What Is a Borosilicate Test Tube Glass Infuser and How to Use It
By Welcome to The Indian Chai - Your tea your flavour! | Published: 2026-10-19
Category: How-to Guides
Learn what a borosilicate test tube glass infuser is, why it's a practical loose leaf tea brewing accessory, and how to use it step by step for a clean, flavorful cup.
Quick answer
A borosilicate test tube glass infuser is a portable, heat-resistant brewing tool made of food-grade borosilicate glass with a cork stopper. It lets you steep loose leaf tea directly in a cup or mug, then remove the infuser once your tea is ready.
Why choose a borosilicate test tube infuser over a traditional teapot
Unlike a full teapot or basket infuser, this test tube design is compact and travel-friendly. The borosilicate glass handles boiling water without cracking, and the fine perforations in the glass filter out most tea leaves, so you get a clean cup without needing a separate strainer.
One trade-off: the tube has a smaller capacity than a teapot, so it is best for single servings. If you are brewing for a group, you will need to steep multiple rounds or use a larger vessel.
How the cork stopper and glass filter work together
The cork stopper seals the top of the tube, preventing leaks while you stir or carry the infuser. The perforated glass bottom acts as a built-in filter, allowing water to flow through while keeping most tea leaves inside.
Because the filter is part of the glass body, there are no metal mesh parts to rust or clog. Rinsing the tube under running water after each use keeps it ready for the next brew.
How to use a borosilicate test tube glass infuser in 4 steps
- Add loose leaf tea to the tube: Remove the cork stopper and place about 1 teaspoon of loose leaf tea into the tube. Do not overfill – leave enough space for the leaves to expand as they steep. Overfilling can block the perforations and slow down water flow.
- Pour hot water into the tube: Hold the tube over your cup or mug and pour hot water (just off the boil for black tea, slightly cooler for green or white tea) into the tube until it is about three-quarters full. Replace the cork stopper securely. Leaving a little air gap helps the water circulate and prevents the cork from popping out.
- Steep for the recommended time: Let the tea steep for 2–5 minutes depending on the tea type. You can gently swirl the tube once or twice to encourage even extraction. Do not leave the leaves in the water too long, or the tea may become bitter. Set a timer – over-steeping is the most common mistake with this infuser.
- Remove the infuser and enjoy: Lift the tube out of your cup and set it aside on a saucer or small plate. The brewed tea remains in the cup, free of leaves. Rinse the tube with warm water immediately to prevent stains. Rinsing right after use keeps the glass clear and the cork dry, extending the infuser's life.
Product spotlight
- Borosilicate Test Tube Glass Infuser: Made of 100% food grade borosilicate glass, non-toxic and lead-free, with an oak cork stopper. You can pour boiling water directly into the tube without worrying about glass breakage or chemical leaching, and the cork provides a secure, natural seal.
Borosilicate Test Tube Glass Infuser
