Ullage is a winemaking term that has several meanings but most commonly refers to the headspace of air between wine

Wine

Wine is an alcoholic beverage, made of fermented fruit juice, usually from grapes. The natural chemical balance of grapes lets them ferment without the addition of sugars, acids, enzymes, or other nutrients. Grape wine is produced by fermenting crushed grapes using various types of yeast. Yeast...

 and the top of the container that it is in. It can also refer to the process of evaporation

Evaporation

Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

 that creates the headspace itself or it can be used as a past tense

Past tense

The past tense is a grammatical tense that places an action or situation in the past of the current moment , or prior to some specified time that may be in the speaker's past, present, or future...

 verb

Verb

A verb, from the Latin verbum meaning word, is a word that in syntax conveys an action , or a state of being . In the usual description of English, the basic form, with or without the particle to, is the infinitive...

 to describe a wine barrel or bottle that has gone through the evaporation process (to be ullaged, etc.). The headspace of air is a mixture mostly of alcohol

Alcohol

In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....

 and water vapor

Water vapor

Water vapor or water vapour , also aqueous vapor, is the gas phase of water. It is one state of water within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice. Under typical atmospheric conditions, water vapor is continuously...

s with carbon dioxide

Carbon dioxide

Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...

 that is a by-product of the fermentation

Fermentation (wine)

The process of fermentation in wine turns grape juice into an alcoholic beverage. During fermentation, yeast interact with sugars in the juice to create ethanol, commonly known as ethyl alcohol, and carbon dioxide...

 process. In containers that are not completely air-tight

Hermetic seal

A hermetic seal is the quality of being airtight. In common usage, the term often implies being impervious to air or gas. When used technically, it is stated in conjunction with a specific test method and conditions of usage.-Etymology :...

 (such as an oak wine barrel or a cork

Cork (material)

Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber , which is endemic to southwest Europe and northwest Africa...

-stoppered wine bottle

Wine bottle

A wine bottle is a bottle used for holding wine, generally made of glass. Some wines are fermented in the bottle, others are bottled only after fermentation. They come in a large variety of sizes, several named for Biblical kings and other figures. The standard bottle contains 750 ml,...

), oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 can also seep into this space. While some oxygen is beneficial to the aging process of wine, excessive amounts can lead to oxidation and other various wine fault

Wine fault

A wine fault or defect is an unpleasant characteristic of a wine often resulting from poor winemaking practices or storage conditions, and leading to wine spoilage. Many of the compounds that cause wine faults are already naturally present in wine but at insufficient concentrations to adversely...

s. This is why wine in the barrels is regularly "topped up" and refilled to the top with wine in order to minimize the head space. In the bottle, the ullage or "fill level" of the wine can be an important indicator of the kind of care and storage conditions that the wine was kept in. After-market resellers and wine auction

Wine auction

A wine auction is an auction devoted to wine, sometimes in combination with other alcoholic beverages. There are two basic types of wine auctions: first hand wine auctions, where wineries sell their own wines, and second hand wine auctions, arranged by auction houses or other auctioneers to make...

 houses will often inspect the ullage levels of older vintage

Vintage

Vintage, in wine-making, is the process of picking grapes and creating the finished product . A vintage wine is one made from grapes that were all, or primarily, grown and harvested in a single specified year. In certain wines, it can denote quality, as in Port wine, where Port houses make and...

s to determine the potential quality and value of wine.

In the barrel

At the winery, the natural process of evaporation creates ullage in the barrel by causing some of the alcohol and water particles to escape as vapors

Vapors

Vapors may be:* Vapor, the gaseous state of matter* Vapors , an archaic term for certain mental and/or physical illnesses...

 - a loss sometimes referred to as the "angel's share". If the wine is in a container that is not completely air-tight, these vapor molecules (along with carbon dioxide) will diffuse out of the container through openings in the wood and around the bung

Bung

A bung is truncated cylindrical or conical closure to seal a container, such as a bottle, tube or barrel. Unlike a lid which encloses a container from the outside without displacing the inner volume, a bung is partially inserted inside the container to act as a seal...

 and be replaced with oxygen molecules. While some oxygen is beneficial in the maturation and break-down of some phenolic compounds such as tannin, excessive amounts of oxygen can interact with acetobacter

Acetobacter

Acetobacter is a genus of acetic acid bacteria characterized by the ability to convert ethanol to acetic acid in the presence of oxygen. There are several species within this genus, and there are other bacteria capable of forming acetic acid under various conditions; but all of the Acetobacter are...

 present in the wine and start the process of turning the wine into vinegar

Vinegar

Vinegar is a liquid substance consisting mainly of acetic acid and water, the acetic acid being produced through the fermentation of ethanol by acetic acid bacteria. Commercial vinegar is produced either by fast or slow fermentation processes. Slow methods generally are used with traditional...

. To prevent this possible oxidation and spoilage wineries will regularly "top up" the barrels by replacing the lost liquid with new wine.

