Repoussé Pitch Bowl Embossing & Chasing Chisel Linework: Chasers Pitch, Punches & Plastic Flow

The secret to achieving breathtaking three-dimensional relief in Mexican metalcraft lies not in steel anvils, but in the formulation of chaser’s pitch (brea de orfebre). If sheet metal were hammered directly over solid steel or hard hardwood, the metal would thin out rapidly, tear along sharp edges, and deform uncontrollably. Pitch provides a dynamic, semi-elastic backing that supports the metal uniformly, yielding under hammer blows to permit deep stretching while offering enough firm resistance to define crisp lines.

In Michoacán workshops, master smiths formulate their own pitch according to closely guarded recipes. The foundation is natural pine rosin (brea de pino) harvested from the vast highland forests surrounding Pátzcuaro. Sifted red clay brick dust (barro rojo molido) or plaster of Paris is melted into the resin to provide structural stiffness and body. Finally, a small proportion of rendered beef tallow or mineral grease is stirred in to impart elasticity. In summer, smiths decrease tallow to keep the pitch firm; in winter, they increase tallow to prevent brittle fracturing.

The physical transformation of flat sheet metal into architectural sculpture begins with repoussé (repujado)—hammering from the reverse side to push the metal forward into three-dimensional space. The molten pitch is poured into a heavy, cast-iron hemispherical bowl that rests securely upon a round leather collar filled with sand. This ball-and-socket configuration allows the craftsman to rotate and tilt the working plane in any direction with a touch of the elbow.

After annealing the silver or pewter sheet to maximum softness, the artisan warms the surface of the pitch with a torch until it turns tacky and embeds the metal sheet securely. Working from the back, the craftsman strikes smooth, polished brass, horn, or hardwood punches with a flexible-handled chasing hammer. Under controlled blows, the metal stretches into the yielding pitch, raising bold, voluptuous domes for floral blossoms, scrolled leaves, and decorative fruits without thinning the gauge catastrophically.

Once the primary volumes are raised, the sheet is removed from the pitch, cleaned, annealed, and remounted face-up for the second phase: chasing (cincelado). Crucially, before embedding the face upward, the craftsman fills the deep hollows on the underside with molten pitch. This solid backing ensures that when the artisan strikes the front face, the raised relief will not collapse or flatten under tool pressure.

With the metal firmly bedded, the smith employs a vast array of specialized steel punches—often numbering fifty or more in a master's kit. Using narrow, curved liners (trazadores), the artisan walks the tool across the surface with continuous, rhythmic hammer taps, displacing metal laterally into razor-sharp contour grooves. Planishers smooth background ripples, while textured matting tools strike thousands of microscopic indentations into the recesses, creating a velvety, light-absorbing contrast against the polished high-relief surfaces.

Releasing the finished metalwork from its pitch bed requires delicate thermal control. The artisan passes a gentle, bushy torch flame across the surface of the metal until the pitch underneath liquefies. Using long-handled tongs, the craftsman lifts the hot plate and allows excess black pitch to drain back into the bowl. Any residual resin clinging to the metal is burned away or dissolved in a bath of mineral spirits, turpentine, or citrus solvent.

The chased plate is then scrubbed with warm soapy water and brass wire brushes to reveal the pristine, unstained metal. Around the outer perimeter of the design, the smith uses polished planishing hammers over a stake anvil to true up the border flanges. The finished plate is now ready to be trimmed, folded around architectural timber carcasses, or patinated with traditional mineral oxides to complete the masterpiece.