Facial steamers are designed to deliver warm, soothing steam to open up pores, improve circulation, and hydrate the skin. One of the key components of a high-quality facial steamer is the glass used in its construction, particularly in the water reservoir and steam chamber. Most professional and high-end facial steamers use borosilicate glass, a material known for its exceptional durability, heat resistance, and chemical stability. Borosilicate glass is composed mainly of silica (80%) and boron trioxide (13%), making it highly resistant to thermal shock. This means it can withstand rapid temperature changes without cracking or breaking, ensuring safety and longevity in facial steamers. It also has a low thermal expansion rate (~3.3 × 10⁻⁶ /°C), preventing warping or structural weakening over time. Unlike plastic, borosilicate glass is non-toxic and does not release harmful chemicals when exposed to heat. It is also highly transparent, allowing users to monitor water levels easily. Additionally, its