Acid etching of glass

Acid etching was already known of in prehistoric times. Numerous acid etched items have been found dating back to as early as 1000 BC. The exact chemicals they used is unknown.
In 1860 – 1870 acid etching was first indutrially used for frosting of glassware. 

Acid etched glass vase (Dorothy Thorpe)
Glass etching is a style of glass decoration with frosted finish.
Acid etching is done by reaction of the glass surface with acid. The acid eats parts of the glass surface and roughens up the smooth glass surface. This roughening of the glass surface makes the glass translucent: the frosting effect. This type of etching of glass is therefor also called 'acid etching'. 

The acid is hazardous not only on contact but also the fumes are very toxic.

The acid can be in liquid form or can be in cream form.
Liquid is used for etching large surfaces, like a whole vase or a window. Etching creams are ideal for making designs on glass. 
A masking foil is used to cover the areas which must not be etched. 

Acid Etching of glass as a hobby

Acid etching is a fun hobby and, by using etching cream, also relatively safe to do at home.
Etching wine glasses or making etched glass awards, is easy to do at home and the results are great. 

Acid etching with etching cream is the preferred way to decorate small quantities of glassware and with the right tools it is ideal to make nice designs on wine glasses or personalize any glassware.

Manually etched tumblers

Here are the steps to etch a design onto your glassware. 

Things You Need:

· Etching cream (available from any crafts store)
· Vinyl sticker (available from any crafts store)
· Utility knife
· Disposable gloves
· Bucket of warm water
· Glass cleaner
· Dish cleaner 
· Paper towels
· Foam brush
· Glassware
· Safety glasses! 

Industrially etched glassware
  • Wash the glassware you are going to etch with glass cleaner and dry it completely with the paper. 
  • Make a drawing of the design that you want on the vinyl sticker. Cut out the parts which you want to be etched, with a utility knife. Remove the cover paper from the adhesive side and stick the vinyl on the glass. 
  • Put on your gloves. Using a foam brush, apply a thick, even amount of etching cream onto the design area. 
  • Wait for 15-20 minutes. 
  • Carefully wipe off the etching cream with paper towel after 20 minutes and dispose the paper towel properly as etching cream is very acidic and harmful if it comes in contact with the skin. 
  • Remove the gloves,and wash the etched glass with warm water and dish cleaner so as to remove any residue of etching cream. 
  • Remove the vinyl and finally clean the glassware with glass cleaner and paper towel. 
  • The glass etching is complete.

Industrial Acid Etching

Glassware factories usually don't use etching cream for their artwork. On industrial scale the preferred method is acid etching with a liquid acid solutions. 
The acid solution is either a solution of hydrogen fluoride in water or a solution of ammoniumbifluoride in water. Sometimes a mixture of ethyleneglycol and propyleneglycol is used instead of water.

Acid etching is easy to automate and several fully automatic machines are available in the market. These machines produce up to 5000 etched pieces per hour, bottles or drinkware, etc.

It is also advisable to automate this acid etching process because of the health risks that come with the acids. The acid etching machines are usually closed systems and the operators are not exposed to the acids.