Compatibility of deltamethrin with wood-finishing and construction materials
E S Lepage
Under normal use conditions, treated wood comes to close contact with the structural components of a buiLding, and/or receives finishing, forming a new interface, which can affect the performance of a new product such as deltamethrin. To study this possibility, block-tests of Parana-Pine (Araucaria angustifolia), measuring 12 x 24 x 0.5 cm³ (with the largest dimension parallel to the wood-grain), received brushing treatment with deltamethrin and kerosene in two different concentrations: 0.02% (w/w) and 0.04% (w/w). After 20 days under laboratory conditions, the block-tests received a superficial finishing with poliurethan varnish, enamel paint, oil paint (alkidic) and latex paint and were fastened in close contact, through rubber band, with bricks, building cement, concrete blocks and plaster. A set of pieces made up of these construction materials was treated with deltamethrin in the same concentration as mentioned above, forming a reference series. The test against dry-wood termites (Cryptotermes brevis) was carried out 21 months after the treatment. The deltamethrin proved to be very effective in wood protection, independently of the finish used and the type of construction material in contact with the wood.