TOTD 100708: worthwhile difficult materials

[Guest guest]

Certain aromatic materials are difficult to work with; many of these

need to be diluted in order to be usable. Some may be more rewarding

than others in terms of rendering them usable.

What difficult absolutes, concretes, or otherwise, have you found to

be particularly rewarding once diluted?

What unexpected materials need preparation?

Other than dilution and hot-water baths, what techniques do you use

to make materials usable?