Topic: Mdina goblet vase.

[Lustrousstone]

There's only clear glass, any colour is from the silver chloride crizzling (and the poor photo)

[chopin-liszt]

I know, but it still resulted in a coloured background. That makes it a bit on the unique side.
Like the cocktail jug Patrick now has, all the colour comes from silver chloride - even the blues are from the silver getting into the metal of the glass, but they go green because of the yellow also produced when it reacts with the glass.

[Patrick]

Vicente Boffo probably introduced this trailing having used this surface decoration at Whitefriars before he left in 1970.

http://www.glassassociation.org.uk/sites/default/files/Peter%20Wheeler%20S4.jpg

[glassobsessed]

Possibly random trailing left proud of the surface but Harris was already experimenting with trailed decoration.