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Copper, Brass, and Bronze Surfaces ZAHNER’S ARCHITECTURAL METALS SERIES Zahner’s Architectural Metals Series offers in-depth coverage of metals used in architecture and art today. Metals in architecture are selected for their durability, strength, and resistance to weather. The metals covered in this series are used extensively in the built environments that make up our world and also attract and fascinate the artist. These heavily illustrated guides offer comprehensive coverage of how each metal is used in creating surfaces for building exteriors, interiors, and art sculpture. The series provides architects, metal fabricators and developers, design professionals, and students of architecture and design with a logical framework for the selection and use of metal building and design materials. Forthcoming books in Zahner’s Architectural Metals Series will cover steel and zinc surfaces. Titles in Zahner’s Architectural Metals Series include: Stainless Steel Surfaces: A Guide to Alloys, Finishes, Fabrication, and Maintenance in Architecture and Art Aluminum Surfaces: A Guide to Alloys, Finishes, Fabrication, and Maintenance in Architecture and Art Copper, Brass, and Bronze Surfaces: A Guide to Alloys, Finishes, Fabrication, and Maintenance in Architecture and Art Copper, Brass, and Bronze Surfaces A Guide to Alloys, Finishes, Fabrication, and Maintenance in Architecture and Art L. William Zahner Cover image: © wepix / Getty Images Cover design: Wiley This book is printed on acid-free paper. Copyright © 2020 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. 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Some material included with standard print versions of this book may not be included in e-books or in print-on-demand. If this book refers to media such as a CD or DVD that is not included in the version you purchased, you may download this material at http://booksupport.wiley.com. For more information about Wiley products, visit www.wiley.com. Library of Congress Cataloging-in-Publication Data: Names: Zahner, L. William, author. Title: Copper, brass, and bronze surfaces : a guide to alloys, finishes, fabrication, and maintenance in architecture and art / L. William Zahner. Description: Hoboken, New Jersey : Wiley, 2020. | Series: Zahner’s architectural metals series | Includes bibliographical references and index. Identifiers: LCCN 2019045098 (print) | LCCN 2019045099 (ebook) | ISBN 9781119541660 (paperback) | ISBN 9781119541677 (adobe pdf) | ISBN 9781119541684 (epub) Subjects: LCSH: Copper. | Brass. | Bronze. | Architectural metal—work. | Art metal—work. Classification: LCC TS620 .Z34 2020 (print) | LCC TS620 (ebook) |DDC 739—dc23 LC record available at https://lccn.loc.gov/2019045098 LC ebook record available at https://lccn.loc.gov/2019045099 Printed in the United States of America 10987654321 This book is in honor of Salvatore Orlando. He was a good friend and advocate of the red metal. Contents Preface xi CHAPTER 1 Introduction—Element 29 1 Introduction 1 Color 6 Colors of Alloys 8 Copper Minerals 12 History 13 The Modern Copper Production Process 19 Sustainability, Environmental, and Hygienic Concerns 22 Copper and Water 23 Health and Safety 24 Copper: The Antimicrobial Metal 25 Copper Alloys for the Arts 26 CHAPTER 2 Copper and Its Alloys 31 Introduction 31 The Rich History of Copper Alloys 31 Elements Added to Copper 33 Alloy Designation System 34 The Unified Numbering System 34 Tempers 36 Wrought Copper Alloys 38 Brasses 40 Leaded Brasses 49 Tin Brasses 54 Phosphor–Bronze Alloys 56 Aluminum–Bronze Alloys 58 Silicon–Bronze Alloys 60 Copper–Nickel and Nickel–Silver Alloys 61 Cast Alloys 66 Red Brasses 69 Yellow Brasses 71 Silicon–Bronze Alloys 73 vii viii Contents A Tin–Bronze Alloy 76 Nickel–Silver Alloys 77 A Manganese–Bronze Alloy 78 CHAPTER 3 Surface Finishes 79 Introduction 79 Mill Surfaces 80 Mechanical Finishes and Temporary Protection 81 Color from Oxidation and Chemical Reactions 91 Textures 123 Tin-Coated Copper 135 Melted Copper Alloy Surfacing 136 Copper and Glass 137 Protecting the Surface 138 CHAPTER 4 Expectations of the Visual Surface 139 Introduction 139 Intent: An Unchanged Surface Appearance 