Wine Press Body

introduction

Winemaking is about capturing the elements. The subtlety of the fruit, the soul of the place, the passage of the seasons, the passion of the maker.

Bottling is about preserving these elements. Maintaining them throughout the life of the wine, and at the same time allowing them to develop and mature appropriately. In this process, the seal of the bottle is vital.

While the closure in itself may appear to be of little consequence, its significance is profound, for in it lies the ability to preserve — or to diminish — the very subtlety, soul and passion of the wine. It is the closure’s responsibility to ensure that the wine emerging from the bottle is every bit as good as that which went into it. The pursuit of quality in this area has been the motivating factor that has led many winemakers to choose the screw cap.

This book is about quality. The quality of the wine in the bottle is the underlying theme of every chapter. This is the defining principle of closure choice, and the foundation on which every aspect of its use is based. The pursuit of quality is a passion shared by the three contributing editors of this book, and is clearly evidenced throughout their own winemaking. Each produces wines of a premium standard, and has selected the screw cap to ensure that this standard is not compromised.

The subtlety, the soul and the passion of these three individuals are woven throughout the pages of this manual. The focus lies not on the minimum requirements for the acceptable use of screw caps, but rather on achieving the very highest standards of winemaking and bottling for premium wines.

A unique closure

Product improvement and development must be maintained as high priorities in any industry. For the wine industry, this has never been more pertinent than it is today. In the modern wine world, every producer competes on a global stage against an ever-growing number of players. The market is more competitive than in any other era. In response, winemakers and wine marketers find themselves in constant pursuit of higher standards. More appealing packaging, more deliberate marketing, more intricate vineyard management, more advanced winemaking techniques – every avenue for product improvement is employed in an attempt to create the highest quality product in the most appealing package at the most affordable price.

Within this package, the closure is unique. It may be the last important step in the winemaking process, but it is far from the least. It stands out as the one component that forms an integral part of both the appeal of the package and the quality of the wine. In recognition of this, winemakers have spent centuries experimenting with closures that endeavour to maintain both wine quality and aesthetic appeal. In recent years, we have seen all variations of chemical, enzymatic, radiation, steam and even genetic treatments for natural corks, as well as membranes around corks, composite corks, two-plus-two corks, synthetic closures, glass stoppers (such as Vintegra), plastic twist-off closures (like Zork) and numerous variations.

It is apparent that there is no such thing as a perfect universal closure, but after some thirty-five years of rigorous testing it is now acknowledged that the screw cap comes closer than any other to this ideal. Screw caps have been used commercially as wine seals since the early 1970s, and are now recognised as a reliable seal for all wine types. Many companies have accepted them as a closure for their wine products in recent years, in response to continuing problems with traditional closures. These problems relate primarily to cork taint, sporadic (random) oxidation, flavour scalping (stripping) and “corky” flavours. When used in conjunction with the right bottles and applied in the correct manner with the appropriate equipment, the screw cap provides a sound seal, offering the winemaker and the consumer a high degree of confidence in package integrity.

However, discrepancies in the bottle, the cap, the application procedure, the handling of the sealed bottle and even the chemistry of the wine itself can produce discrepancies in the quality of the seal and of the wine. Screw caps are an entirely different closure technology to corks, and as such, bring with them their own set of requirements and pitfalls for wine preparation, bottling and storage.

Screw caps are inherently different to corks in a number of ways. Screw caps form a seal with the outside of the bottle, while corks form a seal with the inside of the bottle. Screw caps are manufactured products which perform consistently. Corks are natural products, with all of the inherent variability which this entails. Screw caps provide a near-impermeable barrier. Corks facilitate, to varying degrees, the passage of gases. Screw caps require strict tolerances in capping procedures in order to produce a good seal. Corks are forgiving and will adapt to overcome some imperfections in the bottle surface. As a consequence of these differences, tolerances for screw caps are less flexible and less forgiving than those of corks. All parameters must be controlled to meet strict requirements.

These findings have come to light in recent years, as a result of the increasing use of screw caps across the wine industry. It has become apparent at the same time that a specific knowledge base is required for winemaking and bottling with screw caps, and that this knowledge is intrinsically different in many ways to that traditionally associated with bottling under cork. It is the purpose of this manual to bridge this gap.

Critical timing

The rate of uptake of screw caps in recent years has greatly exceeded that of any other development in wine closure technology in any period of wine history. Just five years ago, outside of Switzerland, there were barely a handful of screw-capped wines on the market. Today, literally hundreds of millions of bottles are sealed with the closure every year.

