From Project: Redcap
Vulgar Alchemy is a Mystery that allows the magus to discover and use new Shape and Materials bonuses. Described in TMRE, it is an Outer Mystery that is an 'open secret', available to any character at character generation.
The creation of new S&M bonuses using Vulgar Alchemy is a time consuming and arduous task, both in-character and as a matter of out-of-game book-keeping and seasons of work. If Vulgar Alchemy is the way the Order obtained and disseminated the S&M bonuses that are listed in the core book and supplements, it is reasonable that these are close to all of the widely-known ones. However, this does not preclude the introduction of a new S&M bonus by the storyguide.
If your troupe is very easy-going in regards to approving new S&M bonuses, the value of Vulgar Alchemy for the magus is very slim. There is, therefore, a tension between the usefulness of the mystery and the latitude of allowing unofficial S&M bonuses.