GLASS AND METHOD OF INDUCING EVOLUTION OF BUBBLES

Abstract: A beer glass (10) comprises a base (12) and side wall (14). A minor part of the base (12) e.g. an annular region (16) at the junction between the base (12) and side wall (14) is treated e.g. by sand blasting. In use, pouring of a carbonated beverage of a relatively high carbon dioxide content (e.g. above about 1.3 - 1.5 volumes) induces the evolution of bubbles in a controlled manner in the beverage, by contact of the beverage with nucleation sites provided by the sand blasted region (16). The method tends to induce evolution of bubbles in a controlled manner in the beverage.

Description: GLASS AND METHOD OF INDUCING EVOLUTION OF BUBBLES This invention relates to a glass suitable for use in vending a carbonated beverage and to a method of inducing the evolution of bubbles in a carbonated beverage. The evolution of bubbles from a carbonated beverage, for example beer, soft drinks, or other carbonated beverages, as the beverage stands in the glass is attractive to the consumer and, in the case of beer and other like beverages, helps promote the quality of the foam or "head" on the glass. Bubble formation in the glass is dependent on the presence of nucleation sites on the surface of the glass: bubbles will not form if nucleation sites are not present or if the sites are filled with liquid. Thus if beer is dispensed into a wet glass (either prewetted with beer, or wet after water washing) nucleation may be impaired. One of the various objects of the invention is to provide an improved glass suitable for use in vending a carbonated beverage. Another of the objects of the present invention is to provide the improved method of inducing the evolution of bubbles in a carbonated beverage. In one aspect the invention may be considered to provide a glass suitable for use in vending a carbonated beverage wherein the interior of the glass is treated to provide nucleation sites on the surface of the glass whereby, in use, to stimulate evolution of bubbles in a carbonated beverage in the glass in a controlled manner. Suitably, the treated region is a minor part of the area of the interior, preferably at a lower part of the glass, more preferably on a base portion of the glass. Typically in supplying beer for consumption, the glass used may have a base portion provided by a substantially flat base of the glass and a side wall upstanding from the base around the periphery thereof. However, the invention may be applied to the base portion of glasses of other common shapes, e.g. goblet shape, if desired. Although it would be possible to appropriately treat the whole area of the base portion (even the whole glass) to produce bubbles, in a typical glass, it has been found with some treatments that not only does this tend to cause the base portion of the glass to look opaque and aesthetically unattractive but also excessive bubble formation can tend to arise. Thus, preferably the treated area is a minor part of the base portion which occupies less than 10% of the area of the base portion, for example about 5% of the area, or even less when using some etching techniques. In a preferred glass in accordance with the invention the base portion consists of a base which is circular in plan and the minor part of the base is an annular region of the base adjacent the junction of the side wall with the base of the glass, and preferably as close as possible to the side wall. A narrow ring around the base of the glass is not only difficult to see but tends to promote nucleation in such a way as to provide a very desirable appearance for bubble generation in beer. The minor part may consist, alternatively, or in addition to an annular ring, of a treated region in a central portion of the base portion of the glass, suitably in the form of a logo. A • logo provides a stream of bubbles of unusual appearance which may provide an attractive feature in some circumstances. As further alternatives the minor part may comprise a complex pattern of lines, a diffuse pattern of dots, pictures, alphabet characters, numbers, writing or combinations of these, or indeed other configurations. The treated part may be produced by any suitable method. However, certain techniques which involve scratching of the treated region, e.g. the base portion, for example with a diamond glass cutter, while providing some effect, are not acceptable on a commercial scale for a number of reasons, for example, scratches tend to grow and weaken the glass so that it is more prone to breakage and also may harbour microorganisms adversely affecting hygiene, as well as being unsightly. Preferred treatments include sand blasting or acid etching of the region to be treated which does not significantly weaken the glass and permits washing procedures which can effectively remove contaminants from the treated region. The treatment is effected to provide the degree of roughness necessary to