This growth has exceeded even the most ambitious predictions. Originating in Switzerland, Australia and New Zealand, the use of screw caps has quickly spread to France, Germany, the United States, Canada, South Africa, South America and elsewhere.

During the uptake phase for any new product, the demand for information and experience regarding best practice is at a premium. The rapid growth in the use of screw caps internationally has not allowed time for adequate dissemination of this information worldwide. In Australia and New Zealand, winemakers with experience have found themselves in demand as consultants for their peers, in some cases receiving more enquiries than they are capable of handling. But outside of these countries, the expertise of such individuals is less accessible. Winemakers have had little choice but to learn “on the job,” and patch up any problems that are an inevitable consequence of this approach.

The dissemination of information relating to winemaking and bottling with screw caps has never been more crucial than during this current period of rapid escalation in their use worldwide.

The international debate has quickly evolved from the question of “Should we use screw caps?” through “Why should we use screw caps?” to now “How can we best use screw caps?” In the minds of many consumers, the first two questions remain, and as such the industry should uphold them as priorities as it seeks to promote the closure. But the key question that remains prominent is that of providing the expertise that enables every producer in every country to maintain best practice in the use of screw caps. It is to this question that this book is addressed.

In recent years, the media has been quick to highlight problems associated with screw-capped wines. Leaking closures, bottle imperfections, reductive sulphide characters, oxidation, bacteriological contamination and volatile acidity faults have all featured in the wine news. It seems that almost every winery venturing into screw caps has developed its own set of procedures and guidelines. In doing so, mistakes have inevitably been made and lessons have been learnt. More recently, however, winemakers have developed strategies for largely avoiding these problems. While this pioneering process will necessarily continue, a large body of information has already been amassed from the many wineries currently bottling premium wines with screw cap seals. This manual pulls together the expertise and lessons learned from scores of the most successful wineries in Australia, New Zealand and elsewhere.

Key expertise

In late 2003, I was approached by the contributing editors of this book with an invitation to author this project. I was already well familiar with the substantial contributions that these three individuals had made to the use of screw caps as wine closures.

In 2000, Australian Winemaker of the Year and International Riesling Winemaker of the Year, Jeffrey Grosset, led a team of Clare Valley winemakers in bottling their premium rieslings in screw cap. It was a brave initiative, for what were predominantly small, family wineries, to risk taking on a closure that had previously been rejected by the market. All the more so given the substantial cost of having a new bottle produced and shipped from France expressly for the purpose. The initiative was a resounding success, and Jeffrey Grosset quickly became one of Australia’s leading authorities in the use of the closure. His attention to detail in his own winemaking is second to none.

Such was Grosset’s enthusiasm for the closure that following a visit to New Zealand the very next year, a group of New Zealand winemakers immediately established the New Zealand Screw Cap Wine Seal Initiative, under the leadership of Ross Lawson. Key figures in this initiative were Michael Brajkovich MW of Kumeu River Wines, renowned for one of the New World’s most highly regarded chardonnays, and Dr John Forrest of Forrest Estate, with wide experience in all wine styles. Brajkovich served as inaugural chair of the initiative, while Forrest’s expertise in chemistry proved to be invaluable in refining winemaking practices for screw-capped wines. Both have been strong advocates for the closure, and deserve credit for the success that it has experienced in local and export markets. In just four years, the initiative has seen screw caps mushroom to account for over eighty percent of all New Zealand wines.

Grosset, Brajkovich and Forrest represent leading authorities in the field of screw caps. They were conscious that their experience, and that of their peers, should be documented in a manner that makes it accessible to winemakers across the globe. The demand for such information was further reinforced by the response to the First International Screw Cap Symposium in Blenheim, New Zealand, in November 2004. The attendance of some 250 delegates from twelve countries reiterated the need for the ongoing sharing of information and expertise. To facilitate this, the International Screw Cap Wine Seal Initiative was established. This initiative is responsible for funding the printing costs of this manual.

Internationally, experience with screw caps as wine closures extends over more than thirty-five years. We have come a long way since the string of failed trials of the early 1960s. Equipped with the proper knowledge, there is no reason why any of the mistakes of the past need be repeated again. This manual taps into the collective knowledge and skills of the most experienced winemakers, bottle manufacturers, cap suppliers, bottling companies and consultants in Australia, New Zealand and elsewhere. It presents a comprehensive overview of all of the issues related to the use of screw caps as wine closures.

Overview of contents

This book is divided into five sections, which detail all of the subjects relevant to screw caps as the wine progresses from the vine to the consumer. Each of these areas must work in synergy if a successful seal and a stable wine are to be achieved.

