// Definition
Lines Per Inch — the standard measurement for mesh screen density used in dry sift hash making. The relationship is counterintuitive: higher LPI means smaller openings. A 60 LPI screen has openings of approximately 250 microns, while a 90 LPI screen has openings of approximately 180 microns. Understanding the LPI-to-micron conversion is essential for selecting the right screens for different stages of the sifting process.
// From the Episode
LPI was explained in detail in Episode 2, where the two-screen trick was introduced. The counterintuitive nature of the measurement was emphasised — beginners often assume that a higher number means a larger opening, but it's the opposite. More lines packed into each inch means each opening is smaller. The practical application is screen selection: a 60 LPI screen (250µ) serves as the work screen where material is agitated, while a 90 LPI screen (180µ) below it catches the falling trichome heads while filtering out larger contaminant. This LPI system is distinct from the micron ratings used on Bubble Bags, which measure opening size directly.
// Source
Ep. 002 Hash Church Episode II →