JOURNAL Perfume decant journal. Practical articles for choosing, testing and understanding perfume decants. How to test perfume without rushing Why perfume deserves several wears before a final opinion.3 ml, 5 ml or 10 ml: choosing the right size A practical comparison of common decant sizes.What decants are and how to use them A short guide to testing perfume through 3 ml, 5 ml and 10 ml decants.