FIREPROOF TIMBER

Hauraki Plains Gazette, Volume 47, Issue 2667, 8 September 1937, Page 6

FIREPROOF TIMBER

A NEW DEVELOPMENT DESCRIPTION OF PROCESS IMPREGNATION OR SPRAYING. DEVELOPMENT of interest to architects, builders and timber merchants as well as’to-the general public is the perfection of a new agent for the fire-proofing of timber, plywoods and wallboards. The qualities and uses of this chemical (to which the name of Faspos has been given) so far as it affects timber and plywoods are described in a booklet recently issued. It is claimed that with Faspos, timber can be cheaply and efficiently fireproofed by established methods and to a degree which fully satisfies the fireproofing tests specified by the British Standards Institution. The chemical should enable wood to be used in many instances in which its inflammability has previously been a serious disadvantage.

The chief danger of wood is its tendency to feed the flames in the early stages of a fire, so that attempts at fireproofing have nearly always concentrated on localising the burning. Faspos is said not only to achieve this by forming. a protective glaze over the surface of the charcoal, but also prevents the flames of the discomposition productions.'

The new compounds are available as three types: No. 1 for general purposes and interior fireproofing; No. 2 for external treatment;, and No. 3 for brush or spray treatment of erected timber. All three are applied in the form of solutions in water and their basic constituent is mon-ammonium phosphate, the decomposition of which is responsible for their fireproofing effect. Both the solutions themselves

and the products of their decomposition by fire are non-poisonous and non-irritant, and the results of tests cited in the booklet show that the corrosive effect of the treated timber on metal structures is negligible. Moreover, the fireproofing effect is said to be reasonably permanent, even under weathering.

The solutions are easy to prepare and the booklet gives useful tables of specific ' gravities and Twaddell densities of the solutions specified.

The method of fireproofing with Faspos recommended by the manufacturers as giving the best results is

that of pressure impregnation. This can be .carried out by a process similar to that used for creosoting and the

design and operation of a suitable plant is given. Alternative methods of hot-and-cold steeping and surface treatment by brushing or spraying are also dealt with.

After-treatment of the processed timber is not seriously influenced by any of these methods of application, while Faspos solution permits of stack or kiln drying of timber in the usual way.

The cost of producing seasoned, fireresisting timber by these methods depends largely on the facilities at the operator’s disposal, but, taking as a basis the quantity of Faspos as 12 per cent, of the original weight of the timber (which is the manufacturer’s recommendation for correct proofing) the cost of proofing a soft wood by pressure impregnation, followed by kiln drying, works out at about Is lOd to 2s per cubic foot, or £l5 to £l7 per standard. The cost of working a hot-and-cold soaking process will probably be of a similar order, while that of a painting or spraying process has been estimated at about Is 6d per ICO square feet including labour costs.