stucco is a term loosely applied to nearly all kinds of external plastering, whether composed of lime or of cement. The
principal varieties of stucco are common, rough, trowelled and bastard. Cement has largely superseded lime for this work.
Common stucco for external work is usually composed of one part hydraulic lime and three parts sand. The wall should be sufficiently
rough to form a key and well wetted to prevent the moisture being absorbed from the plaster, demand for smooth plastering
is still growing; just like lace finishes and other coats. Rough stucco is used to imitate stonework. It is worked with a
hand float covered with rough felt, which forms a sand surface on the plaster. Lines are ruled before the stuff is set to
represent the joints of stonework. Trowelled stucco, the finishing coat of this work, consists of three parts sand to two
parts fine stuff. A very fine smooth surface is produced by means of the hand float. Bastard stucco is of similar composition,
but less labor is expended on it. It is laid on in two coats with a skimming float, scoured off at once, and then trowelled.
Colored stucco: lime stucco may be executed in colors, the desired tints being obtained by mixing with the lime various oxides.
Black and grays are obtained by using forge ashes in varying proportions, greens by green enamel, reds by using litharge or
red lead, and blues by mixing oxide or carbonate of copper with the other materials. Roughcast or pebbledash plastering is
a rough form of external plastering in much use for country houses. In Scotland it is termed "harling". It is one of the oldest
forms of external plastering. In Tudor times it was employed to fill in between the woodwork of half-timbered framing. When
well executed with good material this kind of plastering is very durable. Roughcasting is performed by first rendering the
wall or laths with a coat of well-haired coarse stuff composed either of good hydraulic lime or of Portland cement. This layer
is well scratched to give a key for the next coat, which is also composed of coarse stuff knocked up to a smooth and uniform
consistency. While this coat is still soft, gravel, shingle or other small stones are evenly thrown on with a small scoop
and then brushed over with thin lime mortar to give a uniform surface. The shingle is often dipped in hot lime paste, well
stirred up, and used as required.