Krang (ครั่ง), known in English as lac, is the resinous secretion of scale insects of the family Kerriidae, most commonly cultivated as Kerria lacca; it is collected from host trees as stick lac and refined into seedlac and shellac [2], [3], [5]. A 1990 academic paper says Thailand has been one of the world's leading lac producers since the Second World War [6], and an FAO trade review, using figures for 1980–81 to 1989–90, puts India and Thailand together at about 17,000 tonnes a year, roughly 70 percent and 30 percent [5]. The Thai press accounts of amulet making checked here name stingless-bee nest material (ชันโรง) and lacquer (รัก) for sealing and finishing a bia gae; they do not name krang [13], [14].
Key facts
| Fact | Detail | Source |
|---|---|---|
| Thai name | ครั่ง (krang); the raw secretion is called ครั่งดิบ (krang dip) | [1] |
| Producer | Scale insects of the family Kerriidae; the most commonly cultivated species is Kerria lacca | [2], [3] |
| Trade forms | Stick lac, then seed lac (particles removed), then shellac (resin extracted) | [5] |
| Host plants | More than 400 noted; three carry most commercial cultivation: palas, kusum and ber (Ziziphus mauritiana) | [3] |
| Thai host trees | Rain tree (Samanea saman) is the common host in a Chiang Mai, Lampang and Phayao survey | [7] |
| Main producers | India and Thailand, about 70 and 30 percent of an average 17,000 tonnes (FAO table, 1980–81 to 1989–90) | [5] |
| Amulet sealing | Bia gae mouths are closed with chan rong in the press accounts checked; those sources do not name krang | [13], [14] |
What is krang (lac)?
Thai Wikipedia describes krang as scale insects of the family Kerridae, for example Laccifer lacca, whose secretion is called raw lac (ครั่งดิบ) and is described as reddish-purple [1]. English-language sources define lac as the resinous secretion of several lac-insect species, of which Kerria lacca is the most commonly cultivated [2].
Lac is an animal resin. Plant resins, by contrast, are mostly made of terpenes, and the English Wikipedia article on resin lists lac from Kerria lacca among the animal resins [11].
The English word lac derives from the Sanskrit lākshā, which stands for the number 100 thousand [2]. Thai Wikipedia says people in several civilisations have used lac for more than 4,000 years [1].
How does the lac insect make resin?
Kerria lacca belongs to the family Kerriidae, the lac insects, in the superfamily Coccoidea, the scale insects [3]. It was described as Coccus lacca in 1781 (formally published in 1782) by the Scottish surgeon James Kerr (1737–1782) in Patna [3].
The species produces a dye and a wax as natural secretions, and its first-instar larvae are called crawlers [3]. A 2022 review describes lac insects as bivoltine, with winter and summer generations each year; they stay attached to the host tree for life except for the crawler and the adult male [8]. Nymphs crawl out from minute pores and settle on twigs [8].
Shellac is scraped from the bark of trees where the female lac bug secretes it, and the secretion forms a tunnel-like tube [4]. Estimates of the number of lac bugs needed for 1 kilogram (2.2 lb) of shellac range from 50,000 to 300,000 [4].
Sources do not agree on the species name used in Thailand. Takeda's 1990 paper and Thai Wikipedia use Laccifer lacca [1], [6]. A 2016 Chiang Mai University study identified lac insects from six host species in northern Thailand as Kerria lacca by the shape of the female second-instar nymph [7]. A 2022 review lists K. chinensis for Thailand [8].
Which trees host lac in Thailand?
Worldwide, more than 400 host plants have been noted, and three produce most commercially cultivated lac: palas (Butea monosperma), kusum (Schleichera oleosa) and ber (Ziziphus mauritiana) [3]. The FAO review also names these among the principal host trees [5].
In Thailand, English Wikipedia lists rain tree and pigeon pea as the most common host plants [2]. Takeda reports that in northern Thailand lac was traditionally cultivated on wild host trees and that, since the rain tree (Samanea saman) was introduced "at the beginning of this century" (the paper dates from 1990), it has been grown in host-tree plantations [6]. The paper adds that most local people now believe the rain tree to be native [6].
A survey in Chiang Mai, Lampang and Phayao found six host species in five families: rain tree, Ziziphus mauritiana, longan, lychee, Albizia lucidior and Croton oblongifolius [7]. The rain tree was the common host [7].
The same study measured the colour of lac resin dissolved in alcohol. Lac from longan was light yellowish, with the lowest red value (a* 2.09), while lac from jujube and rain tree was dark red, with the highest red values (a* 3.28 and 3.07) [7].
How is lac produced in Thailand?
Cultivation begins when a farmer ties a stick carrying eggs ready to hatch to the tree to be infested, and thousands of insects then colonise the branches and secrete the resin [2].
Takeda describes lac cultivation, host-tree plantations and rice growing as one agro-forestry system in northern Thai farm households. The farmer grows lac in the agricultural off-season for short-term cash, and the unstable income from rice is supplemented in the long term by selling old host trees [6]. With rising world demand for seedlac, the paper says, Thailand became one of the world's leading lac producers after the Second World War [6].
