The Back Page: The American Paper Converter April 1946

PLASTIGLAZE is the name of an impregnating solution for paper and other fibrous or porous materials. It was developed by William Lockwood, chemist for Duorite Plastic Industries at Calver City, Cal., and its purpose is to beautify and strengthen those materials which it can impregnate.

In its liquid form, it is transparent and has about the same viscosity as a very light grade of oil. It can be colored with numerous common pigments and it can be applied by pouring, brushing, spraying, or dipping.  It dries in open air within four hours at room temperature, or in 20 minutes if it is placed in an oven which is set for a temperature of 150°F. and it causes neither shrinkage nor warpage.

A test was recently made to determine the effects of Plastiglaze impregnation on an ordinary sheet of bond typing paper. The sheet was immersed in a tray filled with the liquid for approximately 15 minutes; then it was laid out flat on a board which had been covered with floor wax to prevent sticking.  Drying took place in slightly less than two hours and a subsequent examination revealed the following facts;

Strength Improved

1. The sheet had a hard, glazed surface similar to that of celluloid.
2. Although it could be bent without cracking, the sheet had vastly improved strength properties and could support several times its own weight without deflection. This was ascertained by placing one end of the sheet between two books and loading the other end until it definitely sagged.)
3. Small pencil marks that had been placed on the sheet prior to impregnation could not be removed with an eraser.
4. The sheet softened and charred when exposed to an open flame, but would not readily support combustion and was not affected by temperatures of less than 200°
5. The sheet did not soften when it was immersed in water and it had very good resistance to acid and alkali solutions.
6. The weight of the sheet was increased by approximately 25 per cent.

Box Held 200 Pounds

In another test, a small cardboard box, which had a height of two inches, a width of three inches and a length of six inches was found to have sufficient strength to support the weight of a 200-pound man after the box was thoroughly impregnated with Plastiglaze.

When strength properties are not as important as appearance, Plastiglaze can be used like varnish and will form a glossy surface coating on even such a porous material as plaster after one or (at most) two applications.  In order to do the same job, varnish would necessitate at least six applications.

Plastiglaze is a particularly desirable brushcoating material.  Mr. Lockwood states, because its low viscosity and high flow properties enable it to completely obliterate brush marks prior to drying.

Utilized on Lamps

Cardboard laminates have been made by impregnating and stacking 1/32”-thick sheets without pressure and tests have shown that they have excellent tensile strength and much more flexibility than plywood.

At Process Arts Company of Los Angeles, Cal., transparent Plastiglaze is now being used in the manufacture of novel paper and plaster lamps.  The bases of the lamps are plaster casts which resemble carton characters and the shades are paper mounted on a light-weight wire frame and decorated with decals. A single spray coating of Plastiglaze gives both units a durable, high-glass finish.

Another Los Angeles Company is currently preparing to manufacture novelties such as flower pots by impregnating cardboard with pigmented Plastiglaze. Although the pots will cost only a few cents each, they will have a much longer life than ceramic flower pots because they are extremely flexible and can be dropped from a height of twelve feet onto a cement floor without breakage.

Various Effects Used

Plastiglaze is made by combining thermoplastic and thermosetting resigns in the presence of any one of several common solvents.  Therefore, it can be changed from a transparent liquid into a translucent or opaque colored material simply by mixing with various quantities of appropriately soluble dies.  Mottled color effects can be attained by creating a Plastiglaze emulsion with incompatible pigments, immediately prior to coating or impregnating.

Because it is an air-drying substance, Plastiglaze should be kept in tightly-sealed containers whenever it is not in use. However, if it should become too viscous, it can be readily thinned with solvents.

Possible applications of the new material in the paper manufacturing industries are innumerable. For example:

1. It would greatly reduce the cost of manufacturing glossy, high-quality cardboard.
2. It could be used to produce washable wallpaper which is much less expensive than any other wallpaper of this type now on the market.
3. It will greatly increase the life of valuable documents.
4. It will minimize the fire hazard that is normally encountered in work with paper products.
5. It could be used to manufacture strong, attractive boxes of various types.
6. It should be especially suitable for the finishing of papier mache articles.
7. It might improve the quality of many of the pulp-molded products now on the market.
8. It will probably find many applications in the field of contact laminating.

Expect Cost Reduction

The cost of Plastiglaze at present is about the same as the cost of conventional lacquers and enamels. However, this can probably be reduced when the compound is produced on a larger scale.  Mr. Lockwood believes.

The development of Plastiglaze began during the war for the purpose of increasing the usability of non-critical materials in American war plants, but the preparation did not become commercially available until early in 1946.

History Report

In 1946, prior to RDG Media ownership, The American Paper Converter (now known as PFFC) was published monthly by the Howard Publication Company. Subscription cost were: $3 for one year, $5 for two years, single copies $0.35.  International subscriptions were also offered to Canada and Pan-American Postal Union for $3.50 and $6, as well as “Foreign” for $4 and $7.