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Shell forming


Was: Call for Shell Forming Images for Book

Hi Ray,

Um.. What exactly is ??? I have not heard of it before. 

Sorry for the delay in response—I’m in Florida, teaching a
workshop. Following is a definition of shell forming, and an excerpt
from the book. I hope it helps your understanding. Most people have
heard of spiculums, and anticlastic raising, and maybe they have
heard of synclastic forming. These are all part of shell forming, a
way of working metal and thinking about metal forming that Heikki
Seppa developed, and wrote about in a book, Form Emphasis for
Metalsmiths. Many other artists have furthered and contributed to
the development of the techniques, including Michael Good. It is our
intent that the new book will complement the first book.

Cynthia Eid

Excerpts from the book-in-progress, Shell Forming For Jewelers and
Metalsmiths: Creative Paths to Form by Betty Helen Longhi and Cynthia


A shell is a formed sheet of metal. Heikki Seppa’s definition: “The
word shell means the outer skin of any form. The shell form is never
solid. It begins as a flat shape, but through the shell-structuring
technique, it evolves into a three-dimensional object and finally
into a hollow structure; thus the name shell structure.” (From: Form
Emphasis for Metalsmiths)


Shell forming is a system of techniques for making complex
three-dimensional structures from sheet metal. Although grounded in
traditional silversmithing, it presents new ways of working with and
thinking about form. Forming is primarily done using one resilient
tool and one steel tool. When using a metal hammer one works on a
wood or plastic stake and when using a metal stake a plastic or wood
mallet is used. The resilience of the wood or plastic tool allows
the metal to be stretched gently thus rapidly creating strong but
fluid structures. The goal of this book is to open up the vast
possibilities for form that can be created through shell forming.

There are three basic types of forms that have existed in the world
since the beginning of time. The shell forming terms for these forms
are: furrow, synclast, and anticlast. Some examples of furrows are
channels, cones, and tubes. Bowls, domes and beads are synclastic
forms, while anticlastic forms include spouts, handles, and saddles.
Examine the everyday objects that are around you and you will
discover that all forms can be described as either a furrow, a
synclast, an anticlast, or a transition from one of these to the
other. Everything else is a flat plane. It is amazing to realize
that in the world of form this is all there is! So, in theory when
you know how to make these forms, you will be able to create

By using these ways of thinking about form, and these concepts and
tools, metalsmiths are able to build upon the fundamentals of
traditional techniques in new directions. For example, making a
furrow comes from tube-making techniques, but results in a very
different object when applied to an asymmetric or tapered metal
pattern. Synclastic forming is derived from the traditional process
of sinking, but shell forming explores its possibilities more fully.
The same can be said for anticlastic forming. While the techniques
are adapted from those used to make a spout, the flared edge of a
bowl, or the lip of a pitcher, new tools, such as sinusoidal stakes,
and the adaptability of these tools allow us to explore the
anticlastic process in ways that were not possible in the past. Even
more exciting are the ways anticlastic and synclastic forms can be
used together by creating transitions from one to the other to
develop more complex forms.

Through the use of new and less confining tools, techniques, and
language we can take these processes further to create unique and
unusual forms.