The glass milk frother: why glass is better than stainless steel or plastic

Every morning you make a cappuccino. Or a matcha latte. Or just warm milk for the kids. And every morning you use a milk frother. But have you ever thought about what the inside of that frother is made of?

We explain why glass is the best choice — and why most milk frothers on the market have a hidden problem.

What’s inside most milk frothers?

Most milk frothers have a metal interior with a non-stick coating. Handy for cleaning, but that layer contains — you guessed it — PTFE or another PFAS material. Milk is heated to 60–70°C, and at that temperature small amounts can already be released, especially if the coating gets damaged.

Plastic frothers are a different category. Cheaper, but plastic and hot liquids aren’t a good combination. Especially if it contains BPA or phthalates — two substances used in many types of plastic that can disrupt hormones.

Why glass wins

Glass is chemically inert. It doesn’t react with milk, heat, or acid. Nothing leaches out. No PFAS, no microplastics, no BPA. Full stop.

Borosilicate glass — the type Safecourt uses — is also heat-resistant to above 100°C and shock-resistant. It’s the glass used for lab equipment. Strong, safe, and transparent.

That transparency is underrated, by the way: you can see exactly when the milk has reached the right froth texture. No guessing.

Crystal vs. Onyx: which one suits you?

Safecourt has two glass milk frothers:

Crystal — the classic glass milk frother. Simple, sleek, PFAS-free. Froths cold and hot. Best product of the year 2025–2026 according to the expert jury.

Onyx — the digital version with display. The same glass interior, but with precise temperature control and separate programs for:

• Cappuccino
• Latte
• Baby milk (45°C exactly)
• Plant-based milk (oat, soy, almond — each reacts differently)
• Hot chocolate

If you’re a morning person who just wants something fast: Crystal. If you want control over every degree and every texture: Onyx.

Tips for the best froth results

• Use chilled milk — cold milk froths better than milk at room temperature
• Whole milk froths the richest. Semi-skimmed works well too. Plant-based milk: choose a barista version
• Don’t fill to the rim — milk doubles in volume when frothing
• Wash the frother straight after use — dried-on milk residue is harder to remove
• For oat milk: the Onyx has a dedicated plant-based milk program that keeps the temperature exactly right

View the Crystal and Onyx milk frother →