--- title: 'Glass teaware' url: 'https://howtotea.me/teaware/materials/glass' markdown: 'https://howtotea.me/teaware/materials/glass.md' lang: en date: '2026-10-25' description: 'Glass teaware: borosilicate versus ordinary glass, which vessels come in glass, which teas suit it, and how to keep boiling water from cracking it.' --- # Glass teaware 玻璃茶具 Editors · October 25, 2026 · 10 min read Glass hides nothing: you see the leaf, the color of the liquor and the sediment. But not every glass can take boiling water, and a thick wall is worse than a thin one. ![An empty glass pitcher and a glass cup of golden tea](https://howtotea.me/images/c/o/v/e/r/cover-26250150.webp) Illustration 玻璃茶具 Glass bō li chá jù Main trait: transparency For boiling water: borosilicate 3.3, marked “耐热” Best for: delicate green, yellow and jasmine tea Weak spot: thermal shock, worst in thick walls Oldest find: tea set from Famen Temple, 874 People choose glass teaware for one reason: to see what is going on inside. The leaf unfurls, the liquor darkens, fine bits settle on the bottom. You cannot watch that through porcelain or clay, so glass comes out when the tea is worth watching or when you need to see at a glance that the infusion is ready. There is a catch. Glass conducts heat poorly and cracks under boiling water more often than any ceramic, so a lot depends on what kind of glass a piece is made of and how you handle it. ## Which glass Glass teaware is made from three kinds of glass. They look much the same but behave very differently. **Soda-lime** glass (钠钙玻璃) is made from silica, soda and lime, the stuff of cheap tumblers and mugs. According to the manufacturer Schott, it survives a temperature difference of 65 K with walls under 4 mm, 50 K at 4 to 6 mm and 35 K at 6 to 15 mm.[1](#fn:1) Pouring boiling water into a cold tumbler like that is a gamble. For boiling water you want borosilicate glass (高硼硅玻璃), which contains boron oxide. It is used for gaiwans, fair cups, teapots and double-wall cups. In the same measurements it withstands 175 K with walls under 4 mm and 160 K at 4 to 6 mm, 2.5 to 2.7 times more than ordinary glass. Corning's figures tell the same story: 160 versus 65 °C for a thin plate.[1](#fn:1) Chinese consumer sources more often say “about 150 °C” for borosilicate and “about 50 °C” for ordinary glass. The exact numbers vary from source to source; the order of magnitude does not. **Tempered** glass (钢化玻璃) is ordinary glass that has been heat-treated so that the surface is in compression and the core in tension. It handles thermal shock better than annealed glass, more than twice as well by Corning's data. The composition stays the same, though, and so does the expansion coefficient of about 9·10⁻⁶ K⁻¹, so a tempered diner tumbler is no substitute for borosilicate teaware. Consumer articles quote “200 °C” for tempered glass, but the source behind that number gives neither wall thickness nor test method. Thickness works against you. When boiling water goes in, the inner layer of the wall expands before the outer one, and heat spreads through glass slowly. The thicker the wall, the bigger the difference between the layers and the greater the load. So “thicker means sturdier” does not hold for boiling water: in Corning's data the allowable difference drops as plates get thicker (160, 130 and 90 °C for plates of 3.2, 6.4 and 12.7 mm). ## What is made of glass - **Tumbler for [green tea](https://howtotea.me/teas/green)** (玻璃杯), around 200 ml. You brew in it and drink from it, as in [grandpa-style brewing](https://howtotea.me/brewing/methods/grandpa-style). - **Glass gaiwan** (玻璃盖碗). You can see the leaf through the side, but the glass heats up right to the rim, which makes this kind of [gaiwan](https://howtotea.me/teaware/brewing-vessels/gaiwan) awkward to hold. - **Fair cup** (公道杯). Here glass makes sense: nothing is brewed in a [chahai](https://howtotea.me/teaware/brewing-vessels/chahai), and everyone at the table can see the color of the liquor. On a gongfu table, that is the most obvious use for glass. - **Glass teapot with a [strainer](https://howtotea.me/teaware/utensils/strainers)** (玻璃茶壶). This is the European and Japanese way: the leaf sits in the basket, the liquor in the body. TeaGuardian's reviewers consider thick-walled glass teapots acceptable, unlike gaiwans. - **Water kettle** (玻璃煮水壶). It heats water like any other [water kettle](https://howtotea.me/teaware/utensils/kettles). Only put it on a flame if it is marked for open fire. - **Double-wall cup** (双层玻璃杯). The air gap between the