Silver plating of glass (making a mirror)

mirrorSilver plating of glass (making a mirror).

Polish the glass with a water-based suspension of slime chalk or magnesium oxide, degrease after rinsing. Prepare two solutions:

(A) 9 Dissolve g sugar in 100 cm3 distilled water, add 0,5 cm3 (a few drops) concentrated nitric acid, cook through 10 min, add after cooling 18 cm3 of ethyl alcohol. Prepare at least one day before use. The solution is stable and can be stored for any period of time. You can use sugar instead 10 g glukozy, adding nitric acid and cooking is then unnecessary;

(B) 1 Dissolve g of silver nitrate in 100 cm3 distilled water, add the solution 0,5 g of potassium hydroxide v 50 cm3 distilled water. Brown silver oxide precipitates. Add dropwise, constantly stirring, diluted 1:5 ammonia water up to the point, when a small amount of undissolved sediment remains at the bottom of the pan. Excess ammonia produces poor quality mirrors. Please note, that the solutions of silver nitrate and potassium hydroxide forming a solution (B) can be stored separately as long as required (first in a dark bottle), however, their mixture with ammonia should be prepared immediately before use. Storing it may explode!

Preparation of the silvering bath: the entire amount of solution (B) mix with 6 cm3 of solution (A) in a photo bathtub. The given amount is sufficient for silvering approx. 40 cm2 of the glass surface. For larger size tiles, the amounts of both solutions should be increased accordingly. Immerse the glass plate in the prepared bath and keep the liquid in motion, by rocking the tub continuously. The silvering process takes approx. 20 min. Take the silver-plated plate out of the bath, grabbing the edges of the glass, rinse several times with distilled water and dry at room temperature.

Protect the silver-coated surface, by painting with paint, composed of red lead and varnish, using a soft brush for painting. After the paint is dry, remove the silver tarnish from the other surface of the glass, by wiping with a cotton ball moistened with diluted 1:10 nitric acid, but without touching the edges of the glass, to prevent acid from getting under the protective paint, immediately rinse thoroughly with water and dry.

The inner surface of Christmas balls can be silver plated in a similar way, and give the color by painting external surfaces with varnishes. Silver coatings obtained by this method are very thin and easy to wear off, Therefore, they are not suitable for decorating glass or porcelain vessels.