provide a desired amount of nucleation in the beverage intended to be supplied in the treated glass. In another aspect the invention may be considered to provide a method of inducing the evolution of bubbles in a controlled manner in a carbonated beverage of relatively high carbon dioxide content comprising procuring a glass wherein the interior of the glass is treated to provide nucleation sites on the surface of the glass and introducing the carbonated beverage into the glass. In carrying out a method as set out in the last preceding paragraph, use is preferably made of a glass in accordance with the invention. Preferably the carbon dioxide content of the beverage is in excess of 1.3 volumes. The term "volumes" where used herein with reference to gas content of a beverage is intended to denote the volume at Standard Temperature and Pressure (S.T.P.) of the gas referred to which is dissolved in unit volume of the beverage. Whereas a method in accordance with the invention is especially applicable to beverages in which substantially all of the dissolved gas is carbon dioxide, the method may also be applicable to beverages also including other suitable gases, for example nitrogen. A method in accordance with the invention may be used in many glasses commonly used in dispensing carbonated beverages, for example beer glasses, which typically are of half pint (about 0.28 litres) or one pint (about 0.57 litres) capacity. There now follows a detailed description, to be read with reference to the accompanying drawing, of a glass embodying the invention. It will be understood that this glass has been selected for description to illustrate the invention by way of example. In the accompanying drawing:- Figure 1 is a plan view of a glass embodying the invention. The illustrative glass (10) comprises a base (12) and an upstanding side wall (14) . The base (12) is circular in plan and an annular region (16) of the base, adjacent the junction of the side wall (14) with the base (12) , is treated by sand blasting or by LASER etching to produce a slightly roughened surface. The annular region (16) occupies about 5% of the area of the base when etched by sand blasting, or perhaps as little as 0.5% of the area of the base when etched using a LASER. Where the region (16) is treated by sand- blasting, the sand-blasted region which promotes the best nucleation of gas bubbles has irregular surface pits with the following properties. The pits comprise approximately 49% (49 ± 11%) of the glass surface of the region with an average pit area of approximately 30 μm 2 (maximum 50 xm 2 ) and an average pit depth of 8 μm (maximum 20 μm) . Sand blasting can also give rise to areas which do not support good nucleation of gas bubbles and these have been found to possess irregular surface pits with the following properties. The pits comprise approximately 23% (23 ± 10%) of the glass surface with an average pit area of 5 μ 2 (maximum 50 μm 2 ) and an average pit depth of 2 μm (maximum 5 μm) . The glass surface may be treated as a manual operation using a Guyson Manual Sand-Blast Cabinet fitted with tungsten wear parts. The sand is directed into the base (12) of the glass through the aperture created between two concentric hollow cones of slightly different size. The operation is carried out with a glass inverted, and with the base of the cone inserted into the glass close to the base, such that when the sand-blast is actuated the sand particles are jetted upwards into the glass and etch a ring as they leave the hollow conical guide. The width of the ring etched by this apparatus may be varied by moving the inner cone relative to the outer. During treatment the glass surface is exposed to sand (Alumina S of mesh size 120/220, i.e. all of the sand passes through a sieve of 120 meshes per inch but the sand is retained on a sieve having 220 meshes per inch) for between 0.8 and 1.2 seconds. The motive force for the sand is supplied by compressed air at a pressure of 379-414 kN/m 2 and a flow rate of 0.34 m .min " '. It is estimated that approximately 55% of the volume of material entering the glass during the sand-blasting operation is occupied by sand particles. Where the region (16) is subjected to LASER treatment, a LASER treatment which provides good nucleation of gas bubbles two consecutive passes of the LASER beam over the same region of the glass surface. This treatment gives rise to a treated path of 281 μm in width which consists of a mixture of fine surface cracks and occasional small surface pits of approximately 10 μm diameter by 2 μm deep. A lesser degree of nucleation of gas bubbles is potentiated by a single pass of the LASER beam over the glass surface. This gives rise to a treated path of 239 μm in width in which the surface consists only of fine cracks without any pitting. Correspondingly, an excessive amount of nucleation of gas bubbles is promoted by a treatment in which the glass surface