The cutting of sheets to size and shape can be effected without difficulty, since the steel-coating is very thin (usually 012 in. thick). Either metal-cutting saws, or wood saws having little or no set-circular, band, or fret-can be used for this purpose. A wood-working saw without any set, will be found to be quite satisfactory.

Holes in panels, such as " lights " in vehicle sides, can be cut on the jig saw.

Where machine tools are not available, panels can be cut to size by hand " roofing " saws, or hack saws, whilst small compass saws will cut holes with easy and rapidity. Naturally, care must be exercised in hand sawing, particularly at the commencement of the cut. When the steel is on one side only of the sheet (Type 1.GS.12.) the metal should be placed upwards, whilst with Type 2.GS.12. (steel on both sides) the lower metal face should be supported whilst sawing.

Nailing. Drilling and Punching. -Wire nails may be driven through Plymax sheets without previous drilling.

Holes may be drilled with an ordinary twist drill. When drilling, it is advisable to hold a piece of hard wood to the back of the sheet. When countersunk screws are to be used, holes may conveniently be punched using a punch and bottom die. Such holes are countersunk in the punching.

Ordinary chisels and gouges of the socket type, which allow of a mallet being used, will be found quite suitable for cutting Plymax. In cases where the position of holes and slots can be pre-determined you can obtain sheets already punched and slotted.

Special Tools For Plymax

It is not essential to obtain any special tools for cutting Plymax ; but, if large quantities of the material are being dealt with, it may be found to be more economical to utilise saws which have been specially designed for Plymax by Messrs. Sanderson Bros. & Newbould Ltd., Sheffield.

Soldering

Ordinary soldering fluxes may be used and an iron which is not too hot is recommended, in order to overcome the tendency of the metal to buckle with the heat. This tendency can be still further prevented by the use of a low melting point solder. Plymax will be found to tin readily.

Painting

Although the steel faces of Plymax are high-class galvanised sheet, in exposed positions it is advisable to paint the surface to prevent corrosion. In protected and indoor positions it should not be necessary to do this for some years, depending, of course, on the conditions on the site.

No difficulty is experienced in the painting of Plymax. The galvanised surface should be allowed to weather for a few months, if possible, and should then be thoroughly freed from grease and dirt. This is effectively done by scouring with pumice and turpentine. A good metal primer should then be applied, after which ordinary painting treatment can be followed.

In the case of vehicle panels, it may be impracticable to allow sufficient time for the sheets to weather, in which case they may be artificially weathered by sponging over the surface with a weak solution of copper sulphate (blue vitriol crystals), strength about 1/4 lb. to a gallon of water, as this develops the necessary key for the proper adhesion of the priming coat. When dry, the surface should be lightly wiped over and the metal primer applied.

If desired, panels can be artificially weathered in this way by the makers, before despatch.

Most reputable paint manufacturers can supply good metal primers.

Types

Plymax can be supplied with faces of various metals- steel, zinc, copper, aluminium, and others. It is made in two main types-Plymax with one metal face only, and Plymax with two metal faces, that is, with a core of plywood and metal on both surfaces. These types, steel faced, are known as 1.GS.12. and 2.GS.12 respectively. For Plymax faced with other metals there are other designations.

Size Of Sheets

Standard sizes are as follows : Steel-faced Plymax from 48in. x 24in. up to 132in. x 36in. Aluminium - faced Plymax from 48in. x 24in. up to 120in. x 48in. Thicknesses from 1/8in. to 3/4in. are standardised. For special purposes over-thicknesses can be supplied.

Curved Surfaces

Plymax can be bent readily to simple curves, but for this purpose Plymax with one metal face only should be used, and the metal should be on the outside of the curve. To meet special requirements Plymax with two metal faces can be manufactured bent to standard curves.