[varispeed]

> material science however almost always all you need is a trial and error

Is it science if you essentially fiddle something until you get a result you are after and then try to fit a theory that would explain the result of the fiddle?

[fluoridation]

It is if you do it in a way that's reproducible, and if the methods used are based on already-known science. It wouldn't be scientific if there's only one machine in the entire world that can get the desired effect and nobody can figure out why, or if one of the steps involves praying to Cthulhu.