Topic: Stylish Jade Green Uranium Glass Vase Frosted Outside

[Ekimp]

That’s what I was thinking. According to wiki, plastic wasn’t invented until 1907 and that was only Bakelite. Not sure how long a horse hair brush would last but it wouldn’t be easy to work with acid if the brush was dissolving 

[flying free]

reference source:  The Corning Museum of Glass  (my italics and bold and underlining)

https://www.cmog.org/glass-dictionary/acid-etching

Acid Etching

'The process of etching the surface of glass with hydrofluoric acid. Acid-etched decoration is produced by covering the glass with an acid-resistant substance such as wax, through which the design is scratched. The object is then immersed in hydrofluoric acid, or a mixture of dilute hydrofluoric acid and potassium fluoride is applied to etch the exposed areas of glass. Acid etching was first developed on a commercial scale by Richardson’s of Stourbridge, England, which registered a patent in 1857. An effect superficially similar to weathering can be obtained by exposing glass to fumes of hydrofluoric acid to make an allover matte surface.'

[Ekimp]

Apologies for resurrecting this but I saw an interesting (but not desirable) fairly modern heavy cut glass vase today. It had diamond panels between cuts that had clearly been frosted by hand using a grinding wheel.

I looked online for examples of other more modern glass that might have been frosted by mechanical means and found this Yugoslav Zajecar bowl https://www.ebay.com/itm/Vintage-Kristal-Zajecar-Bowl-made-in-YUGOSLAVIA-Crystal-Frosted-Dish-/174317179660 . It has been frosted over a large area around the entire circumference with what must have been a coarse grit. You can clearly see (in the last three photos) the horizontal marks from the grit, you can even see where ‘fleabite’ chips have been knocked of the edges of the frosted areas by the coarse grit. The glass moulding has soft rounded corners, the only sharp edges are where the surface has been ground away by the frosting. The frosting around the entire circumference must have been done by spinning the bowl against an applied abrasive. I can’t see that frosting by acid (liquid or fumes) or sand blasting could possibly show the marks and finish on this bowl.

The finish on this bowl is rather rough but I believe if a finer grit had been used, then a finish close to that on my two vases would be achieved.

[Ekimp]

I have been looking at acid etching in British Glass 1800-1914 by Hajdamach, specifically Northwood’s work on pages 184/185. This consists acid etched line boarders, shaded between borders with frosting. Reading about Northwood’s earlier technique, Hajdamach says:

 “The effects produced by Northwood’s [acid etching] machines consisted only of outlines. If the areas inside the figures were to be shaded the glass was passed to the engraving shop. Broad copper wheels were used to matt [or frost] the surface...” [my square brackets]

He does go on to say this was a time consuming process but I presume this would primarily be because they were shading by hand between complex lines rather than covering an expanse of surface without interruption. Northwood then develops an acid etch frosting treatment used in conjunction with resists (which was a quicker process in this application) that was applied in a similar way to that described by flying free in reply #41 above.

On page 185 of Hajdamach, Plate 166 shows a Northwood jug with the mechanical frosting c1862 and Plate 167 a goblet with the acid frosting. The mechanical frosting on the jug looks to cover a large area representing the ground on the lower half of the jug in addition to the detail of the leaves and animals etc. Hajdamach shows that mechanical abrading was a technique used in 1862, purely to frost a surface.