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Corbin Bronze Blog

From the studio of Tom Corbin

Elle Decor

December 2011

High and Mighty

Shown: Alexandra II Pedestal Table

Interiors by Ray Booth

Photography by Pieter Estersohn

View all Occasional Tables

Interior Design

Fall Market Tabloid 2011

Accessories

“Modern Primitive, There’s something old, something new to these rough-hewn accents”

Shown: Woman at the Center

View all Sculptural Accessories

Spaces Kansas City

Holiday 2011

High and Mighty

Shown: Jazz I

View all Medium Sculptures

BH&G Renovation Style

Winter 2011

12 Ways to Spruce Up Your Fireplace

Shown: Zigzag Andirons

View all Andirons

KC Magazine

September 2011

Perfect Harmony

Shown: Corbin miniatures

Interiors by Kyle Wells Design

Photography by Bob Greenspan

View Corbin miniatures

Architectural Digest

September 2011

Elements of Surprise

Shown: Alexandra Floor Torchieres

Interiors by Robert Couturier

Photography by Tim Beddow

View all Floor Lamps

The Independent

August 2011

Sculpting Young Audiences

Shown: Open Windows, exclusively for Kansas City Young Audiences

Contact Mary Needham for more information or to purchase, 816-531-4022  mneedham@kcya.org

The New York Times Style Magazine

Profile in style, Erica Reid

Shown: Alexandra Floor Torchieres

HGTV Selling New York

High and Mighty

Shown: Horse and Rider (sold out)

Taking inspiration from nature, Tom’s flowers are a Corbin hybrid with expressive gestures and sunny dispositions ~ no watering required. Inspired by the new sculptural accessory, Flower Study, Tom has created 3 new “Botanicals” shown in progress below.


Flower Study

Botanica

Inspiration sketch

Refinements to design
 Flower arranging

 The finished design, shown with sprues added for casting

Cinque Fiori

Multiple single stem flowers arranged on a base
 The first three stems are placed and manipulated, creating movement
 All five stems grow in perfectly organic asymmetry

 Flowers, which will be cast separately are removed for molding

Tre Fiori

Sketches of the three stemmed design

Three flowers and a sweet hummingbird

 Red wax sprues are added before molding for castability
 A bed of clay will enable Tom to mold the first half
 Rubber mold material
 The second half

La Promenade Female will illustrate the final highly important step in the casting process: patina.

Part 1:  Sculpting

Part 2:  Molding

Part 3:  Foundry

Part 4:  Casting

The Art of Patination

The beginning of patination was introduced in 12thcentury Asia and toward the end of the dark ages in Europe. The patina artists developed methods of mimicking the mottled greens produced from years under the sea, the vibrant blues of being buried for generations in an alkali soil and the rich reds and browns which accented the bronzes in more acidic regions.

The patineur will apply chemical solutions to achieve the desired color. Each patina is intrinsically unique, giving the bronze exclusivity and enhanced value.

Individual solutions are sprayed onto the sculpture one layer at a time creating rich, dimensional color.

“Liver of sulfer” is used, making the surface nearly black.

An abrasive pad is used to scrub back the surface, revealing “natural” bronze highlights on the outer surfaces while leaving the dark color in the recesses. To achieve a Corbin Bronze Natural Patina, the process is completed here by brushing on paste wax.

For a green/brown patina, as seen on most Corbin sculptures, several more steps are taken layering brown and then green patina formulas. Below, ferric nitrate (brown) to start…

A cupric nitrate formula is sprayed on the surface which will turn the surface green.

A coat of paste wax is applied while the surface is still hot, making the green partially recede while the rich browns emerge.

See the finished work: La Promenade Female

Photography by Ron Berg

Now we’ve made it to actual bronze casting, the most intriguing step in the foundry process, where the term “lost wax casting” comes from. To read earlier installments, click here:

Part 1:  Sculpting

Part 2:  Molding

Part 3:  Foundry

Bronze ingots are placed in a large crucible.

The crucible is placed in a furnace where the ingots will be melted to a temperature of approximately 1900 ° F.

The wax, encased in ceramic shell, is heated in a kiln (below). The wax is melted out, leaving an empty ceramic mold ready to receive the molten bronze.

The ceramic molds are placed in sand beds that keep the molds upright.

A highly choreographed and careful team sets up to pour the molten bronze.

The bronze will cool inside the ceramic mold.

As the bronze cools, the mold will even begin to split due to the change in temperature.

Bronze hammers and mallets are used to carefully chip away the ceramic shell.

Everything that was wax is now bronze, including the sprues or channels shown below on the left. This is an example of Man I (a tall sculpture), which is about 6′ tall once assembled.

The rough bronze casting is fully revealed and sprues are carefully removed. Below, chasing tools are used on a medium size sculpture, Man Study. “In the finishing area, opaque barriers shield the eyes from welding torch sparks. This is where pieces are meticulously matched to the original, and any deviations are carefully reworked to reconcile the finished piece to the artist’s initial intent. In this way, every piece, even in a series, is truly an original.” (an excerpt from Tom Corbin The Inevitable Artist by Beverly Bellinger).

Most sculptures larger than about 20″, depending on the form, are cast in several parts. Skilled artisans at the foundry will carefully weld the pieces together leaving no visible seam.

Woman I is being assembled below.

Once the sculpture is fully assembled and chased to replicate the original, the next step is to get a completely uniform surface so that the surface can accept the patina.

