Techniques : Heating lead into glass with colored elements and gilding grooves on mirrors
Making process (in detail) :

1. Glass decoration design :
   Specify the style of glass placement for each piece, considering the position to be uniquely decorated with the glass and that not to devalue the tradition of the artwork. For example, when designing a Buddha image base, a traditional, beautifully auspicious, and in line with the era of art pattern must be chosen. For this piece of work, Phra Narai Khon mask needs to be decorated with Krajok-krieb made by an artisan in Nonthaburi province.
2. Substrate Preparation :
   Ancient Glazing is the science of alchemy, a type of alchemy that converts minerals from one form to another. As a result, different types of minerals are mixed to form a mirror with a multi-colored luster, which consists of 2 parts, namely the glass layer and the lead layer.
   - The glass layer is the top portion of the glass containing pure lead, kaolin or white soil, and color elements from different colors of natural minerals to be mixed according to the compound ratio and grinded with an iron mortar to become homogeneous, called “Ya Si”. When it is heated, the surface will shine like a colorful mirror based on the color of the natural minerals. Then sieve it to separate out unwanted dust, wood or plant waste. to prevent unwanted chemical reactions. The elements that give natural color are
   Green Insect Wing color : comes from green rock minerals or Malachite containing copper oxide or copper.
   Amber color : comes from Khao Tok Phra Ruang ore or Pyrite containing iron oxide.
   Blue or navy blue or Kab color : comes from minerals that contain cobalt. The same type used to write porcelain.
   Red ruby color : comes from pure gold ore.
   Purple color : comes from minerals that contain manganese
    - The lead layer is the bottom part of the glass. It is made from pure lead or in Lanna language called “Jin”
3. Heating cracked glass :
   In this process, it is divided into 2 parts, namely the glass layer and the lead layer.
   The glass layer : Put the finely ground colorant powder into a crucible in a furnace with a heat of 800 - 1,000 degrees celsius until it becomes a honey-like liquid glass. Then pour the liquid glass water onto a flat stone slab such as granite, jade, agate, or Naga Suai, which these stones do not absorb heat. Make the glass water dry naturally by pouring the glass water sheet to the same thickness throughout the piece in the desired thickness.
   The lead layer : While pouring liquid glass water, put pure lead into a crucible in a furnace heated to 400 degrees Celsius until lead becomes liquid lead water. Then pour liquid lead water over the previously poured liquid glass and it becomes the shiny sheet of glass with lead plastered on the back surface, called “cracked glass” or Krajok Krieb.
4. Decoration of cracked glass on the workpiece :
   Cut the cracked glass into pieces according to the shape, size and color specified in each position of the workpiece by using “Thuekrak”, which is a mixture of pearl or shell charcoal mixed with black rubber until it is sticky and black, to bond the glass with the work piece. A proper way to install glass is to push a piece of glass down until Thuekrak streaks stick out from the sides. Then attach the next piece at about 1 millimeter. This Thuekrak, called “Saraek”, can help hold the glass piece and prevent rainwater seeping into that workpiece. It is usually used with outdoor decoration. However, for work that is in the shade may not need Saraek and can be decorated with mirrors closed to each other.

The glass gilding art was classified to be one of the lacquer-works in the Traditional Arts group of craftsmanship, called “glass gilding art”. It is a fine art used to decorate consumer goods and architecture by cutting glasses into small geometric pieces such as rhombuses. rectangle, triangle, hexagon, etc. With the properties of a mirror surface that has shimmering light, resulting in a jewel-like luster when hit with the sun ray. The glass is also a material that is durable to the climate, both sunlight and humidity as well as prevents the decorated objects from deteriorating easily.

It is assumed that the glass gilding art has existed since the Sukhothai period. There is also a mention of the art in the Ayutthaya period through the De La Loubère’s writings. There are some apparent evidences of the art in the Rattanakosin period, especially during the reign of Phra Bat Somdet Phra Nangklao Chao Yu Hua, King Rama III, which is considered the heyday of the art work decorated in various temples. The decoration on the Chofah, Bai Raka, and gable was changed from Thai lacquer work to glass gilded work. In the reign of Phra Bat Somdet Phra Chom Klao Chao Yu Hua, King Rama IV, he preserved the glass gilding making process by established the “Glass gilded production Department”, which was separated from the Office of Traditional Arts. The department was run by with her Prince Krom Khun Worachaktranuphap, His Royal Highness Pramoj. He supervised and figured out the method of making the stained glass. In addition, there is also a school of glass decoration in the throne room of the Tha Phra palace in order to disseminate the art. However, the department was dissolved in the reign of Phra Bat Somdet Phra Chulachomklao Chao Yu Hua, the King Rama V.

Besides in Thailand, the glass gilded art appeared in various provinces in the north of Myanmar, such as “Kaew Angwa”. For this reason, the wisdom of stained-glass production is found in many areas close to Thailand where Ratchaphon is the descendant of the Tai Khoen family. “Tejaya”, the 4th generation, that inherited the Krieb and Jin mirror knowledge along with their scientific studies in using natural minerals. Both types of glasses have the same production process. The differences as follow.
- Krajok Krieb : It has a unique feature. Its thickness is as thin as a crisp rice. It is brittle and can be broken easily. It is usually used to decorate on a flat surface or on the works that requires details, such as making the flower pattern, attaching at the corners of a low-relief dimension works. It is often found in various art works the central region.
- Krajok Jin : The word “Jin” means lead in the Lanna language. Its special feature is that it is thicker than Krajok Krieb . It can be bent and flexed. Its surface has cracking pattern. It is commonly used with wooden workpieces. It is usually found in Lanna art.
These types of mirrors share a common feature. The two layers of mirror cannot be separated from each other, which is different from European stained glass that can be separated by using a scientific process to remove the paint from the glass. However, the mirror made with the Thai glass gilding method cannot do so.

Apart from the knowledge that has been inherited within the family, being able to work as a royal artisan to restore the lion base of the Phra Si Sakymuni buddha throne in the grand hall of Suthat Thepwararam temple, which is a restoration under the royal patronage, allowed Ratchaphon to apply his knowledge of chemistry from his studies and being a teacher, into practice by practicing an alchemy of extracting the mineral elements from the purest Krajok Krieb in the reign of King Rama III. This was the beginning of the ancient Krajok Krieb art and the knowledge of the elements that presented color in those day: there were only 5 colors, namely green, yellow, white, red, and pale blue (blue or navy blue). Other colors used are added with some minerals in the later period.

Reference :

• Academic Group of Thai Artists Office of Traditional Arts, Fine Arts Department. 2008. Knowledge about “The work of gilding to decorate the glass”. Bangkok: Fine Arts Department.
• Julatat Payakaranon. 2007. “Glass Craftsmanship.” Royal Institute Journal 32 (4): 866-872.
• Ratchaphon Taejaya, Interviewed by V View Go Co., Ltd. 2023. Knowledge of making the traditional mosaic art (15 March).
• Institute for the Promotion of Thai Arts and Crafts (Public Organization). 2022. “Ratchaphol Taejaya: Arts and Crafts Teacher, Year 2022.” https://www.sacit.or.th/th/detail/2023-01-06-14-00-26

Compiled by :

• Knowledge Promotion and Dissemination Department Office, Handicraft Value Promotion Institute, Promotion of Thai Arts and Crafts (Public Organization)
• We will Go Co., Ltd.

Date of last data recording : 5 May 2023