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and bright sells itself. Retailers, who market the added value of clean, mold inhibited pressure treated wood, can benefit from the increased sales and profib.

Jim Renfroe, manager, market development, for CSl, Charlotte, N.C., believes retailers can charge a premium for mold free products. "Because of the preference for clean wood. the retailer should be able to pass along any added cost when he promotes the greater appearance of mold free wood," he says.

PIESSURE treated southern yellow pine 0n the left had a chemical mold inhibitor applied as part 0f the treating process while that on the right did not. Photo courtesy of CSI n UALlTY-minded consumers

\f buying pressure treated wood products most likely will reject wood that has been blackened and stained by patches of mold in storage. For the retailer, blemished pressure treated lumber can prove costly. It can mean calls and returns, and profits reduced through waste or inventory mark-downs.

The remedy for a stack of pressure treated wood discolored by black mold patches used to be fairly labor intensive: get a scrub brush, a solution of bleach and water. and apply generous amounts of elbow grease.

However, today there is technology available to the treatment industry that can stop black mold before it gets established. Chemical mold inhibitors, and systems for delivering the chemicals during pressure treating, have been developed to prevent the growth of black mold in pressure treated wood inventories.

Without a mold inhibiting additive, the chemical preservatives used in pressure treating do not prevent the growth of mold and mildew spores, although they are highly effective against decay and insect attack. Unfortunately, microscopic, air-borne mold and mildew spores are everywhere. They thrive in the moist, dark atmosphere provided in a pack of freshly treated wood, commonly stacked while the wood is still wet from the pressure treating process.

Southern yellow pine, a predominant choice for pressure treated wood, and the humid climate of the southeast, can accelerate black mold growth. ln as few as two weeks following pressure treatment, visible mold and mildew growth can begin. Black mold may flourish in pressure treated wood held in inventory through the winter, since air cannot penetrate the bundle to dry out trapped moisture.

The problem often comes to light only when the pack is opened, revealing blemishes where moist growing conditions may have persisted for months. It is a problem only on the surface of pressure treated wood, and does not affect the structural properties or its long-term protection from rot decay or insect damage. However, since most pressure treated products are sold for decks, fencing and various d-i-y projects, cosmetic appearance is an important concern for the end-user.

A bad looking product, though perfectly sound, has a lower value in the eyes of the customer.

By comparison, wood that is clear

CSl, located in Charlotte, N.C., a supplier of chemicals to the wood industry, is one of the companies to include a mold inhibitor in its line. The product is called Moldex 1ltr14. According to Renfroe, the added cost for pressure treated wood with their mold inhibitor is about $l more per 1000 board feet.

"When you order pressure treated lumber that has been treated specifically with a mold inhibitor, you're buying in on a very powerful, highly efficient tech. nology," he says. For example, Moldex HE14 is added to the pressure treating work solution at a rate of 5 to 7.5 parts per million. The lower rate is for wood that will move through distribution quickly, typically in the summer; the higher dosage is recommended when inventory will be held longer. CSI's research indicates that mold protection should last for at least six months, or until the wood reaches a moisture content below 200/0.

Because Moldex HEt+ is extremely effective at low volumes, CSI also has engineered a system for metering the chemical into the pressure treating process. Their technology utilizes a closed system of injection, assuring that the correct amount of mold inhibitor is placed into the treatment solution every time, as well as assuring that pressure treatment operators are at minimal risk of chemical exposure.

Story at a Glance

As appearance is increasingly important in wood marketing, especially to the d-i-yer, mold inhibitors have become more important. . what they do, why it works and what it costs.

OOD preserving statistics for 1986 show the waterborne segment of the industry registered another outstanding year. By type of treatment, waterborne preservatives accounted for 375.5 million cu. ft. of the estimated total 1986 production of 554.1 million cu. ft. This was 14.50/o over 1985 and 67.80/o of the 1986 total volume.

These figures, the latest available, are based on reports for 518 plants and estimates for 70 non-reporting plants, according to George K. Eliades, president of the Society of American Wood Preservers. Inc.. Falls Church, Va.

Treatment of waterborne fire retardant chemicals increased in 1986 by 9.20/o over 1985 to 10.4 million cu. ft. Creosote solutions and pentachlorophenol volumes treated in 1986 were 118.7 million cu. ft. and 49.5 million cu. ft., respectively, decreases of 7.60/o and 5.80/o from 1985.

Lumber, timbers, cross ties, switch ties, bridge ties and poles accounted for 88.40lo of the total 1986 market. Lumber and timbers, 950/o waterborne preservative treated, accounted for 330.2 million cu. ft. (5,473.8 million b.f.) or 59.60lo of the 88.4010, while the tie market, practically all treated with creosote solutions, accounted for 86.4 million cu. ft. or 15.60/0. The pole market consumed 73.3 million cu. ft. in 1986; 57 .30/o treated with pentachlorophenol, 22.10/o creosote solutions, and 20.60/o waterborne preservatives, or 13.20/o of this category. The balance of production was 73.3 million cu. ft., largely posts, piling, plywood and miscellaneous treated products using all three preservative types.

Overall, total 1986 treated wood production was 6.7% above 1985. Southern pine accounted for 670/o of