Originally Posted by jsparla
Totally agree with Jan and David;
however, there seems to be one "additive" called Glucam P-20, which acts as a post-added fixative for top/middle notes:
Quote PerfumersApprentice: "This is a material used for the fixing of top and some middle notes. For example, experiments performed in house show that Sweet Orange essential oil (one of the most fleeting of scents- usually lasting only two minutes on the skin) was increased to last half an hour or more on the skin.
Use up to 5% of your fragrance formula concentrate, but experiment! Using too much will "flatten" a fragrance."
It's certainly true that Glucam P-20 works as a fixative and is more-or-less odourless, but I still don't recommend adding separately - if I use it I build it in to the fragrance formula - just like benzyl benzoate, which is also an almost odourless fixative.
Any fixative will have a differential impact on some components of the fragrance - so you may need to adjust other parts of the formula to compensate for it's effect - if you add some at the end the resulting fragrance will likely have more lasting power but may not smell the same as it did before you added it, even though the additive itself is odourless.
I realise that's counter-intuitive but is essentially the same thing that David and others have describe in relation to materials they are anosmic to: even if you can't smell Benzyl salicylate on it's own you can detect the smoothing effect it has when it's in the blend. Hope that helps.