Influence of Flame and Hydrofluoric Acid Treatment on Surface Damage of Tableware

Rim area is a critical part of tableware with respect to corrosion in dishwashing process and also during sensitive in organic lustre decoration. The goal of this study was to analyse influence of both process the thermal treatment and HF etching on glass surface composition. Glass samples coming from production were analysed using visual assessment, optical microscopy, Scanning Electron Microscopy (SEM) and Electron Microprobe Analysis (EMA-EDXA). Surfaces treated by flame during edge melting showed significant decrease of sodium (average 7%) and increase of organic carbon (till 71 atom %). The same locations exhibited surface damage during dishwashing and lustre decoration. The inner side of the critical surface showed only slight dealkalization (average 3%), while glass surface without secondary flame treatment did not differ incomposition from glass bulk. Surfaces etched by HF were depleted by sodium (average 30%), enriched by calcium and potassium (average 18-43 %). Also CaF₂ presence was found out as a result of crystallisation. Inspite of a different composition from a bulk, no damage was never observed after HF application during lustre decoration. Presence of organic carbon originated probably from reduction flame seems to be more important formentioned type of damage as the differences in glass compositions caused by heat treatment