can be pleased with.