I love the aromas, the surprisingly effective impact they have on health--and yes, the chemistry! I'm especially interested in essential oil components. I've been blending from a component perspective for many years now, and have found the approach really effective.
Component Blending with Sitka Spruce
Let's consider Sitka Spruce (Picea sitchensis). Sitka has a nice percentage of beta myrcene (β-myrcene). I like β-myrcene. (I admit, I have molecular preferences--come on don't you?) As molecular structures go, beta myrcene seems simple, sweet, helpful and easy to relate to. I know, calling a molecule "sweet" means that some people have just closed their browsers and are no longer reading this post!
There is solid research on the properties of β-myrcene. It is analgesic, anti-inflammatory and sedative. Oils high in β-myrcene are likely to be good painkillers, and can be used in strong dilutions for short periods of time to reduce pain. We say "likely," because research results for a component's medicinal properties don't necessarily mean the essential oils with those components will all behave in the same way. That being said, many times we find the essential oils high in those components do behave in the same ways as the components.
The current batch of Sitka Spruce I have from Aromatics International has about 23.5 percent β-myrcene. When blending from a component perspective, I look for other oils with a significant percentage of β-myrcene. Mastic and Lemongrass can both have significant percentages, and may add to the blend's analgesic, anti-inflammatory and sedative effects.
Although I'm really fond of component blending, there are many other considerations and approaches I utilize with each blend (for example, blending by aroma, energetics or plant part). I find that considering multiple approaches for each blend offers me an effective way to choose the oils, the carriers and the method of application.