📌What Is the Purpose of Using Different Micron Bubble Wash Bags for Ice Water Extraction?

Todde Philips   

🇺🇸 Retired veteran, father, rock-climbing expert & rosin connoisseur

Bubble wash bags are the central piece of gear used in the ice water extraction process, a solventless method of making bubble hash. Bubble wash bags are made from food-grade, special non-stretch materials that fit inside of a bucket and stack one inside of the other, secured along the top rim of the bucket. Wash bags are made in various sizes to accommodate different amounts of cannabis material. The most common sizes of bags are 5-gallon for in-home use and 32 or 44-gallon for commercial use. We have 10-gallon, 20-Gallon and 65-Gallons available too. 

Bubble wash bags are made with different size filters, or mesh screens, at the bottom of the bag. These screens act as sieves to isolate the cannabis plants’ resin-filled trichomes from the remaining material. Bubble wash bags are sold in kits of 4 or 8 bags. You can also purchase individual bags from companies such as The Press Club. 

After cannabis is mixed thoroughly with ice water the cannabis material releases its trichomes, which remain floating around in the slurry. Then the cannabis-infused ice water is poured through the series of bubble wash bags stacked one inside the next. 

The purpose of using multiple wash bags is to provide varying degrees of filtration, offering an array of different grades of hash from the filters. 

Learn the full process of how to wash hash in our article How to Wash Bubble Hash.




How Bubble Wash Bags Work


Screen size determines the filtration capability based on the pores within its mesh filter. Pores in the screens are measured in microns. Larger pores allow larger pieces of material to pass through, while smaller pore sizes allow only small pieces of material to pass. On top of each screen there is a collection of material that’s too big to pass through the screen. 



When ice water and cannabis material is mixed together, trichome heads break free from the plant material and float around in the water. But trichome heads aren’t the only thing that breaks free in the water. Trichome stalks and tiny pieces of plant material also come loose and need to be filtered out. Without this filtration, contaminants will end up in the finished product. 

What collects on top of each screen is hash in one grade or another. Hash that’s almost exclusively whole trichome heads without the stalks is the highest grade of hash. The lowest grade of hash includes only partial trichome heads, pieces of stalks, and tiny plant material. 

The highest quality of hash includes almost exclusively whole mature trichome heads. Therefore, a wash bag with a screen that most closely matches the diameter of trichome heads will collect the highest grade of hash.

Here’s a breakdown of the various filter sizes included in an 8-bag kit:

220 micron: Main work bag
This bag has the widest pores and therefore allows the largest size of material to pass through. Trichome heads, trichome stalks, and small pieces of plant material are all able to pass through this screen. Larger pieces of plant material are caught in the filter, which provides the first level of filtration after ice water is mixed with cannabis. The material that collects in the main work bag isn’t worth keeping, due to low quality.

190 micron: Clean-up bag
The 190-micron bubble wash bag is the next level of filtration, pulling out more plant material as the ice water slurry passes through. Trichome heads are small enough to pass through this screen, so none of the material that collects on this screen is generally worth keeping. This bag provides extra refinement, but nothing for collection.

160 micron: Contaminant removal bag (food grade/low quality)
This bag filters even smaller pieces of contamination out of the water, but also allows most full trichome heads to pass through. However, there  will still be trichomes, and trichome stalks, that get trapped in this filter. The hash that collects here won’t be high quality, rather food-grade which is in the 1-2-star range for rating hash. But for edibles, this screen can be worth collecting. 

120 micron: Trichome collection bag (great quality)
This is the first bag that will yield some noteworthy hash. The previous filters capture the large pieces of plant material, so most of that has already been sieved from the water. What is left on the top of the 120-micron screen is trichome heads (and often the connected stalks) and some minor contamination. 


90 micron: Trichome collection bag (excellent quality)
Some of the best hash that you’ll get can be taken from the 90-micron bag. This size of filter closely matches the size of full mature trichome heads, not including stalks. There won’t be much plant contamination left on this screen either. 

73 micron: Trichome collection bag (premium quality)

The 73-micron bag will collect the highest grade of hash, because it most closely matches the size of full, mature, unbroken trichome heads without stalks. Very little plant contamination should be collected in this filter, as the majority should have already been filtered out of the water by previous screens. 

45 micron: Trichome collection bag (large yield secondary grade)
Most of the full trichome heads that make up premium hash have already been filtered out of the water, but partial heads and stalks will still collect on this filter. The quality isn’t great, but it’s still worth keeping for edibles or to mix with flower for smoking. 

25 micron: Trichome collection bag (food grade/low quality)
This last and finest filter will contain a grade of hash that might work for making edibles, but often the quality isn’t good enough to dab by itself or even press into rosin. Some extractors pitch the material collected on this filter, but as always you should experiment with your cultivar and see what you can get. 




Should I Use 8-bag or 4-bag Bubble Wash Bag Kits?

8-bag kits always provide a broader range of filtration and therefore more grades of hash to choose from. Cultivars you’re washing for the first time should be filtered through all 8 bags. This gives you the chance to see which of the filters will most closely match the trichome heads you’re washing, which will be the bag that collects the highest grade of hash. If you only use 4 bags, you may miss that filter size (for example the 90-micron) that best matches the size of trichome heads. And while the range is generally the same, different cultivars produce different sizes of trichomes.

After you’re more familiar with the way your cultivar washes and identify which micron size collects the highest grade of hash, you can reduce the number of bags you wash with. But 8 bags will always give you the best filtration control. 


Collecting fine grades of hash requires multiple filters. Larger filters catch large plant contaminants, getting smaller and smaller until they closely resemble full mature trichome heads. The filter that is closest to the size of trichomes will yield the highest quality of bubble hash. 

If only one or two filter bags are used, there would be limited filtration opportunity and therefore trichome stalks and other plant contamination will be mixed with the trichome heads, lessening the quality of the hash. Multiple bubble wash bags provide the most desirable refinement, and 8-bag kits offer the most control and refinement for extractors during ice water extraction. 



What is the best micron wash bag?
The 120, 90, and 73-micron bags provide the highest grades of hash.

Do you need an 8-bag kit?
8-bag kits are ideal when you’re first working with a new cultivar, to help you gauge the size of trichome heads and find out which filters will yield the highest grade of hash.

What microns are included in an 8-bag kit?
220 Micron, 190 Micron, 160 Micron, 120 Micron, 90 Micron, 73 Micron, 50 Micron, 25 Micron

What microns are included in a 4-bag kit?
220 Micron, 160 Micron, 73 Micron, 25 Micron

Can I use only 1 or 2 bags to wash hash?
Technically you can, but the resulting hash will likely be full of contaminants. Washing with just 1 or 2 bags will not provide the filtration power needed to produce premium hash.



1 comment


Beginner here
Do you just scrape the trichomes off the screen ? Then press/mold ?

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