Adequate eye protection is required and when spraying copper, either suffficient ventilation hood or respiratory masks have to be used. However, in this study the coating was merely used for decoration. T he copper coating was found to have a very good adhesion on the hot glass surface. However, it was found that the elastic properties of metallic copper differ considerably from those of glass in its working temperature. The article to be sprayed should be in as final shape as possible during the spraying process.
Any additional glass working with the article tends to break the copper coating.
It was almost impossible to benifit from this feature because it could not be predicted, how the copper coating would break. Thus by preventing Cu20 from oxidising, e.g. by coating the copper layer with hot glass, it is possible to get a red Cu20 layer instead of black CuO layer. I n this study the different oxidation forms of copper and their different colours were used as an advantage. When copper has been sprayed on hot glass, the surface of the article, that will be seen through glass after spraying, has bright metal copper colour. In practice this is possible by gathering more glass on the article, shortly after spraying the copper.