History of Glass Paints
The main reason why glassware companies started to use glass paints to color glassware was purely economical. The production of colored glass takes a lot of experience and special craftmanship. Producing tank colored glass is very expensive, especially colored crystal.
The non-transparent enamels and transparent paints, which were developed and used through the ages in Bohemia and Murano, were after WWII adopted as standard materials in the glassware industry. These paints were no longer used for exclusive glassware only, but they became available for normal household glassware.
The original glass paints were applicable by hand painting and new application techniques like spraying and screen printing were developed.
The use of these paints flourished but soon some major drawbacks showed up. The high firing temperature made these coatings for glass, due to rising energy costs, expensive.
Strengthening environmental rules limited the use of these paints further, since the colors originate from metal oxides.
(Some metal oxides are very bad for the environment and health.)
With the development of the Chemical Industry after WWII, a huge variety of organic colors became available and based on these organic colors new paints, also for glass, were developed.
These organic glass paints, based on resins, had an almost infinite range of colors and the glass coatings could be cured at low temperatures. The absence of metal oxides made them the environmental friendly alternative of the available coatings for glass and so a glorious future lay ahead.
The array of organic resins is still growing. Nowadays glass can be powder coated, paints can harden out under UV-light or by radiant heat, a whole glass can be covered in one or more colors by spraying and almost any logo can be put on glass either by the decal technique or by the screen printing technique.
But these organic paints encounter an acceptance problem. The final glass coating is rather thick and looks and feels like a plastic jacket.
Although the mechanical and chemical resistance of these organic glass coatings improved much lately, it are the poor plastic looks which is working against the wide acceptance of the end users.
Hybrid Glass Paints
A new type of glass coatings are hybrid glass paints. Hybrid means in this context a combination of the vast range of organic colors embedded in a mainly inorganic matrix.
These new coatings can be applied with the same decoration techniques as the organic resins. The resulting coating is a glasslike material and it forms only a thin layer. This film is at least ten times thinner than the organic, plastic, coatings!
So the result is that it looks like glass and feels like glass.
Another interesting property is that after firing (same low temperatures as the organic coatings) the coating is chemically bonded to the glass. This chemical bond gives the coating very good properties like dish wash safeness, chemical resistance to solvents like acetone and alcohol and a good scratch resistance. On top of this does the coating not contain any toxic components and is food safe.