At about 1892 the Loetz factory developed a procedure, that was derived from Venetian glass, to produce intense iridescence glass. At that moment the grandson of Johan Loetz, Max Ritter von Spaun, is leading the factory.

At 1895 von Spaun licensed the method of metal irisation on glass. The objects his factory created where shown to the public from 1898 and obtained the great price at the Paris international art fair in 1900. This was the starting point of Loetz's great fame in glass art.

In general there are two methods of glass irisation. First there is the method of metal irisation on glass. The objects his factory created where shown to the public from 1898 and obtained the great price at the Paris international art fair in 1900. This was the starting point of Loetz's great fame in glass art.

In general there are two methods of glass irisation. First there is the method of irisation directly in the fire and second using a 'kapeloven'. Irisation directly in the fire is done by blowing the glass and at the same time exposing it to vapours of metal oxides. The hot glass mixes with the metal oxides wich gives the iridescence . When irisation by the kapeloven is used the glass gets its iridescence afterwards. A new layer is brought on and baked at the surface of the glass. This method is similar to coating with enamel.