Borogard ZB has been used in North America for years, with a broad spectrum of efficacy and low acute mammalian toxicity. However, WPCs treated with Borogard ZB are not suitable for ground contact and must be protected with a water-repellent coating when used in exterior applications (eg, joinery and siding).

Borogard ZB is leach resistant—only sparingly soluble in water at room temperature (< 0.28% w/w). It contains no organic components and does not require the use of organic solvents because it is applied as a dry powder.

By adding Borogard ZB before or during the blending process, you can achieve a thorough and uniform distribution of the chemical throughout the composite material. Efficient distribution of the preservative in the manufactured board can be confirmed by chemical assay.

Borogard ZB is chemically stable to 290°C and is not altered during normal wood composite manufacturing processes. Composites treated with appropriate levels of Borogard ZB generally retain their natural appearance and strength. Ferrous metals, plastics, rubber, putties, bituminous solutions, other sealants, primer, and finish paints are not adversely affected by wood composites treated with Borogard ZB.

WPC manufacturers should determine the Borogard ZB loadings for their treated products and end-use applications. Borogard ZB loadings should not exceed 8% (w/w), and loadings in excess of 1.5% (w/w) might require additional adhesive binder to compensate for possible effects on strength.