How Bubble Hash is Rated (1* to 6*)

There aren't too many sights and aromas in cannabis that compare to the tiny bubbles that form when dabbing full melt bubble hash. We may not always take notice because we're smoking the delicious concentrates, but those tiny bubbles (and specifically how nothing should be left when they're gone) let you know that you're consuming the highest quality product around.

Bubble hash represents some of the best in solventless cannabis today. That is why rosin pressers love using it for their extractions. However, not all strains are created equal. Not every strain can cut the mustard because how it was grown, the strength of the genetics, the intrinsic terpene profile, and more all play significant roles. Even when strains are capable of producing full melt, the chances of making elite bubble hash can leave even some of the top names in the game scratching their heads. That said, they and aspiring solventless extractors in companies and home operations alike push forward to reach the upper echelon in the category.

To reach this level yourself, here is what you’ll need to look out for when creating your own ice water bubble hash and how it becomes the best.

How Bubble Hash is Rated

With the rapid expansion of cannabis offerings, hash producers and other businesses in the supply chain developed a system for rating products. The one to six-star rating system helps establish a precise pecking order and criteria for what it takes to reach the tops in dry sifting, kief, bubble hash / ice water extracts. However, joining the ranks of the best takes hard work and, most importantly, terrific starting material. Thank your grower if she or he is killing it!

1 and 2 Star

At the low end of the spectrum is where you’ll find dry sift or hash that is full of contaminants and which is far less than ideal for melting. 1 to 2 star is usually less than even half true trichome heads and stalks, with the rest typically being various organic detritus. However, these one and two-star hashes do work well for edibles - giving it the distinction "food grade hash." In addition to edibles, they are well known for being a potent addition to smoking any flower and is the most affordable kind on the market. These days you don't see much if any 1 or 2 star on any shelves, anywhere.

3 and 4 Star

Known to many as "half melt", 3 and 4 star hash or kief does just that, it half melts. The reason for the half melt is due to the presence of some debris and plant material in the final product, however it is considerably less than 1 or 2 star. These can include tiny bits of leaf material and anything that isn't a full trichome head or stalk. Half melt adds potency to smoked flower products as a bowl topper but is more often than not pressed into rosin. Half melt does works for dabbing as well, but it should usually be pressed into rosin for the best results.

5 and 6 Star

With virtually only the trichome heads and stalks remaining, 5 and 6 star bubble hash should be free of all contaminants and residue. This is the best of the best. Many claims of 5 and 6 star are actually 3 or 4 star, in our experience. True, top tier bubble hash should leave you with a copious amount of cannabinoids with a robust terpene profile to boot. It also comes with high potency test results and a trying process to perfect - which can often lead to high sales prices that are entirely deserved. With such an enjoyable product and the market demand, producers have entered the space at a rising rate in recent years. The key difference between 5 star and true 6 star is that 6 star should leave absolutely no residue on the dabber or nail when vaporized, hence the name "full melt". These grades of hash are typically only drawn from the 90 and 73 micron range, but can occur at 120 as well in certain cases.

Reaching a true 6-star caliber can be difficult, but with the right material and processes it becomes much more reliable. 5 star tends to be much easier to produce if you consistently have very high quality material but are still perfecting your wash and dry processes. Creating an elite full melt hash goes beyond the need for quality flower and know-how.

A Quick Note on Full Spectrum

Often, concentrates, oils, and bubble hash are emphatically referred to as "full spectrum". Full spectrum means that the product contains a variety of different cannabinoids and terpenes, thus encouraging the entourage effect as well as providing a much higher quality product overall. All good bubble hash is full spectrum, as opposed to distillate or other mono-cannabinoid/terpene concentrates.

What Does Bubbleman Have to Say About It?

We reached out to the godfather of the process himself to get some clarification - MarcusBubblemanRichardson enlightened us with the following:

When trying to figure out the quality of bubble hash, we generally have the star system that accords to melt factor. Remember, oil always melts, but micro-encapsulated resin glands do not always melt. The melt factor is one of the main ways we decide what the quality of the resin actually is. 6 star being the highest of the high, melting into a liquid dropping down, not puffing up like a volcano, but falling into the surface area of what you are smoking off of. It will also pop up large clear domes. I would say 6 star is not only full melt but it's when you have a full melt, clear dome trichome head. When you have bubble hash of this quality you may see up to 90% returns on rosin, but it’s actually very rare.”

In addition to bubble hash, a similar rating system for dry sift and kief has been informally created. The criteria for ranking the materials is close to bubble hash's guidelines and can have you producing near full melt concentrates as well. However, it should be noted that creating full melt dry sift is not as easy as throwing trim in a sifter. Many mistakenly use dry ice, which rips open the trichome heads and stalks of the flower. This instantly reduces the quality of the final product dramatically. Very delicate sifting, without dry ice or only with very small rice-grain sized dry ice pellets, is necessary to produce light colored rosin.