walls keeps your hand from getting burned. China has a separate industry standard for these cups, QB/T 5035-2017. - **Glass hirachawan** (ガラス平茶碗). A wide, shallow Japanese bowl for summer [matcha](https://howtotea.me/brewing/methods/matcha): the tea cools faster in it, and the green shows through the wall. It comes out mainly in July and August. These pieces are blown into a mold or on a pipe, or pressed. In Hejian, in China's Hebei province, a glassblower blows a piece on the pipe in under a minute. ## Which teas suit it Lin Zhi of the Tea Research Institute at the Chinese Academy of Agricultural Sciences recommends a glass tumbler for delicate famous green teas: [Xihu Longjing](https://howtotea.me/teas/green/longjing), Dongting [Biluochun](https://howtotea.me/teas/green/bi-luo-chun), [Junshan Yinzhen](https://howtotea.me/teas/yellow/jun-shan-yin-zhen) and [Huangshan Maofeng](https://howtotea.me/teas/green/huangshan-mao-feng). In glass you can watch the leaf sink slowly through the water, the so-called “tea dance.” He advises against a teapot for these teas: it holds a lot of water, which cools slowly and “stews” the leaf. A clear tumbler also suits jasmine tea made from delicate leaf. ![Jun Shan Yin Zhen buds standing upright in a glass](https://howtotea.me/images/i/g/l/y/-/igly-v-stakane-1c363c21.webp)Illustration The Tea Drunk tea house takes the same approach. Its staff brew green and [yellow tea](https://howtotea.me/teas/yellow) in an open glass vessel with no lid, because in their experience glass and thin porcelain hold the least heat and keep the leaf from overheating. Not everyone agrees. In an experiment at South China Agricultural University, water in a glass tumbler was still hotter after ten minutes than in a [Yixing teapot](https://howtotea.me/teaware/brewing-vessels/yixing) or a porcelain gaiwan, and over the first two minutes it was the gaiwan that cooled fastest. The mass and shape of the vessel probably matter as much as the material. Taste has been tested too. In a 2024 study by Guo and colleagues, with vessels of equal volume, tea brewed in a glass set contained fewer tea [polyphenols](https://howtotea.me/science/chemistry/polyphenols), free [amino acids](https://howtotea.me/science/chemistry/theanine) and soluble sugars, and was darker and yellower than tea from porcelain.[2](#fn:2) [White tea](https://howtotea.me/teas/white) brewed in glass scored well for freshness and sweetness but poorly for body. Pewter did best for green and white tea, porcelain for black, and Yixing clay for [oolong](https://howtotea.me/teas/oolong) and [dark tea](https://howtotea.me/teas/dark). So glass is for teas where the look of the leaf and a lower temperature matter. For dense oolongs and dark teas, clay or porcelain is the usual choice. Green tea in a tumbler Use 3 g of leaf for 200 ml of water (about 1:50), at 80–85 °C (176–185 °F). Steep the first infusion 30–60 seconds, the second 40–90. Top up when a third of the water is left, no more than three times. For jasmine tea from delicate leaf, use 2–3 g and water at about 90 °C. The sources give no glass-specific settings for white, yellow, oolong or dark tea. Use the settings for that type of tea and go by the color of the liquor. ## Using it safely 1. Read the marking: “耐热”, “高硼硅”, or the Japanese 耐熱ガラス with a stated temperature difference. 2. Check the vessel for chips and cracks. Makers advise throwing damaged glass away, and it should never be heated. 3. Do not pour boiling water into unmarked thick-walled glass: the thicker the wall, the bigger the difference between its layers. 4. Do not set a hot vessel on cold or wet stone, and do not wipe it with a wet cloth. 5. On a flame, use only kettles marked for open fire. Japanese labeling rules describe the test: the glass part is held in a thermostat for 30 minutes, then plunged into cold water for one minute, and it has to survive the stated temperature difference. Borosilicate is not indestructible ISO 3585 states plainly that the nominal properties do not mean the ware can be abused freely anywhere in the 20–300 °C range. A kettle on a stove needs an open-fire marking, a low flame and a central position. Wipe drops off the outside, and never heat it empty. Wash glass without abrasives, steel wool or scouring powder. For the rest of your teaware, see [care](https://howtotea.me/teaware/care-and-collecting/care). ## How to choose - **Marking.