receives five consecutive treatments over the same region of the glass surface. This treatment gives rise to a treated path of 295 μm in width in which there is extensive disruption of the glass surface including surface cracking, extensive blistering and pitting of the glass surface, and occasional removal of the surface layer of glass. The LASER system used is a Shanning Sealed Tube CO- LASER (LASER QUILL) with close loop refrigeration and which is controlled using a PC-based graphics package. The power output of the LASER is variable up to 50 W, and a suitable glass treatment has been found to consist of the following. The LASER is used to etch one or more closely spaced concentric rings in the base of the glass, all the rings receive two separate LASER passes (each taking 217 S to execute) . The treated path within the rings has a breadth of approximately 281 μm. A suitable LASER power used for producing this treatment is 40 W. The LASER beam width is about 300 μm. The LASER wavelength is 10.6 μm. Similar systems to those described above can be used to treat regions having other configurations than the annular ring (16) In use in carrying out a method in accordance with the invention, a carbonated beverage of a relatively high carbon dioxide content (in excess of 1.3 volumes e.g. 1.3 - 1.5 volumes) is poured into the glass. The annular region (16) provides nucleation sites on the base of the glass which cause the generation of bubbles of a desirable appearance in beer. By suitably selecting the area and coarseness of treatment of the annular region (16) , controlled and consistent nucleation of the carbonated beverage is provided, giving a relatively consistent appearance to the beverage when dispensed for supply to a consumer. In commonly available glasses for supplying beer to a consumer, the nucleation is variable depending on washing procedures, glass age and the like, and thus the bubble generation and appearance of the beverage is unpredictable. The nucleation in carrying out a method embodying the invention in fact tends to accelerate the rate of gas loss from beer (although generating bubbles more uniformly than standard beer glasses) ; however the rate of gas generation is unlikely to cause any adverse effect to the taste of the beer, provided that the beer is consumed within about 30 minutes of dispensing into the glass.

Claims: CLAIMS 1. A glass suitable for use in vending a carbonated beverage wherein the interior of the glass is treated to provide nucleation sites on the surface of the glass whereby, in use, to stimulate evolution of bubbles in a carbonated beverage in the glass. 2. A glass according to Claim 1 wherein the treated region of the glass is a minor part of the area of a base portion of the glass. 3. A glass according to Claim 2 wherein the minor part occupies less than 10% of the area of a base portion of the glass. 4. A glass according to Claim 3 wherein the minor part occupies about 5% of the area of the base portion. 5. A glass according to Claim 3 wherein the minor part occupies about 0.5% of the area of the base portion. 6. A glass according to any one of Claims 2 to 5 wherein the base portion comprises a base which is circular in plan, the glass comprising a side wall upstanding from the base and wherein the minor part is an annular region of the base adjacent the junction of the side walls with the base. 7. A glass according to any one of the preceding claims wherein the treated part includes a region in a central portion of a base portion of the glass. 8. A glass according to any one of the preceding claims wherein the treated part is produced by sand-blasting. 9. A glass according to any one of Claims 1 to 7 wherein the treated part is produced by etching. 10. A glass substantially as hereinbefore described with reference to the accompanying drawings. 11. A method of inducing the evolution of bubbles in a carbonated beverage of relatively high carbon dioxide content comprising procuring a glass wherein the interior of the glass is treated to provide nucleation sites on the surface of the glass and introducing the carbonated beverage into the glass. 12. A method according to Claim 9 wherein the carbon dioxide content of the beverage is in excess of 1.3 volumes. 13. A method according to either one of Claims 9 and 10 wherein there is used a glass according to any one of Claims 1 to 8. 14. A method of making a glass according to any one of Claims l to 9 comprising procuring a glass, and treating a region of the interior of the glass to provide nucleation sites on the surface of the glass. 15. A method according to Claim 14 wherein the region is treated by sand-blasting. 16. A method according to Claim 14 wherein the region is treated by LASER etching.

Inventors: CROMPTON IAN EDWARD, HEGARTY PAUL KEVIN, CROMPTON, IAN, EDWARD, HEGARTY, PAUL, KEVIN
Applicants: BASS PLC
Application year: 1992
Main classification: A47G19
IPC codes: A47G19