Bubble Hash 6 Star Full Melt from Essential Extracts Tigers Milk

How to Tell the Quality of a Melt

There are a few steps to take in order to determine the quality of your hash.

  1. How transparent are the resin glands after they have been at room temperature for at least a few hours?
  2. Using a high definition microscope, what is the ratio of intact, full trichome heads versus stalks?
  3. How clean is the hash overall? It should not contain debris such as dirt specs, microfibers, or plant matter.
  4. Using a quartz nail if possible, do a melt test and see how much char is left on the nail. 

If your bubble hash is free of debris, is composed of entirely or almost entirely intact trichome heads, and leaves zero residue on a quartz nail, you have nailed it - that's full melt. If it doesn't meet these criteria, it will fall somewhere else on the spectrum.

What Strain is Your Hash?

There is no way around it. If you use a subpar strain, you are going to end up with a subpar bubble hash. Look for a flower that is rich with terpenes and looking like it is covered in crystals. Certain terpenes however do not wash very well, which largely depends on phenotype. Often, strains that have a Chem lineage do especially well for washing. If you want to learn more about great strains to wash, check out Ed Rosenthal's guide on some of the best ones here.

Look and Smell

The look and smell of your bubble hash is just as critical as it is to the flower itself. The look of your hash should turn from the more golden yellow color to a slightly darker hue with a slight transparency when left in moderate to warmer temperatures. It will also become sticky as it "greases" up into a less pliable consistency. In order to properly store premium bubble hash, it should be placed in an airtight and moisture-tight container in the freezer. 

If you notice any signs of green, brown, or black, however, then you have a problem with your process. Alternatively, if your final product has noticeable trichomes, then you’re in business with quality bubble hash.

In order to achieve the best result during the drying process, which is typically the most difficult part, modern hash makers all use freeze dryers. A freeze dryer dramatically helps in terms of increasing clarity and increasing consistency into the process. Whereas air drying can take a week or more in a carefully controlled environment, a freeze dryer typically only takes 24 hours or less to get a perfectly dried consistency. Freeze dryers are worth every penny for anyone trying to consistently produce high quality bubble hash.


Like its appearance, your bubble hash should smell like the strain you started with. This ensures that your bubble hash maintained its trichomes and aromatic profile. If you notice a lack of your starting fragrance, then you should reassess your process or consider trying different techniques.

The PurePressure Method for Bubble Hash

In past articles, we've detailed how we at PurePressure go about making our bubble hash. We typically recommend spending the extra money to get an 8 bag Bubblebag kit in order to capture as wide of a variety of trichome head sizes as possible.

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Here is how it generally works out, but every strain is different and trichomes come in many different sizes. Most often 73 and 90 micron are the very best, but it really just depends on the plant.

-25 micron bag (low to medium quality trichomes)

-45 micron bag (medium quality trichomes)

-73 micron bag (high quality trichomes)

-90 micron bag (typically the best quality trichomes)

-120 micron bag (high quality trichomes)

-160 micron bag (low quality trichomes)

-190 micron bag (often debris being filtered out)

-220 micron bag (often debris being filtered out)

From there, we agitate the flower in a freezing ice washer inside a cold room for roughly five minutes per cycle. When filling your machine with water, be sure to use reverse osmosis purified water. From there, your bags come into play as the separated trichome heads are then strained and drained through your bags. We then rinse the bags while inside the washer but outside of the ice. From there, the bags are entirely removed, separated and slightly rinsed before scooping out the final product for freezing.

Everyone makes ice water hash differently, and you can certainly deviate with your own methods at points in production. Our process resembles what top names in bubble hash use as a general standard. If you decide to choose this route, it is vital that you use only the finest flower. As we mentioned previously, you have no chance of producing full melt with an ill-fitting strain. Remember that even some of the top strains don't do the job for generating bubble hash.

Beyond your flower, your water can make or break the process as well. Freezing cold purified water is the way to go. Ice water helps separate your trichome heads by freezing and snapping the stalks and heads from your buds. By using filtered water, you eliminate the risk of developing a chlorine taste or introducing any undesirable contaminants.

Lastly, we wholeheartedly endorse considering a freeze dryer as it takes the headache and inconsistency out of drying bubble hash, not to mention it dramatically can help increase "bag appeal" and clarity. Freeze dryers cut down on drying and processing time immensely, saving you hours and possibly days. Instead of complicated air drying, a freeze dryer simplifies the process like no other can achieve.

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When sourcing bubble hash for yourself, consider the above factors. Whether making or purchasing the product, be on the lookout for what and how the bubble hash was produced. From the choice in strain to the room temperature it cooled in, each factor can alter the outcome of your bubble hash. That said, remember the difficulties associated with generating 5 and 6-star bubble hash. Don’t get discouraged if you stumble out of the gates. By adhering to these guidelines, you are likely to produce quality half melt hash, at least, while striving for the goal of full melt hash.