February 2, 2010

Odor Slope: Concentration and Intensity

Normally as concentration of an odor increases so does the intensity of the scent.

Function that describes correlation between odor concentration and perceived intensity is called Odor Slope and looks like:

Concentration^Odor Slope=Intensity

For example, Musk Xylene has Odor slope of 0.30 that means that in order to achieve a 2 fold increase in odor intensity concentration should be increased 10 times!

While Odor Slope variations can be rather pronounced, it is generally Ok to use 0.30 as the average value.

But relationships between concentration and intensity of odors are rather different. For some essential oils intensity of the odor may noticeably increase with higher concentration of the odorant, while for other oils change in intensity may not be so obvious.

Low-slope odorants at first may appear as week in 100% concentrations, while higher-slope seem overpowering at full concentration. Comprehensive tables for Odor Slopes are hard to find (if you know a good reference, please add it here as a comment).

What is important to understand though is that when you double concentration of an odorant its intensity on average will be increased by mere 23% (2^0.3=1.23).

Have fun with your creations!

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