What is a Flash Point and why are they useful to know?

What is a Flash Point?

In chemistry it is defined as “ The lowest temperature at which an organic compound or volatile material gives off enough vapour to ignite in air given an ignition source.”

 

All essential oils have their own flash point and they are handy to know if you are making soap. This is because the soap can reach high temperatures of over 85°C during the saponification process and if all the essential oils you are using have low flash points, you may find that they all evaporate away during the making process and there is very little scent left in the soap at the end. A way to combat this problem is to blend the low flash point essential oils you wish to use with an essential oil or oils with a higher flashpoint to make them more stable.

They will also evaporate more rapidly in a bath or a vaporiser, so if you are looking for a scent to fill a room for longer or be more effective in a bath, blending is a useful way to increase the length of time they will last.

Another reason it is useful to know the flash point is that those essential oils which have flash points below 60°C are considered flammable and carry a “Flammable Liquid 3” warning sign in transit. They are therefore considered dangerous goods by couriers and they will cost more to ship and not be able to be shipped by air.

Some examples of essential oils with a low flash point are Sweet Orange, Grapefruit, Peppermint, Roman Chamomile and Black Pepper.

If you would like to know the flash point of a particular oil you can either give us a call and we can tell you, or ask us to email you with the Material Safety Data Sheet (MSDS). Alternatively you can find out for yourself by putting a couple of drops of essential oil into a saucepan of water and putting it over a low heat. Place a thermometer into the water, ensuring that it touches only the water and not the saucepan. Watch the thermometer carefully as the water temperature rises. Eventually you will see the essential oil begin to gently smoke as it starts to vaporise. The temperature at which this occurs is the oil’s flash point.