A study of the supply chain in Lampang Province identified three groups. Farmers obtain brood lac, infect host trees, tend them and harvest. Minor compilers buy and sell stick lac; major compilers also dry it. Seed-lac factories buy from both groups and process the lac for sale at home and abroad [9].
How much lac does Thailand produce?
The FAO review (undated; its production table runs from 1980–81 to 1989–90, with Thai figures from Subansenee, 1991) says total annual world production is about 20,000 tonnes, with India and Thailand averaging 17,000 tonnes between them, about 70 percent from India and 30 percent from Thailand [5]. Its table of Thai exports, taken from Ministry of Agriculture and Cooperatives trade statistics, covers 1983 to 1990 [5]. It adds that the two countries each export about 6,000 tonnes a year on average, that Thailand exports the bulk of its output, and that production varies considerably with the weather [5]. English Wikipedia gives Thai lac exports of around 7,000 tons a year in the 1990s [2]. We did not find a current Thai production figure in a source we could fetch.
How is stick lac turned into shellac?
The FAO review defines stick lac as the crude product taken directly from the trees, seed lac as the product once particulate matter has been removed from the sticks, and shellac as the product once the resin has been extracted [5].
English Wikipedia describes the same sequence: harvested sticklac is crushed and sieved, the sieved material is washed repeatedly to remove insect parts, and the result is seedlac, which is processed into shellac by heat treatment or solvent extraction [2].
Shellac is mainly composed of aleuritic acid, jalaric acid, shellolic acid and other natural waxes [4]. The shellac article gives a melting point of 75 °C (167 °F) and notes that shellac dissolves in alcohol, typically denatured ethanol [4].
What is lac used for?
The FAO review lists uses in plastics, electrical goods, adhesives, leather, wood finishing, lacquer work, printing, polish and varnish, and ink, and calls lac the principal ingredient in sealing wax [5]. It also says lac yields an edible dye used to colour soft drinks and foods [5]. Thai Wikipedia lists shellac, lacquer (แลกเกอร์), utensils and ornaments among the industrial uses [1].
English Wikipedia says lac is used as a varnish for musical instruments and that India Post still uses it as sealing wax, though that use is being phased out [2]. The sealing-wax article adds that from the 16th century sealing wax was compounded from various proportions of shellac, with turpentine, resin and chalk or plaster; medieval sealing wax was typically beeswax and Venice turpentine [10].
A 2022 review says early use of lac was limited to decorating wood and as an adhesive for ceramics, and that lac dye is used in pill and food coatings and lac wax in fruit coating and bottle sealers [8].
What do Thai sources say about krang in amulets?
We looked for Thai government, journal and national-press sources saying that krang closes the mouth of a bia gae, coats a takrut or seals a phra kring, and found none. What the sources we did fetch say about those three amulets is below.
Bia gae (เบี้ยแก้)
Thai Wikipedia describes the bia gae as a เครื่องรางของขลัง made from a shell (เบี้ย) with mercury inside, then consecrated, and as an amulet for counteracting คุณไสย (sorcery); it does not name a sealing material [12].
A Thairath article of 8 June 2026 says mercury is put into the shell, the mouth is closed with a natural material such as underground chan rong (ชันโรงใต้ดิน), and the shell is wrapped in lead, silver or gold, then cord-wrapped and lacquered (ลงรัก) [13]. A 2011 Komchadluek column by อ.ราม วัชรประดิษฐ์ says the shell is plugged with chan rong, wrapped in lead sheet or cloth and tied with cord coated in rak or ยางมะขวิด; it calls chan rong the material used so that mercury does not escape [14].
Thai Wikipedia describes the chan rong as a stingless, bee-like insect whose nest material is sticky and waxy-looking, and says Luang Pu Boon of Wat Klang Bang Kaeo made bia gae and sealed them with chan rong [17]. None of these three pages mentions krang.
Takrut (ตะกรุด)
Thai Wikipedia says takrut are commonly made from thin sheets of gold, silver, nak, lead or other alloys, inscribed with an iron stylus; they may be wrapped with cord or sacred thread, and some texts call for dipping in lacquer and gilding (ชุบรักปิดทอง) [15]. The page also says takrut designs shrank over time from large, thick pieces made for war to small ones carried on the person [15]. It does not mention krang.
Phra kring (พระกริ่ง)
Thai Wikipedia defines the phra kring as a small Buddha image seated on a lotus base, usually with the right hand in the Māravijaya (subduing Mara) gesture and a medicine jar or healing fruit in the left palm [16]. It says making them began in Tibet and China and later became popular in Khmer lands, and that a small metal pellet (เม็ดกริ่ง) is placed inside so it sounds when shaken [16]. The page does not describe how the interior is closed and does not mention krang [16]. The 2011 Komchadluek column says some temples also use chan rong to plug the base of an image after the kring pellet, yantra sheets or other sacred items are put inside [14].
Krang, rak and chan rong compared
| Material | Where the sources checked place it | Source |
|---|---|---|
| ชันโรง (chan rong) | Closes the mouth of the bia gae shell over the mercury; some temples plug image bases with it | [13], [14], [17] |
| รัก (rak, lacquer) | Finish on the bia gae; coating on its cord; dip for gilded takrut | [13], [14], [15] |
| ครั่ง (krang, lac) | Not named for any of these uses in the sources checked here | none |