How to see if your weed is contaminated

How to see if your weed is contaminated
Luke Sholl

Struggling to spot contaminated cannabis? Find out how to check if your weed contains glass, silica, or harmful chemicals.

One of the biggest, arguably most powerful arguments in favour of cannabis legalization is the fact that it allows us to take the industry out of the hands of organized crime units and instead create a regulated, reliable, and high-quality product.

This is great news for anyone living in an area where cannabis sales are legal and regulated. Unfortunately, the vast majority of the world’s cannabis users are still faced with prohibition, meaning they might find themselves buying weed from some not-so-reliable sources.

One of the biggest problems facing cannabis users in illegal markets, apart from the obvious legal issues, is the quality of the product they're buying. In areas where cannabis sales are still illegal, it isn’t unheard of to come across “contaminated weed.”


Cannabis can be contaminated in a number of ways. Contaminated cannabis is often called “grit weed.”

Grit weed is a common term used to describe contaminated cannabis. It refers to any type of cannabis that is laced or stretched with some kind of foreign substance, giving it a gritty or sandy texture.

Grit weed is usually sprayed with anything from sugar and sand to tiny glass or silica particles in order to increase the weight of individual buds and make the weed appear richer in trichomes.

There are also reports of people adding powdered laundry detergent to weed in order to make it seem like it produces a lot of “kief,” and some dealers are also said to spray their weed with diesel fuel, skunk spray, and perfume, or storing it in a closed container with cheese or fruit peels all in order to recreate the aromatic profiles popular signature strains.

Alternatively, cannabis can also be contaminated when it isn’t flushed properly.

Flushing is a process that involves passing large amounts of water through the soil of flowering cannabis plants in order to “flush” the soil and the plants of any chemical build up.

Plants are usually flushed right before harvest.

While flushing is considered an essential process by most growers, some may skip it and end up producing weed with a very harsh, chemical taste and smell.

Lastly, cannabis can also be contaminated or “laced” with other, oftentimes harder drugs. While this isn’t super common, some dealers are said to lace their weed with harder drugs to hide the poor quality of their product.

Some people also purposefully mix cocaine or LSD into their joints to create a “primo” or “rainbow joint.”


The danger of contaminated weed

The dangers of consuming contaminated weed are obvious.

Most of the products used to make weed appear more potent or smell differently (such as diesel fuel, glass, silica, laundry detergent, and skunk spray) are usually highly toxic and definitely don’t belong inside your body.

The same goes for any of the products that may contaminate your weed if it hasn’t been flushed properly. It’s not uncommon for cannabis cultivators (especially those working in unregulated, illegal markets) to use chemicals to boost the yield of their plants or protect them against pests and/or mold.

When plants aren’t flushed properly, these chemicals remain in the plant matter and may enter your body either via your lung (when you smoke or vape) or your digestive system (when you eat cannabis).

Finally, any harder drugs mixed in with your cannabis unintentionally can alter your high and create side effects that you may not be prepared for.


It is literally impossible to test weed for chemical contamination unless you have access to a scientific laboratory. However, there are at least some basic ways you can test your cannabis to make sure it's not “grit weed.”

Start by examining your buds with a magnifying glass and keep an eye out for any larger crystals, especially along the stems.

Also try rubbing a bud between your fingers and try to feel for any chalky or grainy textures caused by sand, glass, or sugar that your weed may have been sprayed with.

Next, make some kief either by grinding your weed in grinder with a kief catcher or by rubbing it against a stocking or silkscreen. Then put the kief on clean surface, roll a glass over it and listen for any distinct scratching or cracking sounds.

If you hear any of these sounds, you’re weed may contain tiny glass or silica particles.

Alternatively, you can also carefully rub the kief from your weed on a blank CD and see if that causes any scratches in the disc.

Next, assess the smell of your weed. Place it in a jar or clean ziploc bag, stick your nose inside, and take a long, deep breath, taking note of any strange odours that shouldn’t be there (like perfume, for example). High-quality weed should have a pure, clean smell.

You can also light a small sample of your weed and examine the smell and taste of the smoke. Again, quality weed should taste and smell “good.” if you notice any weird, distinct chemical smells/taste, we suggest you proceed with caution.

One final way to check your weed for contamination is to examine the ash from a joint, blunt, or bong. Contaminated cannabis and “grit weed” will usually form a hard ash (sometimes particularly black in colour) that stays in place when you tap your joint on the edge of an ashtray for example.

Obviously, the issue of contaminated weed is more likely in areas where cannabis is illegal and therefore unregulated. However, as more and more places around the world change their policies on medical and recreational cannabis use, users will hopefully get access to a reliable, higher quality product.

Luke Sholl
Luke Sholl

Fascinated by the wellness potential of nature, Luke has spent over a decade writing about cannabis and its vast selection of cannabinoids. Creating, researching and writing content for Cannaconnection, alongside several other industry-related publications, he uses strong technical SEO skills and diligent research to bring evidence-based material to thousands of unique visitors.