hydrolysis ratio, rw 

https://doi.org/10.1351/goldbook.HT07623
Mole ratio of water to alkoxy groups used in sol-gel processing of metal alkoxides.
Source:
PAC, 2007, 79, 1801. (Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)) on page 1823 [Terms] [Paper]