The New Apprentice

The New Apprentice

After so many years of pursuing my craft of plaster I have decided to embrace the challenge of learning an equally noble craft, architectural stone carving as a student at the American College of the Building Arts. And make no mistake my friends, it is a challenge. Whatever experience I may bring from my craft of plaster is negated by the years of acquired habits contrary to my new medium of stone. Plaster is soft, Stone is hard. Plaster is fast, Stone is slow. Plaster is additive, Stone is reductive. I'm in a bizarro world, ground zero, and my arm hurts.

Even more disconcerting, my reputation is on the line. Whilst I teach my sophomore students the art of plastering I transform later in the week into their fellow student, particularly humbling as I'm yet to especially distinguish myself as having a natural aptitude for the art of stone carving. If nothing else it has been a poignant reminder of what it is like to start from scratch and an admonition to empathize, exercise patience and be quick to recognize and praise effort or improvement. I like to think being a student is helping me to be a better teacher.

Please don't get the wrong impression. I'm actually having the time of my life. Learning alongside these young men is energizing. Being taught by a stone carver raised in the tradition of Lincoln and Wells cathedrals is a singular privilege. So what have the lads and I learned in BAAS (Building Arts Architectural Stone) 201, during the Fall semester of 2013? The following is hardly an exhaustive list but chronologically encompasses a few of the highlights:

1. Accurately measuring the profile of an existing stone
2. Drawing and drafting a profile
3. Splitting a large stone by hand with plug & feathers
4. Creating a flat surface with traditional hand tools
5. Using a template to apply a profile to stone
6. Carving an ovolo in a softer Texas limestone
7. Masonry arch study
8. Carving a cyma recta in a medium hardness Indiana limestone

Measuring and Drawing

Student tracing a profile

 from an existing piece

Accurately measuring the profile of an existing piece of stone is not as simple as you might think. With six students we initially came up with six slightly different results. Often the stone is damaged or weathered and some judgments have to be made. Methods included applying a surface profile gauge, directly measuring the individual surfaces and tracing the profile directly against a piece of paper. In the end a combination of several methods, occasionally revisited, proved to be the most accurate approach to capturing the profile.

Next we headed to the drafting studio for an exercise in shop drawing skills. Taking our measured profile for reference we imagined two turns and a stop, providing the “top bed” and all four side views, using traditional methods of hand drafted projection.

The completed shop drawing

Splitting Stone and Creating a Flat Surface

 

Student splitting

a large block of limestone

with plug and feathers

Pencils down, into the field we went. First we examined the limestone as received from the quarry, discussing the type of equipment they use to cut the stone and identifying the “bed” or natural grain resulting from the successive layers of sediment that formed the limestone, in this case from a quarry near Austin, Texas. After a number of measurements related to our original piece we proceeded to learn how to split large pieces of stone. The first step is to drill a series of holes about 6 inches apart and to a depth of approximately ½” from the base of the stone. Any closer risks a blowout on the bottom of the stone. Next, “plugs”, wedge-like piece of steel are driven between “feathers” into the holes with a steel hammer. This should be done patiently being careful to listen to the ring of the impact. A higher tone indicates a tight fit. The resulting break is surprising clean, within a ¼” accuracy on the specific Texas limestone we were working with.

"Flatness"

Finally everything was set to begin learning stone carving in earnest. The first goal was to establish a line with a steel scribe around the stone to then cut a flat planar surface to that line. That process exposed us to the full range of hand tools. First a “pitcher” was used with a steel hammer to quickly remove large masses of stone. The steel hammer transfers considerable force into the stone. Other tools for roughing in were introduced such as the “punch” and “claw”, each removing less and less material while offering more control. Finally, as we got closer and closer to our scribed line tools for more refined work such as the “bolster” and chisels were used. These are designed to be used with a nylon mallet that absorbs much of the impact, allowing for greater precision. Frequently checking our work with a steel straight rule, we were all able to achieve the goal of a flat surface.

Student working his way to the line with a "punch"

 

Using a Template to Carve an Ovolo and Cavetto

 

The next step was both exciting and a wee bit intimidating for us all. It involved the convex ovolo curve, the concave cavetto curve as well as two inside corners. Using our previously drafted profile we cut out a template in cardboard. That was placed against the appropriate edges of the stone and scribed in with our steel point or scribe. A hard lead pencil was then sharpened and traced in the scribed lines to make the lines more easily visible. Rather than attempting to approach the curve directly we approached the ovolo gradually in as series of straight planes. 

Applying the template

Approaching completion

Masonry Arch Study and Carving a Cyma Recta

After the mid-term exam it was back to the drafting studio we participated in a preliminary study, a preview of the Spring semester goal of constructing a masonry arch. Four arches were constructed. The first two were single point or radial arches. The first of these at top left is commonly known as a “Roman” arch. Below is another radial arch integrated into an ashlar masonry façade. The top right features a three-centered arch closely resembling an ellipse in curvature. The last one at bottom right is a four-centered or Tudor arch. I'm certainly looking forward to putting this study into practice next semester.

Elliptical Arch

Roman Arch

Rusticated Roman Arch

Tudor Arch

 

Zinc profile

Our ultimate assignment for the semester was to carve a more complex moulding that prominently features a cyma recta or upright S-curve. This is a practical exercise as each student is assigned a piece. Together the pieces are to be used in the construction of a new sign for the college. The Indiana limestone was much harder than the previous Texas limestone. We used electrically operated grinders to cut off and flatten some of the larger sections before finishing with hand tools. As this work was to last longer and be completed outside we opted for a more durable zinc template. A progress photo is at the top of this article. Completing the moulding involves turning an outside corner and will be our first order of business in the Spring semester!

Plan and elevation for the moulding as well as a shade & shadow study

Contributed by Patrick Webb