Chemistry of Christmas Ornaments

Of­ten, it doesn’t oc­cur to us to won­der where sim­ple things come from, and Christ­mas or­na­ments are no ex­cep­tion. The process of mak­ing frag­ile Christ­mas dec­o­ra­tions in­volves a whole man­u­fac­tur­ing sto­ry: the grad­u­al trans­for­ma­tion of a piece of glass into a tiny mas­ter­piece.

The process starts with cut­ting the glass, which is de­liv­ered to a fac­to­ry in the form of long, thin tubes. Such a tube is cut into small­er sec­tions known as blanks. The glass is then heat­ed to about 1000 °С (1832 °F), and it be­comes soft and duc­tile — some­what sim­i­lar to dough.

Glass is an amor­phous sub­stance, mean­ing that it doesn’t have a reg­u­lar crys­talline struc­ture. That’s why, upon heat­ing, glass be­comes less dense, which makes it eas­i­er to mold.

Next, a glass-blow­er shapes the blanks. Christ­mas or­na­ments with a rel­a­tive­ly sim­ple shape, such as balls and cones, are made by sole­ly the glass-blow­er, who ex­hales air into the glass blanks.

More com­pli­cat­ed shapes are pro­duced us­ing com­pres­sion molds. Af­ter the glass blank is heat­ed, a glass-blow­er puts it into a mold and ex­hales air with all his or her might.

Cu­ri­ous­ly, dur­ing this man­u­fac­tur­ing process, the glass is thinned to a frac­tion of a mil­lime­ter, be­com­ing as frag­ile as an eggshell.

Be­cause of its amor­phous struc­ture, glass is not very ther­mal­ly con­duc­tive. A glass blank doesn’t burn a mas­ter’s mouth and hands, even when its oth­er side is heat­ed to 700 °С (1292 °F)! Still, more com­plex Christ­mas or­na­ments are made in com­pres­sion molds. This in­cludes shapes such as San­ta Claus, snow­men, var­i­ous cars, stars, and so on.

Next, an or­na­ment must be cooled. To en­sure that it cools even­ly, the or­na­ment is held to a burn­er flame, and then the flame’s tem­per­a­ture is grad­u­al­ly low­ered.

Once the or­na­ment is cooled, it un­der­goes a sil­ver­ing process.

The sil­ver­ing process takes place in­side an or­na­ment. First, a sil­ver plat­ing so­lu­tion is poured into the fig­ure. This is usu­al­ly a so­lu­tion con­tain­ing sil­ver ions and a re­duc­ing agent, such as potas­si­um sodi­um tar­trate tetrahy­drate and glu­cose.

An­oth­er tech­nique in­volves alu­minum de­po­si­tion. Or­na­ments are placed in a spe­cial vac­u­um cham­ber and alu­minum foil is hung on a tung­sten wire. Next, elec­tri­cal cur­rent is passed through the tung­sten wire, caus­ing the alu­minum to evap­o­rate and pre­cip­i­tate on the sur­face of the or­na­ments.

Dur­ing the sil­ver­ing process, a glass blank is im­mersed in wa­ter heat­ed to about 50 °С (122 °F), where it is steadi­ly shak­en to pro­mote a chem­i­cal re­ac­tion. Sil­ver ions in­ter­act with mol­e­cules of a re­duc­ing agent, caus­ing the sil­ver to cov­er the glass sur­face in a thin, glossy lay­er.

The left­over so­lu­tion is dis­posed of and sub­ject­ed to a cor­re­spond­ing treat­ment. The or­na­ment prod­uct is washed and sent on­ward to the next step.

Adding a fin­ish­ing touch of paint can make an or­na­ment tru­ly fes­tive. In or­der to “paint” the sil­ver coat­ing cer­tain “col­ors”, an or­na­ment is im­mersed in a col­ored fin­ish. Its col­or and com­po­si­tion may vary — for in­stance, it may in­clude resin, a sol­vent, and an ani­line dye.

A mir­ror-like coat­ing in­side the or­na­ment can be seen through its walls. Any ex­cess of pol­ish is re­moved, af­ter which the or­na­ment is dried and con­tin­ues on to a painter for ad­di­tion­al hand­made dec­o­ra­tion or is pre­pared for de­liv­ery straight to stores.

The last step is shav­ing. A blank “leg” is pre-cut and capped with met­al and a loop, and the or­na­ment is packed for sale. This frag­ile beau­ty is fi­nal­ly ready to dec­o­rate your Christ­mas tree!

To­day, glass Christ­mas or­na­ments are grad­u­al­ly be­ing re­placed by plas­tic al­ter­na­tives that are cheap­er both in raw ma­te­ri­als and in pro­duc­tion costs.

How­ev­er, we can find fac­to­ries that pro­duce Christ­mas or­na­ments us­ing the good meth­ods of old. Such fac­to­ries still ex­ist in Ger­many, Poland, and Rus­sia.