The exact method and timing of topping up a wine barrel is determined by the individual wineries and can depend on the type of wine or grape variety that is being produced. A barrel can be topped off anywhere from once a week to every month and a half. The position of the barrel can affect the speed and degree of evaporation and the need for topping up. If the barrel is sitting with its bung hole on top, aeration

Aeration

Aeration is the process by which air is circulated through, mixed with or dissolved in a liquid or substance.-Aeration of liquids:-Methods:Aeration of liquids is achieved by:...

 and evaporation occurs more quickly. If the barrel is turned to the side in the bung over position, the bung is kept moist with the wine and aeration occurs at a slower pace. The wine that is replaced during the topping up is usually the same wine taken from another smaller container (such as a carboy

Carboy

A carboy is a rigid container with a typical capacity of 5 to 15 gallons . Carboys are primarily used for transporting fluids, often water or chemicals.They are also used for in-home fermentation of beverages, often wine.-Brewing:...

) with the barrel filled to the very top to where the reinsertion of the bung causes some spillage.

In the bottle

The ullage level of a wine bottle is sometime described as the "fill level". This describes the space between the wine and the bottom of the cork. During the bottling process, most wineries strive to have an initial ullage level of between 0.2-0.4 inches (5-10mm). As a cork is not a completely airtight sealant, some wine is lost through the process of evaporation and diffusion. As a wine ages in the bottle, the amount of ullage will continue to increase unless a wine is opened, topped up and recorked. If the wine is stored on its side, in contact with the cork, some wine will also be lost by absorption into the cork with longer corks having the potential to absorb more wine (and thus create more ullage) than shorter corks.

Generally the greater the amount of ullage, the more potential that the wine has been exposed to harmful levels of oxidation. This is why auction houses and retailer of mature wines pay close attention to the ullage levels in determining the resale value of the wine. The ullage level can also give insight as to the type of care and storage condition that the wine was kept in. Wines that have been kept at ambient humidity

Humidity

Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...

 levels and in temperatures between 50-59°F (10-15°C) will experience evaporation and diffusion at a slower rate than wine kept in lesser conditions and will thus have a lower ullage levels. In certain wines, such as Bordeauxs, ullage levels can be of a greater concerns than other wines, such as Ports, Sauternes

Sauternes (wine)

Sauternes is a French sweet wine from the Sauternais region of the Graves section in Bordeaux. Sauternes is made from Sémillon, Sauvignon Blanc, and Muscadelle grapes that have been affected by Botrytis cinerea, also known as noble rot. This causes the grapes to become partially raisined,...

 and very tannic Barolo

Barolo

Barolo is a red Denominazione di Origine Controllata e Garantita wine produced in the northern Italian region of Piedmont. It is made from the Nebbiolo grape and is often described as one of Italy's greatest wines...

s since some oxidation can be beneficial to the wine.

There are standard descriptions used by wine merchants and auction houses for the fill levels (ullage levels) of wine. The fill levels descriptions are different for Bordeaux and Burgundy wines due to the different shape of the bottles from those two regions.

Broadbent's ullage guide

In the late 1980s, Master of Wine

Master of Wine

Master of Wine is a qualification issued by The Institute of Masters of Wine in the United Kingdom...

 and senior consultant of Christie's

Christie's

Christie's is an art business and a fine arts auction house.- History :The official company literature states that founder James Christie conducted the first sale in London, England, on 5 December 1766, and the earliest auction catalogue the company retains is from December 1766...

 auction Michael Broadbent

Michael Broadbent

John Michael Broadbent MW is a British wine critic, writer and auctioneer in a capacity as a Master of Wine...

 developed a guide for evaluating the ullage levels of matured wines. While the focus of his guide was primarily on Bordeaux, it has been generally accepted and widely used in the wine market as an evaluation tool for all sorts of wine. The terms are used to describe the levels of wine in a wine bottle. They are commonly used to describe old wine bottles offered for sale in wine auction

Wine auction

A wine auction is an auction devoted to wine, sometimes in combination with other alcoholic beverages. There are two basic types of wine auctions: first hand wine auctions, where wineries sell their own wines, and second hand wine auctions, arranged by auction houses or other auctioneers to make...

s and by dealers in rare wine. Despite the guide's popularity, Broadbent has been quoted as regretting his decision not to copyright

Copyright

Copyright is a legal concept, enacted by most governments, giving the creator of an original work exclusive rights to it, usually for a limited time...

it.

Ullage level (in/cm)	Appearance	Assessment
0.12 in (0.3 cm)	High up to the cork	Normal level for young wines
0.2 in (0.5 cm)	High in neck	Good condition for any age
0.6 in (1.5 cm)	Top of the shoulders	Normal for older wines. Good condition for wines over 15 years
1 in (2.5 cm)	Upper part of shoulders	Generally okay in older wines, especially those over 20 years
1.18-1.38 in (3-3.5 cm)	Mid to mid-low shoulders	Possible oxidation. Price should reflect the risk.
2.36-2.75 in (6–7 cm)	Low shoulders to below shoulders	Extremely risky. Possibly undrinkable