** Testers at Donghua University note that many makers print only GB 4806.5-2016 on the box. That is the mandatory minimum for [lead](https://howtotea.me/teaware/care-and-collecting/teaware-safety) and cadmium, not a standard for the product itself. Also look for GB/T 35596 for blown borosilicate, QB/T 4162 for tumblers and QB/T 5035 for double-wall cups. Tempered ware carries the mark “钢化玻璃器皿 / TEMPERED”. - **Clarity.** Borosilicate is usually clearer and soda-lime cloudier, and the cloudiness is sometimes disguised with frosting. Held up to the light, a good piece shows no bubbles, inclusions or scratches. - **Thickness.** A thick base and thick walls are a risk with boiling water, not a sign of strength. - **The word “liuli”.** In shops 琉璃 usually means cast art glass, though historically it was the old general word for any glass. For tea it guarantees nothing. ## How glass got into tea Glass was known in China as early as the Western Zhou, but glassmaking developed slowly until the Qing. The old name was 琉璃, with 料器 also used in the Ming and Qing. The word 玻璃 is a loanword. The earliest known glass tea set was found in 1987 in the underground palace of Famen Temple, which was sealed in 874. The inventory on the stone stele lists it as “琉璃茶椀柘子一副”, one tea bowl with a stand. Both pieces are pale yellow and mold-blown. The bowl is 4.9 cm high and 12.5 cm across, the stand 3.6 cm high and 13.7 cm across (other publications give slightly different sizes). The shape is typically Chinese, like a zhan bowl on a stand, yet analysis showed plant-ash soda-lime glass close to that of Nishapur rather than the high-lead glass usual in China.[3](#fn:3) Scholars disagree on where the pair was blown: by Chinese craftsmen from imported raw material, or possibly by Persians in Chang'an. Between the Tang and the twentieth century there is a gap: no Song or Ming text calling glass a tea vessel has turned up. In 1696 the Qing court set up a glass workshop with the help of the German Jesuit Kilian Stumpf, staffed mostly by craftsmen from Boshan and Guangzhou. The Palace Museum counts nine decorative techniques, among them single-color, overlay, aventurine, twisted and enamel-painted glass (a 2005 exhibition named eight). Modern heat-resistant teaware began in Jena. Around 1931 (the Metropolitan Museum dates it 1930 to 1934), the former Bauhaus student Wilhelm Wagenfeld designed a heat-resistant teapot for Schott with body, lid and strainer all in borosilicate. Today the main center is Hejian county in Hebei, “China's heat-resistant glass production base,” where teaware is one of six product groups. Estimates of its size vary: the Hebei government counts 502 enterprises and 77,700 employees, while provincial TV reported more than 500 and more than 60,000 in 2025. ## Common questions Can I pour boiling water into any glass tumbler? No. Ordinary soda-lime glass handles a temperature difference of about 65 K, so a cold tumbler can crack when you fill it with boiling water. For hot tea, look for vessels marked “耐热” or “高硼硅” (borosilicate), with thin walls and no chips. Does glass change the taste of tea? Glass neither releases nor absorbs anything, but in a 2024 comparison tea brewed in a glass set came out weaker than in porcelain, with fewer polyphenols, amino acids and sugars. That is no problem for delicate green tea. For dense oolongs and dark tea, porcelain or clay is the usual choice. Why is a glass gaiwan worse than a porcelain one? The wall gets hotter and the gaiwan is awkward to hold. Reviewers at TeaGuardian tested several popular glass gaiwans, recommended none of them and found that tea brewed worse in them than in plain porcelain. Notes 1. SCHOTT, comparison of BOROFLOAT 33 and soda-lime glass, 2010: [howardglass.com](https://www.howardglass.com/wp-content/uploads/borofloat-vs-soda-lime.pdf). Corning data: [Thermal Properties of Corning Glasses](http://www.quartz.com/pxtherm.pdf). [↩](#fnref1:1) [↩](#fnref2:1) 2. Guo H., Pan Y., Li C. et al. Influence of Various Tea Utensils on Sensory and Chemical Quality of Different Teas. Plants, 2024, 13: 669. [PMC10933942](https://pmc.ncbi.nlm.nih.gov/articles/PMC10933942/). [↩](#fnref1:2) 3. Li Q., Henderson J. et al. Chemical Analysis of Tang Dynasty Glass Vessels from Famen Temple Using a Portable XRF. World Scientific, 2016. [ResearchGate](https://www.researchgate.net/publication/304138592). [↩](#fnref1:3) --- ## Navigation - Parent: [Teaware materials](https://howtotea.me/teaware/materials.md) - Previous: [Chinese ceramics and porcelain](https://howtotea.me/teaware/materials/chinese-ceramics.md) - Next: [Metal teaware: tetsubin, silver, tin and copper](https://howtotea.me/teaware/materials/metal.md)