GB427154A - Process of colouring wood - Google Patents

Abstract

427,154. Colouring wood. SINGER MANUFACTURING CO., Elizabeth, New Jersey, U.S.A. July 11, 1934, No. 20317. Convention date, Sept. 8, 1933. [Class 140] Wood is coloured by treatment with gaseous ammonia in a closed receptacle in which a forced circulation is set up. The wood which need not be dried is piled on a truck which is placed in a cylindrical vessel 1 closed at each end by doors 2, secured by hinged bolts 3 and nuts 8. When released the doors are supported by cables 11 attached to an overhead trolley by which they may be swung away from the ends of the cylinder. The vessel 1 is heated by steam pipes 20 fed from inlet pipes 23, 24 and headers 21 and exhausted by outlets 25, 26. A perforated pipe 28 may be used to inject steam directly into the vessel. The forced circulation is induced by fans 30, 31, 32, 33 disposed in staggered relation at opposite sides of the vessel. Gaseous ammonia may be supplied by evaporating aqueous ammonia injected into the vessel or in an external evaporator or from anhydrous ammonia containers. After introduction of the wood the fans are started, steam is admitted to the radiators to raise the temperature to above 212‹ F. and below 350‹ F. and the vessel is partially evacuated to remove air and moisture, after which the ammonia is introduced. Drying of the wood during colouring is controlled by relief valves which may be set so that the operation may proceed at a pressure below or above that normally developed by the ammonia and water vapour liberated from the wood at the temperature employed. For example, compressed air may be introduced to increase the pressure at any stage of the process.