Oh! she was perfect past all parallel --So what has Don Juan's mother, Donna Inez, got to do with anything?
Of any modern female saint's comparison;
So far above the cunning powers of hell,
Her guardian angel had given up his garrison;
Even her minutest motions went as well
As those of the best time-piece made by Harrison:
In virtues nothing earthly could surpass her,
Save thine "incomparable oil," Macassar!
Lord Byron, Don Juan, canto the first, xvii
It is not Donna Inez herself that interests me, but Byron's reference to Macassar. This was the first substance I came across when wondering about Regency hair care. Now in woodworking circles "Macassar" is a type of Ebony, and is a very dark-grained wood. I had therefore always believed that Macassar oil must have had the effect of darkening hair colour (and the existence of antimacassars tended to confirm this in my mind).
A bit of actual research (well, sometimes guessing just doesn't do it) revealed however that Macassar oil is in fact colourless, and has nothing to do with Ebony except that both were imported from the same place, Macassar, a district in Sulawesi.
So Macassar oil is not the answer to my quandary. The search goes on.