Finishers and Decorators
Finishing refers to a whole series of procedures, ranging from cold-working to multiple decoration techniques.
Cold-working: polishing, drilling, lapping, trimming…
Cold-working is a mechanical process. It can be applied to bottles or glass stoppers.For bottles, if the client deems it necessary, this will mean making the glassware items uniform, smooth and glossy in order to achieve a perfect surface finish. This could involve, for example, simply removing the traces of the mould joint resulting from the glassmaking process. But for some bottles, all of the surfaces will be polished and shined.
It could also involve performing a drilling and lapping procedure to ensure the air-tightness of the glass and stopper.
For bottle stoppers in glass or crystal, these are made using “pressed glass” techniques. They will be produced on a glass mount, sometimes referred to as a “cloche”, which will later need to be removed by cutting, trimming and polishing.
This method consists in using a chemical process to give the surface of the glass a satin finish and silky feel. The process is strictly regulated and monitored closely, as it produces effluents that need to be treated. It’s less frequently used now than it has been in the past, and is even sometimes substituted for a lacquering process that gives a similar result.
The aim of sanding is to decorate all or part of the object to be processed, giving it a satin finish. The method involves blasting the item with an abrasive agent using compressed air, to give the surface a matte or frosted appearance. This technique therefore requires machinery to mask off the areas that are not to be frosted. These processes are carried out by other companies, but the development of affordable 3D printing leaves open the possibility of manufacturing internally in the future.
In La Glass Vallée, the decoration of bottles or carafes can call on a plethora of techniques that can be applied depending on the designers’ creative decisions, such as lacquering,screen printing, pad printing, hot marking, metallisation, chromography, sublimation, attachment of accessories or heat polishing to name just a few…
For several years, the technique of colouring glass throughout the mass, which is now primarily used in semi-automated production, has been replaced by the colouring of bottles by lacquering, also known as spraying.
This automated process is referred to as a lacquering line, makes it possible to obtain a large variety of uniform, gradient or multiple tones, coloured or uncoloured frosted finishes, or even to vary the opaqueness or feel of the bottle, and to imitate other materials (concrete, slate, etc.). Thanks to the tooling used, it is also possible to apply partial lacquers.
This technology has evolved considerably over the last decade, including in environmental terms, by replacing, in most cases, solvent inks with water-soluble inks. The lacquering process calls on a wealth of expertise in order to meet clients’ expectations: colourists, setters and operators must effectively ensure a production that is perfectly homogenous, with a few exceptions when an element of randomness can be requested.
Rigorous tests are carried out to test how well the lacquer holds when subjected to chemical or mechanical abrasions in order to ensure the longevity of the decoration. These texts are also applied to the other forms of decoration involving transfer.
Although it may seem like a form of lacquering, metallisation involves very different processes and products that require considerable investment. It’s also a process that requires glasswork products with no surface defects from the outset, as these become even more obvious when coated with a uniform black lacquer, for example.
Screen printing, pad printing, hot marking, transfer printing, sublimation, digital printing, etc…
These different types of marking make it possible to print, by transfer, any format of text or artwork on the bottles.
Screen printing consists in applying a quantity of organic ink, UV or enamel on the object via a stencil or ‘screen’: this is used for circular shapes (cylindrical or developed) and flat tracks.
Where the decoration of concave shapes is needed, a pad printing process is used to ensure that it adheres perfectly to the shapes.
The processes of transfer printing, sublimation or digital printing are used where complex polychromatic decoration is required.
Bonding – Bottle covering
The process of covering bottles with other materials has always existed in some form or another, even if simply using ribbons, but this trend has been growing for the best part of a decade. The current trend is for product sophistication, which can mean fitting accessories in metal, plastic or both, fabric or even wood to the bottles. These accessories can either be fitted with the help of automatic machines or manually.