The BIOCENTIC Edit

Castor oil guides from BIOCENTIC: ricinoleic acid explained, USP grade vs cosmetic grade, and how to use castor oil on hair, lashes, skin and nails.

USP Grade vs Cosmetic Grade Castor Oil: What's the Difference?

October 20, 2026

Most castor oil bottles say "pure". Fewer say USP grade. The difference is a published standard, and whether the oil has been tested against it. What USP grade means USP... Read more...

What 90% Ricinoleic Acid Means: How to Read a Castor Oil Lab Report

October 20, 2026

Castor oil labels love the word "pure". A lab report is how you check it. Here's what ricinoleic acid is, why the percentage matters, and what else to look for on a certificate of analysis. What is ricinoleic acid? Ricinoleic acid is the fatty acid that makes castor oil unlike any other plant oil. It has an extra hydroxyl group in its structure. That's why castor oil is so thick, and why it clings to hair and lashes instead of sliding off. What's a normal percentage? Castor oil is mostly... Read more...