grey middles and poor facings, but it is possible to obtain a good class of boards at a moderate price, and it is far more satisfactory to keep a stock of material of good appearance than to obtain the lowest quality possible. White cardboards should be rigid, of good colour, smooth, and should be so well sized as to be suitable for post-cards or similar work. Pasteboards can be obtained in various substances, being described as three-sheet, four-sheet, etc., but there is no point system in card thicknesses, as one maker's six-sheet will be the same as a four-sheet of another manufacturer. A very fair range of colours can be obtained in paste-boards, but if a special colour is desired a making order is frequently necessary to ensure sufficient of the special facing paper.
Triplex boards are not made in the same variety of thickness or colours as pasteboards. It is not possible to build up the substance in triplex and to dry the web successfully in the thickness of the heavier pasteboards, but it is possible to procure very good triplex boards with the attributes specified for paste-boards.
The better qualities of cardboards will be found suitable for most classes of printing, even for half-tone work, but if three-colour blocks are to be printed, coated boards are necessary. Chromo boards, one- or two-sided, are obtainable from three- to twelve-sheet in substance, and on these any class of work will stand well. Owing to the burnished surface of these boards show cards keep clean for a much longer period than when ordinary cardboards are used, and frequently varnishing can be dispensed with if enamelled boards are not exposed to weather. Coated boards must be handled with care at all times, as the surface is sensitive to grease and moisture, notwithstanding its
