Paper-parting
The Encyclopedia of Founding (1892)
Ordinary moulding-sand will not adhere to paper that is free from substances of a gummy or gluey nature, no matter how hard it has been rammed thereon. For this reason it makes an excellent substitute for parting-sand at parts of a joint where it is difficult to apply the sand in either a wet or dry condition. See PARTING; JOINT; PARTING-SAND. Paper Sheathing for Studs.--It is sometimes convenient to use a plain stem chaplet at parts of a casting where there is not sufficient body of metal to partially fuse, and thus fasten it. In such a case the surrounding cast iron is chilled, and it is with great difficulty that a thread can be made by which to insert a plug. If, before the chaplet is inserted in the mould, a thick layer of paper be glued thereon and an extra coat of silver-lead applied, the hole will be clean and the metal soft for tapping. Paraffine is a product of the distillation of wood (especially beech-wood), coal, and petroleum. It is a white, hard, inodorous, tasteless, crystalline solid, resembling spermaceti. It melts at 111 deg., and is formed into candles, which burn with a very bright flame. It is a pure hydrocarbon. Paraffine-oil is the term given to the thin oily matter given off during the process of distillation. See PETROLEUM. Parallel Straight-edges are two straight strips of wood or metal, of equal widths along their length. By setting them edge up, some distance apart, on a pattern or mould, and allowing the eye to range along the upper edges of both, any deviation from a true and even surface is soon discovered, the eye being very quick to detect any discrepancy. See LEVEL; BED.
What Has Changed in the Last Century
When the Encyclopedia of Founding described this trick in 1892, moulding was overwhelmingly a hand craft: sand rammed by hand into flasks, joints dusted with parting-sand, and a slip of paper used where loose sand would not stay put. Most production casting today is done on machines with chemically bonded sands (resin and no-bake systems), lost-foam and investment processes, or die casting, and where green sand is still used the parting agent is a manufactured powder or a sprayed liquid release rather than paper. The chaplet advice has aged similarly: chaplets are still set to support cores, but they come tinned or plated from a supplier, and the entry's "extra coat of silver-lead" reflects a time before lead was driven out of foundry practice on health grounds. Small jobbing and art foundries still rely on hand ramming, so a moulder reading this in 2024 would recognise the problem even if not the fix.
Written for this edition, 2026.