Man on Diving Board Study is shown below.

Using small beads (like sand), the surface will be blasted to remove any dirt or oil.

Read the full excerpt from our book HERE.

See the finished work featured in this post by clicking below. The final step, Patina, will be revealed next time.

Part 1:  Sculpting

Part 2:  Molding

Once the molds have been delivered to the foundry, the process begins in the wax room. Here, the molds are painted with wax, building up a thickness of 1/4″ – 3/8″ thick. The wax is removed from the mold, creating a wax duplicate of the original sculpture. To recap, we had the original sculpture (a positive), the rubber and plaster mold (a negative), now the wax is another positive. Wax sprues or channels are added to aide in casting so that the bronze will flow smoothly and will be removed once cast (shown in bright red wax below).


Various tools are used to attach the wax sprues to the wax figure.


Next stop, the ceramic room. The assemblage is dipped in a liquid ceramic slurry.

Sand is poured over the assemblage, starting with a very fine sand, picking up all of the super fine details.

The repetition of ceramic slurry coated in sand is repeated 10-14 times, building a ceramic shell around the wax piece, allowing it to dry between each coat. Below, wax pieces encased in ceramic are shown in various stages of ceramic shell. As the coats increase, the coarseness of the sand also increases. The ceramic shell is our next “negative” in the casting process. We went from positive (original sculpture), negative (rubber and plaster mold), positive (wax cast) and now negative with the ceramic mold.

The ceramic mold is a one-time use mold. For each casting in the edition, we’ll start back in the wax room with the artist’s rubber and plaster mold. Next it will be on to the foundry to heat it up, literally.

Let’s start at the beginning (briefly). Bronze has been the metal of choice by artists for centuries for its casting and color capabilities. Originating in Asia and The Mediterranean thousands of years ago, the bronze casting process varies little from the process used in ancient times. A few facts: Bronze is made up of 95% copper with silicon, manganese and tin making up the remaining 5%. It will never rust and endures the passage of time well.

Before we get to bronze casting, our story starts in the studio where the artist puts the finishing touches and marks on an original sculpture. The original itself may be made from a variety of materials: clay, wax or plaster. Texture plays a key role in the artist choosing which material or combination of materials will be used.

In the example of Woman at the Center, Tom Corbin’s newest sculptural accessory, he’s chosen wax. The sculpture itself is complete and now we want to create a mold so that multiple castings may be made. Each casting is an “edition” in the series and all Corbin sculptures are limited editions with the exception of a few miniatures.

The first step in creating a mold is to consider how the piece will be cast at the foundry and plan accordingly to obtain a successful casting. In order for the foundry to use a mold, they need to be able to open it up, requiring a two-part mold (a top and bottom or two sides depending on how you look at it). In this case, a bed of clay is used to partition the sculpture. Shown in bright red wax, sprues (or channels) are added to the mold. The sprues will ensure that bronze flows smoothly to the figure at the center.

Registration marks are engraved in the surrounding clay bed so that both parts of the mold will register perfectly.

Multiple coats of silicone rubber are painted on the assemblage, picking up each and every detail in the original sculpture, including the finest of details like fingerprints.

Registration tabs (shown below in light lavender) are added ~ this time to make sure the rubber mold will register with the plaster “mother mold” (the next step)…

While the rubber mold retains all of the detail in the original sculpture, it does not have the structure to hold the shape or form. Plaster is applied to create a rigid “mother mold”. This will keep the positions of elements such as arms and legs in proper form.

The clay bed is removed so that the other side can be molded. A release agent has been sprayed so that the two halves may be separated later on. Below, Tom paints the first layer of rubber on the opposite side of the two-part mold.  The plaster process is now repeated on the second side, which completes the mold.

The original sculpture is removed from the rubber and plaster mold. Occasionally, Tom will keep the original sculpture in wax or clay to display in the studio, but most often the materials are reused for a future sculpture. The finished mold is now delivered to the foundry where they will begin the casting process.

A sculpture will begin by any number of planned or chance circumstances. Sometimes it’s an inspiration from a trip or a photograph or nature or perhaps an idea that has intrigued the artist for years. Something they just can’t not create. The steps generally have a common thread ~ sketches and drawings focus the idea, a maquette (or study) is made, then a drawing to scale for proportions, then on to the sculpture where an armature (or framework) is constructed. But this is just a guideline, it could be that drawing upon drawing never takes on three-dimensional form. Or sometimes the artist will go straight to a full scale sculpture, throwing planning and caution aside, to express an idea.

Wire tools, carving tools, brushes and most importantly hands and fingers will be used to add clay, carve, scrape, coerse, model, shape and form the sculpted piece.

Below, an armature is made using a wooden base and plumbing pipe that is attached to the figure. Wire is shaped creating the rough form, which is covered in an oil based clay that will not dry or harden.

Rough marks are shown on the surface of the clay, using mostly fingers to shape the form.

Details begin to emerge including facial expression and clothing elements.

Below, more details, modifications on her dress (now strapless), refinements to her face and the addition of the sunflower in her hands.

More refinements, especially in the texture or sculptor’s marks that are applied to the entire surface. The bronze base is refined and squared off. A new sunflower is added, this time in wax to obtain finer detailing and structure to the delicate stem and petals.

A plumb line is hung to check the position of the body and for overall straightness in form.

The finished sculpture is photographed, documenting the sculpture from all angles before molding begins ~ which is where we’ll pick up next time.


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