Plastering, by J.T. Sawyer

Plastering
by J. T. Sawyer
Reprint Donhead Publishing, Ltd.; Dorset, UK; 2007
144 pp; clothbound; 165 illus.; $60
ISBN 978-1-873394-83-0

In their introduction to Plastering, Jeff Orton and Tim Ratcliffe note that J. T. Sawyer wrote this textbook during the mid-20th century. During the 1930s and '40s, his homeland, the UK, was deeply involved in the Second World War – a period when new construction was halted while builders engaged in battles at home and on the European continent. In America, the plight of the building trades was further complicated by the Great Depression, which limited the transfer of skills from "father to son" for a similar but longer time period.

Fortunately, Joe Sawyer came from a family of plasterers, and he taught the subject at a technical college in London, England. His book, here reprinted by Donhead Publishing, underscores his technical clarity and teaching ability.

Over time, several books and articles to do with plain and ornamental plastering were published, including one dating from the late-19th century. As photography became the contemporary illustrative mode, drawings became secondary and, in the opinion of this reader, information became more difficult to follow. With paperbacks in particular, photographs were often unclearly reproduced. However, Sawyer uses no photographs, and his freehand drawings are crystal-clear and simple to follow.

Language peculiarities are not an issue. Terms such as "rebates" and "striking off lines" are understandable, even though we may refer to them differently in America. No doubt, working for decades with similar handmade tools allows journeymen to understand the drawings at a glance. However, due to the clarity of the visuals, even beginners using their own tools for the first time will gather skills quickly.

For example, the chapter on running moulds (molds) perfectly illustrates interior and exterior cornice molds, twin horsed panel molds, hinged molds and peg molds. Following the written descriptions while viewing the drawings makes it abundantly clear that the author was a great teacher and a superb craftsman.

While most pieces of equipment are standard in today's tool kits, some seem out of date, especially the wooden hawk. Most suppliers market metal hawks from which the handles unscrew (as do rubber pads) for ease of packing. Small tools are for sale even at lumberyards which supply plaster products.

In the comprehensive chapter on materials, Sawyer touches all bases and seems generally correct. When discussing lath work, he suggests that wooden members, whether riven or sawn, are "almost traditional, so great is the length of time over which laths have been successfully used." In restoration projects, however, it is the experience of this reader that wooden lath is indeed satisfactory without deleterious effects which fracture the scratch coat keys: water intrusion, building settlement, nearby blasting, heavy traffic, introduction of modern electrical, plumbing, HVAC services, etc.

For whatever reason, a large quantity of broken keys often causes ceilings (and walls) to fail. Contemporary techniques, developed in Sawyer's lifetime, involve supporting ceilings from below later to be injected with acrylic adhesives into each lath in each joist bay bonding lath to scratch coat. Laths are secured to joists stabilizing the ceiling.

According to Sawyer, expanded metal lath is superior to wooden members because it is fire-resistant and bituminous coated to avoid rust. It is difficult to disagree that metal lath, as viewed from above a 1920s domed theater ceiling, is far superior to wooden lath, no matter how skillfully wooden lath is applied.

Later in the materials chapter, Sawyer discusses gelatine, or hide glue, for use as a flexible molding material in the manufacture of ornamental plaster products. Glue is melted in a double boiler and poured over a model. After cooling, the mold is treated with alum, whiting and a separator, following which plaster casting begins. Plaster is exothermic and can melt the glue surface especially during summer months, however plaster may be gauged using ice water (blocks of ice are often added to drums of water) causing the plaster to set before it heats up. Glue can be melted again after casting activity, which is an added economical benefit.

Recently, several companies have developed pourable and thixotropic molding rubbers to substitute for hide glue products. The rubbers may not be re-melted for new molding but, with few exceptions, they have a significant "library" life. Cost is no longer an issue as glue materials are now priced equal to molding rubbers. Several urethane formulae have been used for over 35 years and remain in excellent condition. Some new silicone rubbers require no initial release agents and they have rapid cure sequences, which vastly reduce time spent at work sites. Platinum cure rubbers are expensive but hotel, parking and meals expenses are often unnecessary using fast-set materials. A successful ornamental plaster studio should have the capability to use all products, new and old, for maximum work efficiency.

The chapter on geometry and drawing is exciting to ornamental plasterers who have built moldings following Classical elevations and sections. For example, the Equilateral Gothic Arch (Fig. 133) is typical and was used to reproduce bench-run niche head moldings for the restoration of the fire-ravaged Silverton, CO, Town Hall. Figure 142 shows a semi-elliptical arch frequently used as part of overdoor moldings in New England Federal houses. Nomenclature is often useful to describe polygonal forms. And this chapter advises plastering students to practice drawing sections of cornice moldings and to "memorize the names of the various parts that form a complete molding." Sawyer's visual description of raking moldings (as often used in broken pediments atop Classical architecture and furniture) is simple and clear, as illustrated in Figure 159.

For the ornamental plasterer, Sawyer's chapter on benchwork will reveal simple additions to an already full vocabulary. A straight length (Fig. 113) is often run over a core which prevents slipping and reduces the weight and quantity of plaster; the clay and nail accomplishes the same result. Figure 114 illustrates model-making techniques for decorative cornice moldings; visits to ornamental plastering studios will reveal this procedure in action on a daily basis. As for casting, Sawyer describes mixing plaster in two distinct batches: "firstings and seconds." This activity is for the purpose of accomplishing all necessary procedures before the plaster sets. Another procedure is to fully gauge the required quantity and remove the finishing amount before the mix is stirred. Clearly, mixing accelerates the setting process. Plaster will adhere to itself if applied in the same gauge. Presumably, Sawyer's reference to canvas means burlap to Americans.

Plastering does not conclude with a glossary, which could have been helpful. Rather, together with Orton's and Ratcliffe's introduction, the preface and biography of J. T. Sawyer illustrates the importance of this handbook.

It should be noted in this review that Donhead Publishing, Ltd. (See Traditional Building, April 2007, page 150 for a review of Donhead's Modern Practical Masonry.) is a significant entity in the field of building conservation whose mission, not unlike that of the US National Park Service, is to document preservation procedures. A visit to their website (www.donhead.com) reveals titles such as Conservation of Historic Buildings and their Contents, Old House Care and Repair, Survey and Repair of Traditional Buildings, and Measurement and Recording of Historic Buildings among more than two dozen publications, both contemporary and reprints.

For the plasterer (both flat and ornamental) it should be noted that Donhead, through its publishing efforts, encourages a comparison between the Sawyer handbook and William Millar's seminal Plastering Plain and Decorative of 1897. TB

Sculptor David Flaharty runs a Philadelphia based ornamental plastering studio that undertakes architectural conservation and restoration in addition to period design, manufacture and installation for new construction. Trained at Rhode Island School of Design and Cranbrook Academy of Art, Flaharty specializes in 18th-20th century decorative enrichments and concentrates on ceiling medallions, cornices and ornamental metals. With 25 years experience in the field, Flaharty conducts illustrated lectures, hands-on demonstrations and consultation services. Together with restorations at historic houses, significant projects include ornamental plasterwork in the American Wing period rooms at the Metropolitan Museum of Art, the Diplomatic Reception Suites at the U.S. Department of State and the White House.

JUNE 2008 » book review