#blending guide

There're no hard and fast rules about how much essential oils should be added to a finished product. In fact, many will agree that, when it comes to aromatherapy and maximising the therapeutic qualities of essential oils, stick to the principle of Less Is More if you don’t want to end up wasting money.

Below is a general guideline on the dilution rates of essential oils in relation to 30 ml or 1 oz of the finished product, unless otherwise stated:

Anointing oil – 10% dilution (60-75 drops)

Bath – 6-12 drops in a bathtub of water

Bath oil – 2-3% dilution [pour 15 ml (1 tbsp) of the blend into a tub of running water]

Bath salts – 5-10 drops per 120-240 ml (½ -1 cup) Epsom salt

Compress – 1-3 drops per 240 ml (1 cup) water

Creams – 1.5% dilution (8-10 drops)

Diffusers – 6-10 drops or as per package instructions

Face mask – 1 drop

Foot bath – 3-5 drops per 950 ml (1 quart) water

Inhalation – 1-2 drops on a piece of tissue paper or inhaler bottle

Lotions – 1.5% dilution (8-10 drops)

Massage oil (body) – 2.5% dilution or less

Mouthwash – 1 drop

Perfumes – 25 drops per 10 ml (⅓ oz) carrier oil. Perfumes typically have dilution rates between 15-30% essential oil, 70-85% carrier oil or alcohol base.  Perfumes with a concentration of 30% essential oils are typically applied only to the pulse points on the body.

Room spray – 30-50 drops per 240 ml (1 cup) distilled water

Shampoo – 2% or less dilution

Shower cream/gel – 2% or less dilution

This guideline applies to both using a single essential oil or an essential blend.

Essential oils (e.o.) are curious things. On the one hand they are curative yet on the other lethal. Some smell obnoxious one moment but sublime the next. The factor in question is, of course, dilution.

Since dilution involves calculation, yes it’s math again, I’ll try to simplify it the best way I can.

First of all, essential oils are measured in drops (for home use anyway), and to dilute them, you’ll need to add them to a vegetable based carrier oil. In every teaspoonful of carrier oil, which is equivalent to 5 ml, there are:

1 tsp = 5 ml = 100 (drops of oil)

and, to express 1% in decimals,

1% = 1 ÷ 100 = 0.01

so, 1% dilution in 5 ml would be:

0.01 x 100 drops = 1 drop

In summary,

1% dilution means 1 drop of e.o. in 5 ml (1 tsp) of carrier oil. 2% dilution means 2 drops of e.o.l in 5 ml (1 tsp) of carrier oil. 3% dilution means 3 drops of e.o. in 5 ml (1 tsp) of carrier oil.

In terms of fluid ounces (oz), 6 tsp makes 1 oz, and based on the above

1 oz = 6 x 1 = 6 tsp or 6 x 5 = 30 (ml)

so 1% dilution is equivalent to

1 x 6 = 6 (drops of e.o.)

consequently, 2% dilution is equivalent to

2 x 6 = 12 (drops of e.o.)

Therefore, in summary:

1% dilution means 6 drops of e.o. in 1 oz (30 ml) of carrier oil. 2% dilution means 12 drops of e.o. in 1 oz (30 ml) of carrier oil. 3% dilution means 18 drops of e.o. in 1 oz (30 ml) of carrier oil.

Now, this is all well and good if you’re making small amounts or single dosages. What if you want to make larger amounts? There are 2 ways to do this:

Measuring by Volume

Bearing in mind we’re calculating in percentages, then it makes sense to think not in terms of drops but volume.

For example, what volume of essential oil should be added to 500 ml of carrier oil to make a 2% dilution?

2% of 500 ml is

(2 ÷ 100) x 500 = 10

10 ml of e.o.

Measuring by Weight

Another way to do this is by weighing. You’ll need to purchase an electronic scale that is sensitive enough to measure in grams since it’s unlikely that you’ll be making batches in kilograms.

Firstly, find out the weight of 1 ml of oil. Chances are your weighing scale will show 1 g. Remember to Tare the empty container, weighing without content, before you pour the oil into it.

So, based on the above calculation, you will add 10 g of e.o. to 500 g of carrier oil to make a 2% dilution.

During my online research on aromatherapy, I came across a term familiar among many but spoken of only by a few – Blending Factor (BF). Here's a summary based on my limited understanding of the topic:

definition

Blending factor (BF) is an arbitrary numerical value assigned to an essential oil based on its aromatic strength. The value ranges between 1 and 7 (some would go as high as 10) with "1" being the strongest-smelling and "7" the mildest.

application

How do you assign BF to essential oils? You can begin by first selecting, from among all the essential oils that you possess, the strongest and the mildest smelling essential oils. Then, base on those two extremes, compare and rate the rest of the essential oils one at a time. For example, if I have a total of 12 essential oils, I would probably want to:

use a smaller scale: 1 – 7

choose the strongest smelling essential oil: Vetiver

assign the BF to it: Vetiver (B1) where B stands for Base note

choose the mildest smelling essential oil: Bergamot (top note)

assign the BF: Bergamot (T7)

choose the next: Birch (top note)

compare it to Vetiver, Bergamot and the remaining 9 oils.

assign the BF: Birch (T2)

repeat Steps 6 through 8 for the remaining oils.

adjust where necessary.

As you can see, from the above example of Birch essential oil, Blending Factor doesn't necessarily correspond to Perfume Note. They are not the same simply because they measure different properties of essential oils. That means to say, while Blending Factor rates essential oils in terms of strength, Perfume Note is based on the volatility of the aroma or how long-lasting it is.

In fact, if you've been checking out the essential oil profiles provided in this blog, you'll make the Scent Life–Perfume Note as well as Scent Impact–Blending Factor connections.

Before you jump on the wagon...

limitations

Blending is not just about finding out proportions and calculation. Life would be so easy if it were so simple and the world would end up smelling more or less the same. Why so? It is limited precisely because:

it measures only one property of the essence;

the rating itself is subjective and arbitrary;

it ignores the complexity of the compounds within each essential oil; and, more importantly,

how these compounds interact with one other when combined;

it doesn’t take into account safe dosages when applied on humans;

comparison works well when there are only 2 variables;

nose fatigue when assigning Blending Factors;

oxidation or the aging process within a blend.

The way I see it is that Blending Factor is useful only on paper – it helps by giving me a starting point before I actually begin the blend. If you try blending using only BF calculation, you'll soon realise how flat everything seems to end up smelling. Think of it as cooking. I don't know how you feel about Thousand Island salad dressing but I sure as hell don't want to have it on my salad every day!

So, never use it on its own, especially for therapeutic purposes because there are many other factors involved which are more crucial.