The number of actual drops can vary greatly and is especially dependent on the viscosity (thickness) of the oil and the dropper or orifice reducer used.
20 drops ….. 1 ml
75 drops ….. 1 teaspoon
You probably won’t get the same result twice.
Drops are so inaccurate in terms of weight that you can weigh the same number of drops from the same bottle of essential oil several times and you are likely to get a different result. I challenge you to try this for yourself at home too.
Measurements will also vary between suppliers.
Essential oils will vary by batch, by supplier, by geographical region, by plant origin, by growing conditions, etc. etc. etc. In other words, you can buy three different batches of essential oil from three different suppliers and it’s likely that 20 drops of all three essential oils will weigh different to each other.
The opportunity for human error is enormous. You can easily get distracted by something happening around you and you can lose count. You don’t have equipment measuring the drops for you, so you rely on your own ability to count to 20. I like to think that I’m pretty good at counting to 20, but even so I had to keep myself in check a few times as life was passing me by.
Furthermore, the viscosity of the essential oil can cause error in counting too. If the liquid has a low viscosity and drops out of the bottle quickly then you might not be able to keep up. If the liquid has a high viscosity and takes forever to drop out of the bottle, then you might become so bored that you get distracted and lose count.
Because essential oils are concentrated, highly potent substances, a working knowledge of how to use them safely is vital to the success of your efforts. The potential hazards of an essential oil depend on the compounds in the oil, the dosage and frequency used, and the method of application. Here are a few guidelines to ensure safe and effective use of essential oils:
- Don’t use undiluted essential oils on the skin. They can cause burning, skin irritation and photosensitivity. There are a few exceptions to this rule: it is acceptable to use the nonirritating oils lavender or tea tree undiluted on burns, insect bites, pimples and other skin eruptions-as long as you don’t have extremely sensitive skin.
- Use with caution those essential oils that result in photosensitivity. Citrus oils can irritate skin, and some of them will cause uneven pigmentation of the skin upon exposure to sun lamps or sunlight.
- Use with caution those essential oils that are irritating to mucous membrane (the lining of the digestive, respiratory and genito-urinary tracts) and skin. Keep all essential oils away from the eyes.
- Keep all essential oils out of the reach of young children; older children can be taught to respect and properly use essential oils, but they should nevertheless be supervised. In general, when treating children with essential oils use one-third to one-half the adult dosage and select only nontoxic oils. Among the best and safest essential oils for children are lavender, tangerine, mandarin, neroli, frankincense, petitgrain and Roman chamomile.
- Vary the essential oils you use. Using the same facial oil blend for a long period of time is acceptable because it covers a very small part of the body, but daily application of the same blend of oils over your entire body for more than two weeks is not recommended. It is wise to alternate with a blend of different oils containing different chemical constituents at least every two weeks. Uninterrupted use of some oils exposes your liver and kidneys to chemical constituents that may be harmful over time. Rotating the oils gives your body time to process them and allows each oil to work on different levels in its own unique way.
- Be extremely careful before take essential oils orally for therapeutic purposes. Safe ingestion of oils requires a great deal of training and is therefore not recommended for beginners.
- Use essential oils cautiously with those who are elderly, convalescing, or have serious health problems such as asthma, epilepsy or heart disease.
- Be cautious about using essential oils during pregnancy, especially during the first trimester. Even oils that are generally safe during this time may be too stimulating for women who are prone to miscarriage. Because so many oils are best avoided in pregnancy, it is easier to list the safe ones: gentle floral oils such as rose, neroli, lavender, ylang-ylang, chamomile and jasmine absolute, as well as the citruses, geranium, sandalwood, spearmint and frankincense.
- Overexposure to an essential oil, either through the skin or through inhalation, may result in nausea, headache, skin irritation, emotional unease or a “spaced-out” feeling. Getting some fresh air will help overcome these symptoms. If you ever experience skin irritation or accidentally get essential oils in the eyes, dilute with straight vegetable oil, not water.
This information was pull from http://www.healthy.net
The point of this is that essential oils need to be respected and used with caution.