How to make a glass

In this century, the existence of glass is undeniable. Glass is everywhere in many forms as a bottle, window, mirror, etc. Nevertheless, do you know how to make a glass? Traditionally It’s quite simple and generally it’s merely consisted of three main steps : chemistry reaction, molding, and finishing. Firstly, primary materials of glass, such as sand, flint, spar, or some other siliceous substances (white sand) with one or other of the fixed alkalies (soda), and in some cases with a metallic oxide, mixed and kept in a storage furnace. Litharge (kind of lead preparation) as metallic oxide usually used but iron is preferred in bottle-glass. This materials must be reduced to powder before heating (For this purpose we can use mortars or by horse mill) and it sent to the calcining furnace for stirring and and then glass furnace with temperature controller for heating (5 or 6 hours) in 1700⁰ C. As the result is called frit as the best form to make a glass. To purify this coarse matter we can use flux such as lead, borax (for the best looking-glasses), arsenic, nitre, or any alkaline matter. Flux will bind the waste or unwanted substances.

Second step is molding. After cooling down, the compound is being removed through the pipes. This pipes are separated into two flows, one directed to a temporary storage to make the plate glass and the other one is directed to a removable mold to make the bottle glass. In the first flow, there is a rolling pin system, which is compound move below it, with flat mold for pressing the frit (glass compound) and make it into thin and flat form. The second flow is different. To make a bottle glass, the removable mold is filled by glass compound and then it blown to make bottle shape that we want. It’s blown until the compound is robust and hard.

Finally, the flat glass and the bottle glass are manipulated with additional process such as coloring, carving, decorating, etc. Those processes are depend to the function of the glass and of course to the costumer’s demand. Now they are finished and ready to used.

The Silent Theater "Ondel-Ondel"

Almost all of Jakarta’s people know or at least ever heard about “ondel-ondel”, but there isn’t a little of non-Jakarta people who don’t know exactly what is “ondel-ondel”. Ondel-ondel is a native art of Jakarta that comes from Betawi ethnic group, the native inhabitant of jakarta. It made from bamboo and specially formed so it’s easy to lift from inside, has a measurement of 2 x 3 m² with ± 80 cm radius, and decorated well so it looks like a Betawi’s handsome man or a betawi’s pretty woman. Face of Ondel-ondel is a red mask (male) or white mask (female), and its hair is made from palm fiber. Ondel-ondel is played by one person inside, so the big ondel-ondel may looks alive when dancing with special betawi’s music which is consisted of “tanjidor” (kind of trumpet) and “gendang” (kind of percussion).

In history, Ondel-ondels were firstly used to represent betawi’s ancestors that loyally protected their offspring or the villagers. Villagers believed that ondel-ondel was an amulet and preventing from wandering wicked ghost.

Nowadays, ondel-ondel is commonly used to adorn a party or to welcome honored guest, for example in the opening of a new building that just has been finished. Besides that, ondel-ondel is also commonly used to pimp Jakarta, especially in Jakarta’s anniversary, June 22th. All Main streets, hotels, and the center of city decorated with ondel-ondel, even there is an 6 m height of ondel-ondel at town square.

Jakarta fair, an event that consisted of exhibition and bazaar that only exists in Jakarta’s anniversary always decorated of Ondel-ondel, even ondel-ondel not only be decoration but also played here. Ondel-ondel becomes a special attractive thing in this event.