Section one provides an introduction to screw caps, the history of screw caps and twenty reasons for using screw caps. Wineries must consider the unique marketing opportunities that the screw cap affords, and a successful marketing campaign depends upon a sound understanding of the reasons for choosing screw caps.

Section two introduces the cap and the bottle, emphasising the crucial role that each plays in creating a good seal. The intricacies of such details as liners, thread, tolerances, redraw, quality assurance procedures and potential faults are explained in detail. Diagrams, illustrations and tables are utilised extensively. Where possible, specific manufacturer’s specifications and set-ups are outlined, and common pit-falls are detailed.

Wine preparation requirements for screw-capped wines differ slightly from those of their cork counterparts, and this is the focus of section three. All aspects of winemaking and chemistry as they relate to screw caps are discussed, with a particular emphasis on preparation of the wine for bottling, dissolved carbon dioxide and oxygen, sulphur dioxide levels and sulphide chemistry. This manual does not purport to be a comprehensive winemaking textbook, but rather sets out to supplement the general information already widely available, making it specifically relevant for use in the context of screw caps.

The bottling process itself forms a major emphasis of this book, and this is detailed in section four. Subtopics include filling, capping, bottling line checks, capping equipment and torques. There is a particular focus on sealing faults as well as specific technical information and specifications provided by the companies responsible for designing and manufacturing screw caps, bottles, capping heads and other equipment. It is important that wineries are familiar with the tolerances for these products in order to check and approve the materials both entering and leaving the bottling line.

The specific requirements for screw-capped bottles do not cease as soon as the bottle has been capped. Proper procedures for storage, handling and transportation are detailed in section five. The final chapter provides anecdotal evidence for the ability of screw caps to sustain wines in excellent condition throughout long periods of cellaring.

Finally, the appendices provide further, specific details backing up many of the areas discussed in the text. Appendix 1 outlines a sampling plan for quality assurance of incoming and outgoing products. Appendix 2 is a copy of a report into the role of oxygen in the ageing of bottled wine. Appendix 3 provides detail, diagrams and specifications relating to brand-specific caps, bottles and application equipment. Since bottle and cap designs are constantly evolving, the diagrams and data provided should be cross-checked with current manufacturers’ data sheets to ensure that specifications are current. The industry is progressing rapidly in this field, so much so that many of the finer details of the specifications quoted in this book were changed between first and second drafts. A list of recommended further reading and a comprehensive index complete the manual.


