How to make marijuana BHO easily and safely
List of contents
With this first post about the famous and dangerous BHO, we introduce a new category in our blog, Resin Extractions. In this post we will propose a few safety rules for making this cannabis oil safely, avoiding any risk.
What is BHO?
BHO is a marijuana extraction known not only for its high cannabinoid and terpene concentration, but also for its dangerous method of extraction, which uses N-Butane, a highly flammable gas. Its name, Butane Honey Oil, comes precisely for the use of this type of gas as solvent. If we make an extraction of this kind with dry and frozen green matter, the result will have a rocky texture, while if we use dry matter without freezing it the final product will be an oleoresin. Either if we choose one method or the other, we can eliminate any trace of waxes, fats and lipids later on, achieving the renowned Absolut or Shatter. We are working on more posts about advanced extractions of our marijuana strains , but we consider that firstly we should know how to make this kind of extraction safely.
Basic advices before making BHO
As we know, N-Butane is highly flammable and volatile, so we should prevent any kind of risk before starting the process, for both us and people around us.
- Never make this extraction in a closed room, it should always be done outdoors.
- No smoking during the process, avoid anyone near you to smoke during the extraction/purge.
- Use a fan with plastic blades to eliminate the vapours generated during the purging process, the electrical connection may be too near the gas evaporation.
- A fire extinguisher can save your life in case of accident.
- A blanket can be usefull in case of a small fire.
- Use security gloves. The tube gets frozen when the gas passes through it, with the possibility to burn our hands.
- Do not wear synthetic clothes. It is better to use cotton-linen clothing, since synthetic fabrics can generate a spark.
Basic concepts of BHO
N-Butane is a relatively non-polar solvent that we use to achieve an extraction more pure and clean, for this solvent does not extract water-soluble parts like chlorophyll and other unwanted substances. For example, when we make an extraction using ethyl alcohol, chlorophyll releases very quickly, giving the product a dark green colour and a sour taste. The yields of these concentrates are lower than with other methods, and basically depend on the quality of the marijuana used, the size of the buds, their drying and curing conditions, etc. Usually, yields are between 5% and 18% of the total weight of green matter used. High THC cannabis strains are perfect for making these extractions, which can be made following different methods: the Open extraction, the cheapest and most used system, in which the gas passes through a borosilicate or metallic tube filled with buds, releasing the resin glands which fall in a plate where we collect them.
Closed loop: A more sofisticated method since we need a closed loop extractor. This device consists of a tank where the N-Butane is stored, valves that alllow the gas to pass through a column full of green matter, and another inner small tank where we collect the oil. With this system we can also take back all the remaining gas.
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Terpens and decarboxylation of cannabinoids
Apart from cannabinoids, inside the marijuana plant we also find a huge number of terpenes, which combine their flavours and effects. Some of these terpenes are very aromatic alcohols which release molecules freely at room temperature, like ketones, phenols, esters, ethers and aldehydes. We have to be sure about how we are going to use this oil: if we want it for medicinal uses (ingested, not smoked) we should decarboxylate it first, so we transform acid cannabinoids like THCA and CBDA into THC and CBD. This is done by heating the oil above 40 degrees celsius for about 30 minutes; however, if we heat the oil we are losing a considerable part of terpenes. On the other hand, if we want to smoke or vaporize it, we don't need to decarboxylate it, thus achieving better taste and effects.
How to get a tastier BHO
Although N-butane is non-polar, it does have a low water solubility, what causes the release of unwanted parts of the plant - like chlorophyll - throughout the extraction process. At 20º/ 68F it is a 0,0325% of Volume. This proportion for 1 litre would be: 1l= 1000 ml X 0.0325= 32,5 ml water soluble parts, enough to dirty our final product. The final purity depends widely on the chosen extraction method, this is why following the right steps is so important. Freezing the weed works great, although we must remember that the green matter has to be properly dried before. It is also important that during this process the marijuana does not get humid, for it could appear a layer of frost covering the trichomes that will make the extraction process much harder.
We also have to purge the gas contained in the oil, what can be done in different ways: slow heating (bain Marie), fast heating or using vacumm pressure. With this extraction we are trying to keep the maximum number of terpenes intact before they oxidize, getting the particular flavour of these concentrates. This is why it is so important starting with a healthy marijuana crop , since it will allow us to get a product with the maximum number of terpenes and cannabinoids.
It is advisable to use the main buds of the plants, where most resin glands - and terpenes - are produced. If we use the lower parts, stems or trim, the result will be a milder taste and effect. A new method for extracting BHO is "Fresh Frozen", which allows us to extract high quality resin by freezing fresh flowers - not dried - trying to capture the water inside them and thus extracting intact resin glands. The intensity of the flavour and aroma of this product is high grade.
