The Exudation of Oil Type Preservatives from Treated Wood

Thirty-five factors affecting exudation of oil-type preservatives from wood are listed and possible methods of control are discussed. The list of factors include nature and species of timber; machine trimming; mold and stain; degree of seasoning; time of, year; moisture content uniformity; initial steam use and length of initial steam period; length of vacuum period after steam; treating process; air pressure; preservative temperature; blow back; duration and intensity of final vacuum; final steaming; expansion bath; boiling under final vacuum; penetration and distribution of preservative in wood; amount of retention; retreatment; amount and nature of high boiling material in preservative; preservative viscosity; amount of insolubles, water emulsion, and sludge in preservative; intermixing of preservatives in treating plant; antiblooming agents; effect of light, storage time, variation in temperature of wood, and accumulation of extraneous materials on wood; and area where shipped. Some of the suggested means of controlling oil-type preservative exudation include machine trimming of round pieces, control of staining and molding, separation of wood to be treated into as uniform batches as possible, adequate vacuum system, use of maximum possible preservative temperature (200 to 210?F at end of creosote pressure period), minimization of air in blow back, overinjection of preservative when extreme cleaning is planned, keeping preservative and tanks clean, prevention of preservative admixture, maintenance of water content below 2 percent and distillation residue below 30 percent (creosote), and use of antiblooming agents as necessary.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member