introduction Winemaking is about capturing the elements. The subtlety of the fruit, the soul of the place, the passage of the seasons, the passion of the maker. Bottling is about preserving these elements. Maintaining them throughout the life of the wine, and at the same time allowing them to develop and mature appropriately. In this process, the seal of the bottle is vital. While the closure in itself may appear to be of little consequence, its significance is profound, for in it lies the ability to preserve — or to diminish — the very subtlety, soul and passion of the wine. It is the closure’s responsibility to ensure that the wine emerging from the bottle is every bit as good as that which went into it. The pursuit of quality in this area has been the motivating factor that has led many winemakers to choose the screw cap. This book is about quality. The quality of the wine in the bottle is the underlying theme of every chapter. This is the defining principle of closure choice, and the foundation on which every aspect of its use is based. The pursuit of quality is a passion shared by the three contributing editors of this book, and is clearly evidenced throughout their own winemaking. Each produces wines of a premium standard, and has selected the screw cap to ensure that this standard is not compromised. The subtlety, the soul and the passion of these three individuals are woven throughout the pages of this manual. The focus lies not on the minimum requirements for the acceptable use of screw caps, but rather on achieving the very highest standards of winemaking and bottling for premium wines. A unique closure Product improvement and development must be maintained as high priorities in any industry. For the wine industry, this has never been more pertinent than it is today. In the modern wine world, every producer competes on a global stage against an ever-growing number of players. The market is more competitive than in any other era. In response, winemakers and wine marketers find themselves in constant pursuit of higher standards. More appealing packaging, more deliberate marketing, more intricate vineyard management, more advanced winemaking techniques – every avenue for product improvement is employed in an attempt to create the highest quality product in the most appealing package at the most affordable price. Within this package, the closure is unique. It may be the last important step in the winemaking process, but it is far from the least. It stands out as the one component that forms an integral part of both the appeal of the package and the quality of the wine. In recognition of this, winemakers have spent centuries experimenting with closures that endeavour to maintain both wine quality and aesthetic appeal. In recent years, we have seen all variations of chemical, enzymatic, radiation, steam and even genetic treatments for natural corks, as well as membranes around corks, composite corks, two-plus-two corks, synthetic closures, glass stoppers (such as Vintegra), plastic twist-off closures (like Zork) and numerous variations. It is apparent that there is no such thing as a perfect universal closure, but after some thirty-five years of rigorous testing it is now acknowledged that the screw cap comes closer than any other to this ideal. Screw caps have been used commercially as wine seals since the early 1970s, and are now recognised as a reliable seal for all wine types. Many companies have accepted them as a closure for their wine products in recent years, in response to continuing problems with traditional closures. These problems relate primarily to cork taint, sporadic (random) oxidation, flavour scalping (stripping) and “corky” flavours. When used in conjunction with the right bottles and applied in the correct manner with the appropriate equipment, the screw cap provides a sound seal, offering the winemaker and the consumer a high degree of confidence in package integrity. However, discrepancies in the bottle, the cap, the application procedure, the handling of the sealed bottle and even the chemistry of the wine itself can produce discrepancies in the quality of the seal and of the wine. Screw caps are an entirely different closure technology to corks, and as such, bring with them their own set of requirements and pitfalls for wine preparation, bottling and storage. Screw caps are inherently different to corks in a number of ways. Screw caps form a seal with the outside of the bottle, while corks form a seal with the inside of the bottle. Screw caps are manufactured products which perform consistently. Corks are natural products, with all of the inherent variability which this entails. Screw caps provide a near-impermeable barrier. Corks facilitate, to varying degrees, the passage of gases. Screw caps require strict tolerances in capping procedures in order to produce a good seal. Corks are forgiving and will adapt to overcome some imperfections in the bottle surface. As a consequence of these differences, tolerances for screw caps are less flexible and less forgiving than those of corks. All parameters must be controlled to meet strict requirements. These findings have come to light in recent years, as a result of the increasing use of screw caps across the wine industry. It has become apparent at the same time that a specific knowledge base is required for winemaking and bottling with screw caps, and that this knowledge is intrinsically different in many ways to that traditionally associated with bottling under cork. It is the purpose of this manual to bridge this gap. Critical timing The rate of uptake of screw caps in recent years has greatly exceeded that of any other development in wine closure technology in any period of wine history. Just five years ago, outside of Switzerland, there were barely a handful of screw-capped wines on the market. Today, literally hundreds of millions of bottles are sealed with the closure every year. This growth has exceeded even the most ambitious predictions. Originating in Switzerland, Australia and New Zealand, the use of screw caps has quickly spread to France, Germany, the United States, Canada, South Africa, South America and elsewhere. During the uptake phase for any new product, the demand for information and experience regarding best practice is at a premium. The rapid growth in the use of screw caps internationally has not allowed time for adequate dissemination of this information worldwide. In Australia and New Zealand, winemakers with experience have found themselves in demand as consultants for their peers, in some cases receiving more enquiries than they are capable of handling. But outside of these countries, the expertise of such individuals is less accessible. Winemakers have had little choice but to learn “on the job,” and patch up any problems that are an inevitable consequence of this approach. The dissemination of information relating to winemaking and bottling with screw caps has never been more crucial than during this current period of rapid escalation in their use worldwide. The international debate has quickly evolved from the question of “Should we use screw caps?” through “Why should we use screw caps?” to now “How can we best use screw caps?” In the minds of many consumers, the first two questions remain, and as such the industry should uphold them as priorities as it seeks to promote the closure. But the key question that remains prominent is that of providing the expertise that enables every producer in every country to maintain best practice in the use of screw caps. It is to this question that