Although hashish is an ancient form of solventless cannabis concentrate, the process of mixing ice water and cannabis flowers to produce it, the technique known as washing hash, is still a recent innovation. It wasn’t until the late 1980’s and early 90’s that the first hash runs were made by stirring together cold water and cannabis plant material, and gathering the resin as it separated from the rest of the material and settled to the bottom of a collection vessel. Later iterations of the process involved a series of filter screens to isolate and collect trichome heads from the slurry of ice water and cannabis.

Over time the ice water extraction and filtering method was improved upon, which gave birth to a series of nylon bags, known as hash washing bags, providing extractors with a spectrum of various grades of hash to choose from at the end of the wash. Today, the most reliable and consistent method of producing premium grade hash (the kind that’s definitely worth the trouble), is washing hash with a set of quality hash washing bags. 

The most prominent piece of equipment needed to wash hash is a set of quality hash washing bags, but that’s hardly all that is needed to produce a premium solventless product. The right equipment can take us only halfway there at best. Adhering to the correct process is what really delivers the results. 

Producing high quality bubble hash doesn’t follow an exact formula, as several variables need to be taken into account. These variables give some flexibility to the extractor, such as the type of starting material used, approach to mixing the cannabis and ice water, and method of drying the hash. The specific cannabis cultivar also impacts the outcome of the wash in a major way. 

These variables are inconsistent from one extractor to the next, and from one hash run to the next, which means that an exact recipe to follow each and every time is out of the question. However, there are some basic overarching tips that can be advantageous, despite the changing variables in equipment, approach, and techniques specific to the extractor. 

If you’re unfamiliar with the process of washing hash, check out our Guide To Washing Bubble Hash. This will provide a solid foundation upon which to apply the following tips and tricks. 

Tips and Tricks for Washing Premium Quality Hash

#1 Start with quality cannabis that releases copious amounts of resin
High quality hash doesn’t come from low quality cannabis. The cannabis material you wash needs to be of high quality, whether it’s fresh frozen or air cured. A great way to find out how your cannabis will perform is with a small test wash. Learn the steps to testing your material in our article about Test Washing Cannabis for Hash Production. 

#11 Green hash could mean you’re mixing too aggressively
If the resin you’re collecting from the filters takes on an emerald hue, that’s a sure sign of excess plant material that’s working its way through the screens along with the trichome heads. The main cause of plant matter getting through the screens is overly aggressive agitation while mixing the cannabis material and the ice water. If the hash is green, go easier on the mixing. Hash can also start to turn green after multiple washes of the same material, a sign that it’s time to retire that material and mix a fresh batch.

#12 For the first couple of washes, go easy on the material
To thoroughly extract all resin from cannabis material, it’s necessary to give the material multiple rounds of washes. Be gentle with the first couple rounds of mixing. You’ll get the maximum number of trichomes to release with the minimum amount of plant material coming along with it. With subsequent rounds of mixing during the wash, you can agitate/mix more vigorously to encourage the remaining resin to fully release from the material.

#13 Pre soak the cannabis 
Whether you’re using fresh frozen or air cured cannabis, it’s important to pre-soak the material in the ice water for 20-30 mins before beginning the wash. This prepares the material to release its resin and prevents against pulverizing the plant matter which can end up in the hash.

#14 Use high quality hash washing bags
Low quality hash washing bags will let you down and potentially leave fibers and/or tiny pieces of plastic in your hash. It’s also a good practice to wash the bags in clean water before using them for the first time. Also, bags that incorporate screens extending a couple of inches vertically into the sidewalls allow for faster water drainage, saving you processing time and reducing strain on your back. The Press Club makes premium wash bags for hashishins who aim for quality above all else. 

#15 Spray the sides of the wash bags before collecting hash
After the water has been poured through the bags and the hash has pooled into the center of the filter screens, there are still some trichome heads that have stuck along the sidewalls of the bags and outer edges of the filter. Use cold, clean water in a sprayer to rinse all trichomes down the sidewalls and into the center of the filter screens for easy, thorough collection.

