Document jm4J3LgJ2yGppN23R3reqeLLZ

DAKPIBO KXXS&AL ni5SB The above description applies particularly to the damping of slag wool in order to facilitate its application by the Spray Process* The discovery that damp slag wool would not bounce off in the same way as the dry matorlal when sprayed in the usual way through our equipment, was made by /!r Wilson in August 1950* ia the course of trials involving asbestos and slag wool blends. The method used was to place the fibre in our patented damping drum, known to Gill, Jennings & Every under the description ''Damping fibre I." It occurred to me that this might provide the answer which T.l.C.Co. were looking for* and in order that we should not be left.out in the cold were they to discover the same thing* itTbccuzred to me that we might apply for a patent, and 1 discussed this with Mr. Every when seeing him on other matters at that tisa. If. Every thought there was something in the idea, and a draft specification was submitted by Kr Wilson during my absence in South Africa, of which he sent me a copy. This sot only dealt with damping, but with the addition of Portland cement in the drum mixer, which overcomes the difficulty of incorporating Portland esment with slag wool in the dry state* so that it is possible to spray and produce a fairly satis factory coating with slag ircol and Portland cement alone, and all that anyone wishing to copy us would have to do would be to devise a drum, or some mixing machine very similar to our own, throwing in a few handfuls of fibre with a small amount of Portland cement, before feeding it to a standard spray machine of our old type without damping gear - to produce dustlesa low-priced coatings, information which, 1 fear, might quite well bring a boat of imitators into our field of operation* all over the world* In correspondence, Gill* Jennings are of opinion that we might get a satisfactory patent, presumably in Groat Britain, but this does not automatically follow in Prance, the United States, and elsewhere. Also, they point out that reference to Portland cement has been made in earlier applications* which is quite correct, but here we merely refer to ^mixing of Portland eement," without revealing how the mixing Is done, whieh is the all-essential feature of our seeret. Anyone seeing the specification would presumably - to judge by results to date - try and six fibre and caaent in a Gardner or similar mixer, which is quite useless because the cement is not driven into tbs fibre bundles, ao that it asperates out into the hopper of the machine* and any that does come out with the fibre is usually separated out in the blowing through the nosale, which not only results in the cement not reaching the coating, but in a great deal of dust. Damping of the Portland cement overcomes this difficulty, and causes it to stick to the fibre so thst it arrives is position in the eoatisg* It should eoeordingly be cleer that anything but a eastiron patent, providing world-wide cover, would result is much more harm than good* Iteeh the same applies to the less complicated idea of pre-damping slag wool before spraying it. As ay report on ay recent visit to America will show, we arc faecd with e number of secondrat# Imitators who, beesuse they cannot obtain eabestoa fibre* are doing their best to spray slo wool. These people f\ '4\ _$ JZ W**** 'AKW* ] 2 * ere net quipped with extensive research laboratories, and it is, therefore, unlikely tbit they will discover the secret unless ve point it out to then* filamentary esution suggests that, vero we to consider it desirable to take out a patent on the damping of mineral fibre, e should first of all thoroughly investigate the possibility of obtaining a good watertight patent in the United States bsfore taking any active steps elsewhere. The above should not be taken as an indication that we are at any moment likely to be put out of business by someone who may asks the eaao discovery. Slag wool costings, at best, ars not vsry satisfactory or permanent. 5:1:1951 NLOi/KL 8.U Colbey O '/ V.