this book is addressed. In recent years, the media has been quick to highlight problems associated with screw-capped wines. Leaking closures, bottle imperfections, reductive sulphide characters, oxidation, bacteriological contamination and volatile acidity faults have all featured in the wine news. It seems that almost every winery venturing into screw caps has developed its own set of procedures and guidelines. In doing so, mistakes have inevitably been made and lessons have been learnt. More recently, however, winemakers have developed strategies for largely avoiding these problems. While this pioneering process will necessarily continue, a large body of information has already been amassed from the many wineries currently bottling premium wines with screw cap seals. This manual pulls together the expertise and lessons learned from scores of the most successful wineries in Australia, New Zealand and elsewhere. Key expertise In late 2003, I was approached by the contributing editors of this book with an invitation to author this project. I was already well familiar with the substantial contributions that these three individuals had made to the use of screw caps as wine closures. In 2000, Australian Winemaker of the Year and International Riesling Winemaker of the Year, Jeffrey Grosset, led a team of Clare Valley winemakers in bottling their premium rieslings in screw cap. It was a brave initiative, for what were predominantly small, family wineries, to risk taking on a closure that had previously been rejected by the market. All the more so given the substantial cost of having a new bottle produced and shipped from France expressly for the purpose. The initiative was a resounding success, and Jeffrey Grosset quickly became one of Australia’s leading authorities in the use of the closure. His attention to detail in his own winemaking is second to none. Such was Grosset’s enthusiasm for the closure that following a visit to New Zealand the very next year, a group of New Zealand winemakers immediately established the New Zealand Screw Cap Wine Seal Initiative, under the leadership of Ross Lawson. Key figures in this initiative were Michael Brajkovich MW of Kumeu River Wines, renowned for one of the New World’s most highly regarded chardonnays, and Dr John Forrest of Forrest Estate, with wide experience in all wine styles. Brajkovich served as inaugural chair of the initiative, while Forrest’s expertise in chemistry proved to be invaluable in refining winemaking practices for screw-capped wines. Both have been strong advocates for the closure, and deserve credit for the success that it has experienced in local and export markets. In just four years, the initiative has seen screw caps mushroom to account for over eighty percent of all New Zealand wines. Grosset, Brajkovich and Forrest represent leading authorities in the field of screw caps. They were conscious that their experience, and that of their peers, should be documented in a manner that makes it accessible to winemakers across the globe. The demand for such information was further reinforced by the response to the First International Screw Cap Symposium in Blenheim, New Zealand, in November 2004. The attendance of some 250 delegates from twelve countries reiterated the need for the ongoing sharing of information and expertise. To facilitate this, the International Screw Cap Wine Seal Initiative was established. This initiative is responsible for funding the printing costs of this manual. Internationally, experience with screw caps as wine closures extends over more than thirty-five years. We have come a long way since the string of failed trials of the early 1960s. Equipped with the proper knowledge, there is no reason why any of the mistakes of the past need be repeated again. This manual taps into the collective knowledge and skills of the most experienced winemakers, bottle manufacturers, cap suppliers, bottling companies and consultants in Australia, New Zealand and elsewhere. It presents a comprehensive overview of all of the issues related to the use of screw caps as wine closures. Overview of contents This book is divided into five sections, which detail all of the subjects relevant to screw caps as the wine progresses from the vine to the consumer. Each of these areas must work in synergy if a successful seal and a stable wine are to be achieved. Section one provides an introduction to screw caps, the history of screw caps and twenty reasons for using screw caps. Wineries must consider the unique marketing opportunities that the screw cap affords, and a successful marketing campaign depends upon a sound understanding of the reasons for choosing screw caps. Section two introduces the cap and the bottle, emphasising the crucial role that each plays in creating a good seal. The intricacies of such details as liners, thread, tolerances, redraw, quality assurance procedures and potential faults are explained in detail. Diagrams, illustrations and tables are utilised extensively. Where possible, specific manufacturer’s specifications and set-ups are outlined, and common pit-falls are detailed. Wine preparation requirements for screw-capped wines differ slightly from those of their cork counterparts, and this is the focus of section three. All aspects of winemaking and chemistry as they relate to screw caps are discussed, with a particular emphasis on preparation of the wine for bottling, dissolved carbon dioxide and oxygen, sulphur dioxide levels and sulphide chemistry. This manual does not purport to be a comprehensive winemaking textbook, but rather sets out to supplement the general information already widely available, making it specifically relevant for use in the context of screw caps. The bottling process itself forms a major emphasis of this book, and this is detailed in section four. Subtopics include filling, capping, bottling line checks, capping equipment and torques. There is a particular focus on sealing faults as well as specific technical information and specifications provided by the companies responsible for designing and manufacturing screw caps, bottles, capping heads and other equipment. It is important that wineries are familiar with the tolerances for these products in order to check and approve the materials both entering and leaving the bottling line. The specific requirements for screw-capped bottles do not cease as soon as the bottle has been capped. Proper procedures for storage, handling and transportation are detailed in section five. The final chapter provides anecdotal evidence for the ability of screw caps to sustain wines in excellent condition throughout long periods of cellaring. Finally, the appendices provide further, specific details backing up many of the areas discussed in the text. Appendix 1 outlines a sampling plan for quality assurance of incoming and outgoing products. Appendix 2 is a copy of a report into the role of oxygen in the ageing of bottled wine. Appendix 3 provides detail, diagrams and specifications relating to brand-specific caps, bottles and application equipment. Since bottle and cap designs are constantly evolving, the diagrams and data provided should be cross-checked with current manufacturers’ data sheets to ensure that specifications are current. The industry is progressing rapidly in this field, so much so that many of the finer details of the specifications quoted in this book were changed between first and second drafts. A list of recommended further reading and a comprehensive index complete the manual.

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