A screw cap or Closure is a common type closure for bottles, jars, and tubes.

Usage
A screw closure is a mechanical device which is screwed on and off of a "finish" on a container. Either continuous threads or lugs are used. It must be engineered to be cost-effective, to provide an effective seal (and barrier), to be compatible with the contents, to be easily opened by the consumer,often to be reclosable, and to

comply with product,package, and environmental laws and regulations. Some closures need to be tamper resistant and have child-resistant packaging features.

Wine Industry

Its use as an alternative wine closure is gaining increasing support as an alternative to cork for sealing wine bottles. A screw cap is a metal cap that screws onto threads on the neck of a bottle, generally with a metal skirt down the neck to resemble the traditional wine capsule ("foil"). A layer of plastic (often PVDC), cork, rubber, or other soft material is used as wad to make a seal with the mouth of the bottle.

Benefits and concerns

In brief, compared to cork:

screw caps prevent the wine faults of oxidation and of cork taint, and are easier to open; there are concerns about long-term aging (aging for decades).

cork is traditional, viewed by customers as higher-end, and has a proven track record.

Traditionally associated in the US with extremely inexpensive jug wines or even "skid row" wines, the screwcap is making a comeback due to concern about premature (or sporadic) oxidation and cork taint. Screwcaps have a much lower failure rate than cork, and in theory will allow a wine to reach the customer in perfect condition, with a minimum of bottle variation. Cork, of course, has a centuries-old tradition behind it, and there are also concerns about the impact of screwcaps on the aging of those few wines that require decades to be at their best. Some argue that the slow ingress of oxygen plays a vital role in aging a wine, while others argue that this amount is almost zero in a sound cork and that any admitted oxygen is harmful. Various studies are underway, although one data point is that producers in Champagne have aged their wines under crown cap for quite some time with no apparent outcry. Even though most wine is consumed within a year of production, it may be advantageous to use screwcaps due to the relatively high incidence of cork taint.

Stelvin screw caps

The most known brand of wine screw caps is Stelvin, a brand of Rio Tinto Alcan. The brand is so common that it is genericized in common use, with many in the wine trade referring to screw caps as "Stelvin closures", regardless of brand.

The distinguishing features of wine screw caps, in particular Stelvin brand ones, are: a long outside skirt, for aesthetics: to resemble the traditional wine capsule

("foil") the use of the plastic PVDC (Polyvinylidene chloride) as a neutral liner on the inside wadding.

History

The Stelvin was developed in the late 1960s and early 1970s, and commercialized in the 1970s.It was developed by French company La Bouchage Mecanique, thence acquired by Pea-Pechiney, which became part of Alcan, now Rio Tinto Alcan. It was developed at the 1964 behest of Peter Wall, Production Director of the Australian Yalumba winery, working with other companies. It was preceded as a closure by a Stelcap/cork combination (closed with cork, with a Stelcap on top): the Stelcap was also a long-skirted screw cap, but with a different inner lining (paper over cork, instead of tin covered by PVDC in a Stelvin).

It was originally trialled in 1970/71 with the Swiss wine Chasselas, which was particularly affected by cork taint, and first used commercially in 1972 for the Swiss winery Hammel. It was adopted commercially in Australia in late 1976/early 1977. For noble wines, wines from the 1971/72 vintage (such as Haut-Brion) were sealed with Stelvin, then tasted in 1978, and found similar to cork-closed wines.

Adoption

Screw caps met with customer resistance in Australia and New Zealand, and were phased out in the early 1980s, only to be reintroduced gradually in the 1990s. They were widely adopted in the 1980s by Swiss winemakers, and have shown increasingly wide adoption in the succeeding years.

In New Zealand, adoption went from 1% in 2001 to 70% in 2004.

Screw cap adoption in fine wines is proceeding in fits and starts. In July 2000, a group of producers of Clare Valley Rieslings bottled a portion of their wines in screwcap, and earlier that year PlumpJack Winery announced it would bottle half its production of US$130 1997 Reserve Cabernet Sauvignon in screwcap. Other announcements have followed, including one from Bonny Doon Vineyard in July 2002 that 80,000 cases of its "Big House" red and white wine would be bottled under screwcaps - followed by almost all the rest of their production by late 2004 (200,000 cases total). Domaine Laroche in Chablis, France has been bottling their Chablis, Premier crus and Grand Crus on Screwcap since 2001 vintage. In July 2004 Corbett Canyon became the first million plus case brand to switch to screwcaps for their entire production, shipping just over three million cases a year. Other notable producers that have switched to screwcaps are R.H. Phillips in 2004 (300,000 cases), Hogue Cellars in 2004 (500,000 cases), and Villa Maria, also in 2004 (200,000 cases).

Sake industry

Sake bottles are almost universally closed with screw caps (some are packed in barrels, or novelty bottles).