| 摘要 |
An article made by treating the surface of a solid article made of a material having a vitreous structure, such as crystal, lead glass and the same, and containing some amounts of heavy metals such as lead, said surface being liable to be into contact with products of acid character, such as alcohols e.g. cognac, whisky, wines or fruit juices, or acid foodstuffs, with a view to prevent said heavy metals from drifting into said acid products, characterized in that it comprises forming in a superficial area of said surface, after partially removing the lead ions from said area, a silico-aluminous diffusion barrier opposing said drift into said acid product, by ion exchange between said material having a vitreous structure and a coating temporarily laid upon said surface, said coating comprising a silico-aluminous crust resulting from the heating of a kaolin layer laid upon said surface under the form of a thixotropic slip of pure hydrated aluminum silicate.
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