Not all glass is the same
Most glass you encounter in everyday life is soda-lime glass: the standard type used for basic tumblers, supermarket drinkware, and decorative pieces. It is made primarily from silica, soda ash, and lime. It is inexpensive to produce and adequate for cold drinks. But it is sensitive to temperature changes and can crack or shatter when exposed to sudden shifts between hot and cold.
Borosilicate glass is a different material entirely. Made by adding boron oxide to molten silica, it behaves fundamentally differently from regular glass. It is stronger and lighter, significantly more resistant to thermal shock, and maintains its clarity over time without clouding or absorbing flavours. It is the type of glass used in laboratory equipment, high-quality cookware, and scientific instruments, anywhere precision, heat resistance, and durability matter.
T2 uses borosilicate glass across the entire glass range because tea demands more from its vessels. Hot water goes in from the moment you pour. Sometimes pieces are moved from a warm kitchen to a cool bench, or used for both hot tea in the morning and cold-brew in the afternoon. Regular glass does not handle that range of use reliably. Borosilicate does.
Why borosilicate glass works so well for tea
There are three qualities that make borosilicate glass particularly suited to tea.
The first is thermal performance. Borosilicate glass handles freshly boiled water without the stress that would crack standard glass. For those using a Trendglas Water Kettle or pouring a full pot of hot water into a glass teapot, that reliability is not a minor detail.
The second is flavour neutrality. Glass does not absorb any taste or aroma, which means it does not carry flavour between different teas. There is no ghosting of yesterday's chai into this morning's green tea.
The third is visibility. You can watch the tea brew. Watching the colour deepen as the leaves open, particularly with whole-leaf teas, is genuinely satisfying and tells you something about when to stop steeping. It turns the making of tea into something worth paying attention to.
Double-walled glass: worth understanding
Several pieces in the T2 glass range are double-walled, including the Gigi Glass Double Walled Mug, Bee Moroccan Glass Double Walled Mug, Hammered Glass Double Wall Mug, and the Ribbed Double Walled Glass Tumbler. Double-walled construction means the glass has two layers with a small air gap between them. This air gap acts as insulation in both directions: it keeps hot drinks warmer for longer, and keeps the outer surface of the vessel cool enough to hold comfortably without burning your hands. In cooler New Zealand weather, particularly in Wellington, the South Island, or on an autumn morning anywhere in the country, the difference is noticeable.
Handblown glass
Some pieces in the T2 glass range are handblown by artisans using traditional glassblowing techniques. Molten glass is gathered on the end of a hollow pipe, then shaped through breath, rotation, and simple hand tools. No two handblown pieces are exactly the same. Subtle variations in form, slight differences in wall thickness, or tiny air bubbles visible when held to the light are not imperfections but signatures of the hand that made them. They are why a handblown borosilicate teapot can feel remarkably delicate while remaining fully capable of handling boiling water.
How borosilicate glass was developed
The material was developed in Germany in the late 1800s, when glassmakers were trying to solve the persistent problem of ordinary glass cracking when exposed to heat. The breakthrough came from adding boron to molten silica, which reduced thermal expansion and dramatically increased strength. The new glass found immediate application in laboratories and scientific instruments, and its qualities were eventually recognised as ideal for cookware and tea vessels.
Caring for your glassware
Most borosilicate glass pieces are dishwasher safe on the top rack, though handwashing is gentler on any decorative detailing and will extend the life of the finish. Avoid sudden temperature changes even with borosilicate glass. Let pieces cool before placing them in cold water. Handle with care near hard surfaces as, while resistant to thermal shock, glass will crack under impact like any other material.
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