Calcium Sodium Borosilicate

Calcium Sodium Borosilicate is an inert glass/mineral used mainly as a cosmetic filler or shimmer pigment (often a few percent in makeup), and it is generally not chemically reactive on skin. However, as a particulate it can cause mild mechanical irritation or micro-abrasion in highly reactive or compromised skin (especially around eyes or on eczematous areas), so it is not scored as fully inert for patient-safety reasons. Safety Notes: Calcium sodium borosilicate is used primarily as a pearlescent/brightening filler (often as micronized glass or as part of composite “powder” blends) in color cosmetics and some leave-on skincare; at the low end it appears as a trace opacifier/soft-focus additive in serums, primers, and lotions around ~0.01–0.5%. The highest consumer-available levels are seen in high-payoff illuminators, highlighters, shimmery body products, and some pressed/loose powders where borosilicate glass can be a major component of the powder phase, commonly ~5–20% and occasionally up to ~25% in shimmer-heavy products. It is uncommon in rinse-off products except at low levels for optical effect, since high loads provide little benefit and can feel gritty.