"Originally Tea Tree oil production was from wild stands of trees in swampy areas. Harvesters were subject to snake bites and wasp stings."
They would gets cut and scratched from the branches and the hand tools also caused some injuries.
The huge amounts of vegetation required and quality of the trees harvested varied by location, and so the overall quality of the oil was varied. Today the oil comes largely from trees grown on plantations, and harvested mechanically by harvesters that have been specially modified for the industry.
The trees are harvested every twelve to eighteen months, and they may have a harvest life as long as ten years before being replaced. The modern methods of harvest allow for a fine cut product that is easy to handle and ready for steam distillation.
After harvest, the fine cut vegetation, consisting of chopped twigs and leaves is transported to the distiller. Here the materials are subjected to steam and as the vapors rise from the steamed leaves, it passes through a cooling chamber.
In the cooling chamber is where the water and oil returns to a liquid state, following which, the oil and water are separated leaving only the 100% tea tree oil. When the distillation is complete, and the oil has been separated out, it’s ready for bottling.The Australian Tea Tree Industry Association is very concerned with the quality and safety of tea tree oil, and so they have developed standards for your protection and theirs.
They warn that 100% tea tree oil should be stored, transported, and sold only in dark glass bottles. I have quoted here from their website
“As part of its responsibility to consumers, the Australian tea tree industry adheres to stringent legal requirements than ensure the quality and safety of its products.
Pure tea tree oil of more than 15ml in volume is bottled in ribbed dark glass bottles and fixed with a child-proof safety cap. Tea tree oil sold in clear glass bottles of greater than 15ml volume is not 100% tea tree oil. Pure tea tree oil should only be stored in clear glass containers for limited periods of time, as over-exposure to light will degrade its quality.
As members of the Australian tea tree industry are committed to excellence, all efforts are made to ensure that loss of quality does not occur during production, packaging and transport of their products. Note that such regulations do not always apply to tea tree oil produced and bottled overseas. “
Notice that they specify that “Tea tree oil sold in clear glass bottles of greater than 15ml volume is not 100% tea tree oil.” That’s roughly a one half ounce bottle! Notice too, that "such regulations do not always apply to tea tree oil produced and bottled overseas".
Please be aware though, that tea tree oil can be packaged in clear glass as well as in aluminum or stainless steel. The quality of essential oils is not protected by the color of the glass container, because the destructive ultraviolet rays pass just as easily through colored or clear glass.
Because of possible deterioration from light sources and heat, always store your essential oils in cool dark places.
There are many stores and businesses, especially here in the United states where you can purchase a very well known brand of tea tree oil, in a clear plastic bottle.
According to these standards, it is very possible that you are not buying 100% pure tea tree oil! And even if you are, notice that storage for more than limited periods of time combined with exposure to light may degrade the oil’s quality.