The cannabis world is packed full of widely shared beliefs and strange myths – many of which the origin has now faded into obscurity. Take, for example, the persistent rumour that George Washington was a fully-fledged stoner, getting high on his own supply from his hemp plantation. Or that holding in your breath for longer after a toke will get you higher.
Sure, these urban legends are fun to believe and repeat to friends but, in most cases, there is very little evidence to support them. But what about the type of rumour that relates to the quality of our cannabis?
Take, for example, the common belief that the colour of the ash left in your ashtray after smoking a joint is a surefire way to determine the quality of your cannabis. It is widely believed that white ash proves that your cannabis has been “flushed” or well-cured, while black ash indicates that your bud was grown using too many fertilisers, sterilisers, and other chemicals. This widely circulated “fact” is repeated all around the world between stoners intent on consuming only the very best weed. But is there any truth to it?
As you can imagine, few – what we would call – studies have been carried out in this area. For some reason, researchers and scientists don’t appear to be interested in what the colour of cannabis ash means… But some non-cannabis-specific research may help us to determine whether this tale is fact or fiction.
The colour of ash in other settings
Luckily, some research has been done to assess ash left behind by other substances. Notably, the tobacco industry has been conducting research into its own products for decades. While these studies may not have been focused on determining what colour ash was “best”, some of their findings may be relevant to us.
Primarily, the aim of these studies was to determine which of tobacco’s ingredients promoted or inhibited the burning of their cigarettes. This led to further research to determine the effects of fertilisers on tobacco smoke and ash.
The use of fertilisers was found to have no impact on either the alkali composition or the sulphur levels in the leaves of the tobacco. But what did have an effect, was the fermentation (also known as ageing) process – which is now considered an essential process for improving the qualities of tobacco.
I know what you’re thinking: what does this have to do with ash colour? Right? Well! A recent study, which investigated the influence of certain microbiota and metabolites during tobacco fermentation, reported that effective fermentation resulted in improved aroma quality, combustibility – oh, and lighter coloured ash. In fact, the researchers boldly state, “white is the best, followed by gray.”
Ageing, curing, and moisture levels
So, it seems that effective fermentation or “ageing” of tobacco helps to improve the product quality and yield white ash. But what about curing and flushing cannabis? What does this actually mean, and does it have an impact on the quality of cannabis buds and the colour of ash left behind?
Well, like fermentation, curing can also be looked at as an ageing process. Recently harvested cannabis flowers should undergo a period of curing before they are consumed. Evidence suggests that this can help to boost the properties of the plant and reduce the moisture levels. Like in tobacco preparation, curing also causes a significant reduction in chlorophyll in cannabis leaves. However, there is currently little evidence to suggest that less chlorophyll equals whiter ash. On the other hand, moisture levels – which drop during the curing stage – may play a role.
Moisture levels can significantly affect the combustion of plant matter. As you would expect, plants with higher moisture levels don’t burn as efficiently as dried plant matter. Furthermore, incomplete combustion – which occurs when the material being burned doesn’t reach optimum burning temperatures – usually yields a darker ash. In contrast, effective combustion tends to yield lighter, and even white, ash.
In fact, research into wildfire ash indicates that burn temperatures play a major role in the properties of ash – including its colour. Furthermore, ash produced from low-temperature combustion is still rich in a number of organic compounds, of which carbon is the main component. At higher temperatures, carbon is volatilised (it turns to gas), leaving behind ash composed mainly of magnesium, calcium, sodium, potassium, silicon, and phosphorous. Oh, and guess what? The tobacco industry used to add magnesium and calcium acids to their tobacco to accomplish a white ash!
The term “flushing” refers to the process of washing out any leftover nutrients from the cannabis plant. Essentially, this means that, for the last few weeks of cultivation, the cannabis plants will be absorbing only water, as opposed to a nutrient solution. Effective “flushing” of cannabis has been said to increase the smoking quality of the plant, but it remains unclear whether this is actually the case. It is therefore unclear whether any effect of flushing on ash colour is related to a higher quality product.
The final conclusion
Based on the available evidence, it appears that the main reason behind the lighter ash of some cannabis comes down not to flushing but more likely to the temperatures applied during combustion. To this end, effective curing appears to make the formation of whiter ash more likely and, as curing is largely associated with a more smokable product, it may be said that white ash does mean better quality.
But, when all is said and done, there is little solid evidence to support the theory that light is right. After all, there are many factors, aside from combustion temperature and moisture levels, that can influence the quality of your cannabis. So, in conclusion, it’s probably best not to place too much stock in myths like this one.