91 



PATTERNS AND FLASKS. 



Table 58 shows that nearly eleven and a half million feet of lumber are re- 

 quired annually in Pennsylvania for making patterns, flasks, and for other 

 needs of the moulders and foundrymen. Of this amount nearly 80 per cent, is 

 white pine. All of this did not go for patterns, since white pine was demanded 

 for flasks in greater amounts than was any other wood. It is, however, the 

 predominant pattern wood not alone in Pennsylvania, but throughout the 

 country at large. Its suitability is due above all to its susceptibility to hold 

 shape under atmospheric changes, to its grain being close, straight, and 

 even, with obscure figure, to its being easily worked, and at the same time 

 not so soft as to be injured by rough usage, and to its being light in weight 

 and easily portable. Since the pattern must be designed in the exact shape 

 and dimensions of the article to be moulded, the highest grades of lumber are 

 required, and, in many cases, material of considerable width is required 

 and is usually often quarter-sawed, which will not warp as easily as straight 

 sawn lumber cut without regard to grain. These are the factors which have 

 increased the cost of this species to the point of creating a demand for a sub- 

 stitute wood. Thus far no kind of wood experimented upon has been equal 

 to white pine. It will be noticed that the western white pine cut in the Rocky 

 Mountains appears in the table and also the sugar pine of California. Neither 

 of these woods can be distinguished at sight from the eastern white pine. The 

 western white pine is heavier than the eastern, and the sugar pine more 

 resinous. The kinds of wood used for patterns in Pennsylvania are as follows: 



White pine. Yellow poplar. 



Cherry. White oak. 



Mahogany. Black walnut. 



Sugar maple. Butternut. 



Sugar pine. Teak. 



Western white pine. Silver maple. 

 Redwood. 



Standard patterns, or patterns used often and therefore submitted to con- 

 siderable wear, are made as durable as possible. For these very hard dense 

 wood is required and mahogany, cherry, butternut, sugar maple, black wal- 

 nut, and teak wood the latter a foreign wood are the ones used in Penn- 

 sylvania. Large patterns, like those for moulding massive machine parts 

 can not with economy be used entirely of these woods. Only the parts that 

 come in direct contact with the sand, where the greatest wear is, are made 

 of hardwoods, the inside or filler being of a softer, cheaper wood, and one 

 more easily worked, such as white pine, sugar pine, yellow poplar, or red- 

 wood. Mahogany is the best of the hardwoods for patterns, though cherry is 

 the favorite of the domestic woods. These are of even straight grain and less 

 liable to shrink and swell when enclosed in the matrices of damp sand. In 

 addition they stand well the ramming, knocking, and rough usage a standard 

 pattern receives. Sugar maple would be more used than it is were it -not for 

 its tendency to warp. Being hard, of straight, compact structure, with a 

 capacity to wear smooth, and easily worked, it otherwise possesses excellent 

 qualities for pattern material. 



For flasks lower grades of lumber are required than for patterns. Flasks 

 serve as the frame or box, holding the sand in which to make the mould. 

 A two-part flask is used when the pattern is in two pieces, one resting upon 

 the other, the upper part is the cope, the lower the nowel. Flask material 

 does not last long, its destruction being due more to frequent burning than to 

 the general rough wear. The firing results from intense heat of the sand after 

 the molten metal is poured into the mould. Buckets of water are conveniently 



