Essential Oil of Everything II - questions

Various oils, notably methyl salicylate, are used to "clear" samples of tissue (like moth brains). The tissue goes in opaque, and come out transparent. How? Does it denature the "colored" proteins? I'm stuck on thinking of the fixed tissue as being like glass, but then i realized i don't know why glass is transparent or opaque. I know it is jumbled up at the molecular level....but I think air bubbles make it opaque. If you melt your own glass (CF. fulgurites) it is usually not clear. At first I was thinking of the absorption spectra of each protein contributing to the "white" of opaqueness, but now I am thinking of these second-order effects of how the proteins are organized (parallel or cross-linked or jumbled)...