143 Intent: A Surface Appearance That Changes Naturally 154 Flatness 155 Texturing the Surface 160 Initial Oxidation on Copper Alloys 161 In Situ Patination 163 Prepatination 164 The Effect of Sealants 166 The Cast Surface 167 Arriving at the Best Possible Outcome 167 CHAPTER 5 Designing with the Available Forms 173 A Brief History 173 Wrought Forms 176 The Cast Form 204 CHAPTER 6 Fabrication Processes and Techniques 211 Introduction 211 Forming 213 V-cutting 215 Cutting Copper Alloys 220 Machining 227 Soldering, Brazing, and Welding 231 Casting 241 Contents ix CHAPTER 7 Corrosion Characteristics 251 General Information 251 Categories of Corrosion 260 Environmental Exposures 279 Acids and Bases 283 Copper Alloy Surface Categories 286 CHAPTER 8 Maintaining the Copper Alloy Surface 295 Introduction 295 Protecting the New Copper Alloy Surface 296 Achieving Physical Cleanliness 296 Achieving Chemical Cleanliness 311 Achieving Mechanical Cleanliness 320 Repairing Patinas 326 Protecting the Surfaces of Copper and Copper Alloys 328 Cleaning the Copper Surface 333 Removing Copper Stains from Other Substances 334 Deteriorating Patinas 335 APPENDIX A Comparative Attributes of Metals Used in Art and Architecture 337 APPENDIX B Hardware Finish Codes and Descriptions 341 APPENDIX C Numbering Systems Used for Copper Alloys 345 Further Reading 347 Index 349 Preface The passage of time is reflected in the color of copper. Of all the metals used in art and architecture, copper is the most engaging. Throughout history, mankind has had a special relationship with copper. Copper has a weight and feeling of substance. It can be shaped and formed into useful objects, and more importantly, it has an appearance as natural as the colors of an oak forest in the fall: a color that shows value and the passage of time. Power and force are needed to shape the other metals used in art and architecture. Copper, on the other hand, shapes and moves under the blows of handheld chasing tools. It can be easily folded, curved, stretched, and embossed. One gets close to the metal when working with copper. Throughout human time copper and copper alloys have played different and expanding roles. Bronze sculptures of ancient deities and heroes have outlived their civilizations, even while rest- ing under the sea for thousands of years. Copper has been mined by every major civilization and converted and cast into both useful tools and decorative statues. The maritime world embraced copper alloys, particularly brass. Alloys with names such as Admiralty Bronze and Naval Brass recall a time when this metal served as biocladding on the under- side of a ship and ornamentation on the top. Consider that the military term “brass” relates to someone of high rank: the one with the brass metals or the brass-adorned hat. Copper alloys, both those with new, untarnished surfaces and those with colorful patinas, offer the artist and the designer an amazing palette of color to choose from and design with. Oxide colors will be predictable to a point, but beyond that it is nature that will take over the design. These colors will also act as potent inhibitors of corrosion. But note that both natural, untarnished surfaces and beautiful patinas on art and architecture forms will require something additional—either in the form of a coating or in the form of energy applied from an elbow—to keep them looking good. I have worked with copper and many of its alloys for decades. I have hammered it, cut it, welded it, and shaped it into beautiful pieces of art. I have experimented with creating color on the surface of the metal with chemical interaction, heat, and selective electroplating. I have worked with friends to cast it and I have formed its sheets to create incredible surfaces. Copper is special for its amazing ability to be shaped and stretched and for its ability to react with other elements and compounds to achieve a unique and beautiful surface. Copper can be cast into glass, and the glass accepts it. It can be severely shaped, and it yields to take the new shape. It can withstand the attack of powerful acids and bases, all the while forming a natural mineral surface that slows further reaction while giving a beautiful patina.