Species and Finish in Conditioned Rooms

A cooling-unit manufacturer, Breezaire, publishes the target: desired cellar conditions are generally around 55 degrees Fahrenheit and 50 to 75 percent relative humidity. The Forest Products Laboratory’s Table 4–2 converts that into what wood will do. At the 50-degree row, equilibrium moisture content runs 9.5 percent at 50 percent humidity, 10.3 at 55, 11.2 at 60, 12.3 at 65, 13.4 at 70 and 14.8 at 75. The 60-degree row is within a few tenths of a point of each of those.

The handbook’s Table 13–2 gives the comparison. For interior woodwork, flooring, furniture and trim it recommends an average moisture content at installation of 8 percent in most of the United States, with individual pieces between 6 and 10; 6 percent in the dry Southwest; and 11 percent, with pieces between 8 and 13, in damp, warm coastal areas. A wine room at the middle of its band holds wood at roughly 12 percent — above even the coastal figure, and half again the moisture content of the kitchen cabinets on the other side of the wall.

The handbook also notes that hardwood lumber for furniture, cabinets and millwork is usually dried to 6 to 8 percent. Stock at that moisture content will swell in a wine room until it reaches equilibrium with the air, and its instruction is unambiguous: install wood at the moisture content it will experience in service. For a cellar that means the material is conditioned toward the room’s set point before it is machined, and the room is at its set point before the millwork is fixed.

Table 14–1 groups domestic and imported woods by average heartwood decay resistance. In the resistant group it lists the cedars including western redcedar, old-growth redwood, the white oaks, black walnut, and American mahogany. Young-growth redwood is placed in the moderately resistant group. Red oak does not appear in the resistant group, and the handbook’s footnote warns that decay resistance may be less in warm, humid conditions and that substantial variability is encountered within most species.

The handbook’s species notes agree with the table. Of western redcedar it says the heartwood is very resistant to decay and the wood has very low shrinkage. Of redwood, that typical old-growth stock is easy to work, generally straight-grained, and shrinks and swells comparatively little. Of American mahogany, that it is rated durable in resistance to decay fungi, has excellent dimensional stability, is very easy to work, and is easy to finish and takes an excellent polish.

Two cautions attach to the table. The first is that it describes heartwood: the handbook notes that marketable sizes of some species are primarily second growth with a high percentage of sapwood, and that where decay resistance matters it is important to utilize heartwood. Racking stock is specified as heartwood, and it is checked for it. The second is that a wine room should never be wet enough for decay to be the governing risk — the cooling-unit manufacturer’s guide warns that at 100 percent relative humidity mould and mildew form on bottles and walls. Decay resistance is a margin of safety, not a licence to run the room wet.

The racking field is the bulk of the room and the least seen. It is cut from a calm, decay-resistant heartwood — old-growth redwood where it is available, otherwise redwood or western redcedar selected for heartwood — in solid, at the widths racking needs, because the coefficients allow it. It is usually left unfinished. Cedar’s scent is a consideration some collectors raise; where it is, redwood is the answer. The companion article on bottle count and rack geometry sets the sizes.

The display millwork is what the room is seen to be: the label-forward rows, the large-format cubbies, the panelled wall behind the glass. Mahogany is the traditional choice and walnut the richer one; both are in the resistant group and both have coefficients close enough to redwood that solid members at display widths are reasonable. Wide panels go to a veneered construction over a stable core whatever the species, so the face is mahogany or walnut and the arithmetic is the core’s. These pieces are finished — colour, sheen and protection — in the workshop and cured completely before delivery.

The counter and the structure are white oak when they are oak at all, quartersawn so that the 0.00180 radial coefficient governs rather than the 0.00365 tangential one, and finished as display millwork. Red oak, the common kitchen species, is left on the other side of the wall: it does not appear in the handbook’s resistant group and it is the most active tangentially of everything on this page. The kitchen outside the envelope can be red oak, painted maple or anything the owner likes; the room inside it is chosen from the shorter list.