#16 Modify 5-gallon buckets to make a convenient stacking system
Cutting away the lower section of 5-gallon buckets, leaving just a 6-inch ring of plastic around the top, makes for a great stackable system when washing hash. Rather than stacking each wash bag by itself, one inside of the next, you can use the top portion of a plastic bucket to hold each bag. With each bag in the set of wash bags having its own plastic ring upon which it hangs, you can then stack the plastic rings with the bags inside of the main work bucket. This makes for a more efficient set up, mostly because it’s easier to lift and drain each bag by holding onto the plastic ring. We wrote a whole article about How To Set Up Your Hash Bucket Mod

For draining water from the bags, you can even suspend the bags by securing a pulley system around the plastic rings, taking all the strain off of your back. Remember to remove the metal handle from the top of the bucket before putting it to use. Check out other ways to reduce strain on your back in our article How To Reduce Stress on Your Back While Washing Hash. 

#17 Don’t use corrugated drainage hoses on washing machines
Corrugated drainage hoses have ribs along the entire inner surface of the hose, which creates traps for your trichomes. Trichomes will get stuck and accumulate inside the corrugated hose instead of draining into your wash bucket for collection. When using a washing machine for hash production, be sure to install a smooth drainage hose and ditch the corrugated hoses. 

#18 Keep your metal collection spoon in the freezer between uses
An ice-cold spoon is a great tool for collecting resin from your hash washing bag filters. But if the spoon warms, even to a cool room temperature, it's likely to begin melting hash as you work it across the screen to scrape up the resin. Once a little bit of resin starts to collect on the edge of the spoon, it's game over. This bit of resin will accumulate more and more resin. To help prevent this, keep the spoon in the freezer until it's ready for use. 

#19 Stretch filter screens over a plate or frisbee for collection
It can be tricky to reach down inside the bag for the hash that's pooled into the center of the filter screen. The filters often sink into a cone shape, presenting some challenges when you're trying to collect hash at the narrow tip of the cone. To avoid this situation, just place a plate or a frisbee underneath the filter in order to maintain it's round, taut form. Then wrap the sides of the bag around the edge of the plate and you can easily access the layer of hash that's collected at the top of the filter. 

#20 Put wet hash in the freezer for 24 hours before sieving  
When hash is collected from the hash washing filters immediately after extraction, it's in a gooey, viscous, gelatinous form that is very difficult to handle. This sticky puddle of wet resin can't be worked through a sieve in its current form, but some time in the freezer will solve the issue. Place the wet hash on some parchment paper-lined cardboard, and leave it in the freezer for a full 24 hours. Once it's frozen into a hard mass, it's ready to pass through the sieve for thorough drying. 

Conclusion

As much as science plays into the ice water extraction method of washing hash, solventless extraction is more of an art than a science. So while there are basic guidelines to follow, and surefire tips to keep in mind along the way, it’s the extractor’s ability to sense and respond to the cannabis plant and its trichomes that matters most. It’s best to feel your way through the process with an open mind and willingness to experiment. Even failure isn’t failure if you’re learning along the way. 

FREQUENTLY ASKED QUESTIONS

What is “Dumping”?
A cannabis cultivar is said to "dump" when it produces copious amounts of capitate-stalked trichomes that release easily during the ice water extraction method of producing bubble hash. The best cannabis strains to use for hash production are known dumpers. Check out our article about which cannabis strains are known to dump.

What kind of work bucket should I use?
Plastic 5-gallon buckets work great if you’re using a 5-gallon hash washing bag kit. Be sure the buckets are clean. Stainless steel is also great material for a work bucket. The size of the work bucket should match the size of the hash washing bags. 

Where should I wash the hash?
Wash the hash in a room that’s cool enough to maintain cold temperatures of your water and equipment. You can even set up an entire room for washing hash. See our Guide To Building the Ultimate Hash Washing Room.

How do you store hash after it’s been thoroughly dried?
Storing hash in sealed glass jars in a cool, dark, dry environment is best for long-term storage. Some people like to keep hash stored in the refrigerator or freezer, to slow down the natural process of degradation. If storing in the refrigerator or freezer, be sure to let the hash come back to room temperature before cracking open the top once you take it out for use. And then wipe away any condensation on the inside edge that may form. Avoid moisture in your hash!

Should I mix the cannabis and ice water by hand or with a washing machine?
Both methods of mixing are effective, but we prefer hand washing for the amount of control it gives. Be sure to use a metal or plastic spoon or paddle, not wooden. See our article about Hand Washing vs Machine Washing for more info.