Linoleum

LINOLEUM, a term originally coined by Frederick Walton for material of his own invention, now used indiscriminately to describe any floorcovering having a base of solidified oil adhering to a jute canvas foundation.

Technically there are three distinct classes of floorcovering described commonly as linoleum : (a) Floorcloth, which is made by building up (trowelling) on both sides of the canvas successive layers of paint, until the desired thickness is obtained. It is then printed with a pattern and varnished.

(b) Linoleum proper, made by rolling or pressing on to the canvas an incorporated mass of linoleum "cement," cork dust, woodflour and pigments.

(c) Cork Carpet and Corticine, made in the same way as lino leum but with polymerized oil, cork dust and pigments.

Linoleum was first produced in England, in which country most of the subsequent developments of importance have taken place. The earliest patent in 1636, for "Painting with oyle cullers upon wollen-cloath, etc." was followed by the use of various mixtures of oils and resins; and, in 1751, by the incorporation of india-rubber or gum lastic. Three years later Nathan Smith established a factory at Knightsbridge for the manufacture of floorcloth, by applying a mixture of rosin, pitch, Spanish brown, beeswax and linseed oil in a melted state to canvas, and rolling it in by pressure. Subsequent improvements to cheapen the product resulted in modern floorcloth.

Walton's Patent.

It was not until 1844 that the next step towards the manufacture of linoleum proper was taken by Elijah Galloway, who softened india-rubber by heating and incorporating it with cork dust. This was rolled into sheets and marketed as "kamptulicon" which at first was cemented down, but later was rolled on to a canvas backing. Owing to the high price of rubber, however, it proved to be costly; and in 186o Frederick Walton invented a process (Eng. Pat. 209) for oxidizing linseed oil to produce a cheap rubber-like substitute. In principle, the methods used today are essentially the same as those covered by his inven tions.

The manufacture of linoleum involves the following opera tions:— (1) The production of solidified linseed oil by "Walton" or other methods (see below).

(2) The manufacture of "cement" in the case of "Walton" goods, i.e., true linoleum.

(3) The incorporation of ground cork or woodflour and pig ment with the "cement" to produce "linoleum material." (4) The application of this mixture to a canvas backing of jute.

(5) Seasoning or curing of the sheeted material.

(6) The painting (backing) of the underside to preserve the canvas.

(7) The trimming of the finished cloth.

Solidified Oil.—The four chief methods for obtaining the solidified oil are :— (I)"Scrim" Process.—Linseed oil, boiled with driers, is pumped to the top of sheds kept at oo° F, where it is mechanically flooded every 24 hours over sheets of cotton fabric (scrim). These are usually 3f t. wide by 25ft. long, and are hung about 4in. apart. Af ter some weeks' treatment, when the skins have grown to about 'in. thick, they are cut down.

(2) "Shower Bath" Process.

The oil is heated with driers (manganese borate) in a steam-jacketed pan, on which there rests a tower about loft. high, surmounted by a tank having a per forated bottom. The oil is pumped into the tank and falls in a shower and is re-circulated thus for days. It is then transferred to a "smacker," which is a steam-heated horizontal drum, fitted axially with a rapidly revolving shaft to which blades are at tached. It is half filled with the oil, whiting is added and air is blown through. The final product is run out into trays and sets to a dough-like consistency, and is stoved at about 130° F.

(3) "Wood and Bedford" Process.—The oil is run directly into a machine similar to the "smacker" previously described, and treated in much the same manner, but generally without whiting.

(4) "Taylor Parnacott" Process.—The oil is boiled with driers and agitated by compressed air until it is thick, at which stage it is transferred to smaller boilers, and the treatment continued until it becomes "stringy." The nature of this product renders unnecessary its conversion into "cement." Linoleum Material.—The solidified oil obtained by any of the first three processes is ground between rollers and heated in a steam-jacketed pan (cement pot), together with rosin (co lophony) and kauri gum. The resulting mass is a dark, homo geneous thick liquid, which, on cooling in thin layers, becomes a sticky rubber-like mass. By incorporating the "cement" with cork dust, woodflour, whiting and pigments, "linoleum material" is obtained. This mixture is intimately ground by passing it through a series of rolls and "germans" (which resemble large sausage machines) or through Pfleiderer mixers as used in paint mixing or bread manufacture. From these it is fed continuously into the "scratcher," a machine consisting of two rolls, one steam heated and the other cold, to which the material adheres, form ing a thick layer. Adjacent to this a third roll, fitted with hun dreds of sharp spikes, revolves at high speed and scratches off small particles from the layer, thus converting it to a granular or mealy form.