temperature should initially be equal to ambient temperature i e 10 u00b0 30 u00b0 c and the product temperature should initially i e just prior to wetting be between 30 u00b0 c and 60 u00b0 c preferably the product should be at a temperature of about 40 u00b0 c i e the temperature reached as the product travels at ambient temperature from the furnace outlet to be wetted the wetting or spraying is performed continuously during malaxing by a high spraying ramp placed along the malaxer until saturation during the advance to the malaxer the speed of rotation of the screw is adjusted so that the product advances in the malaxer at a speed of about 3 m min it is estimated that saturation is reached at the end of 2 to 5 minutes the first impregnation performed hot completely expands the wood pores previously opened by mechanical treatment and cleared by heat treatment the complete opening of the pores enables later treatment described hereinafter to be performed perfectly to the very heart of the wood as soon as the wood enters the second linear part of the malaxer a solution of an alkali metal silicate of the same concentration as the calcium salt solution is then made to act by spraying at ambient temperature from an upper ramp in an amount between 2 and 15 by volume of the wood but preferably.