What Do Micron Ratings Mean for Hash and Rosin?

Eric Vlosky
Last Updated at
1:22 pm
June 14, 2024

If you enjoy solventless extracts and concentrates, you’ve undoubtedly come across things on product labels such as “90​​μ - 120​​μ” or the denotation “Mixed Micron” for rosin or ice water hash, aka bubble hash. Micron ratings, their numbers, and their symbols (u, ​​μ, and μm) all represent one of the two accepted grading systems for trichomes in solventless extraction. The other is the still subjective star rating criteria, which we’ll get to in a moment. A lot of people we speak to who dab often still aren’t completely clear on the matter, so we figured it’s time to clear the smoke to explain what these terms mean and why every consumer should get educated on microns in cannabis. 

Cannabis and hemp plants grow what are known as trichomes in different shapes, sizes, and types depending on many factors. They’re the tiny vessels that contain the majority of the plant’s cannabinoids and terpenes alongside many other beneficial organic compounds. That’s what full spectrum means in a nutshell. Even the biggest ones however are still tiny and barely visible with the naked eye, if at all. While there is already a ton of excellent information you can easily access on the internet about every eye watering detail on them, hash micron ratings and what they mean for connoisseurs is another matter. 

A 140μm trichome macro image, image courtesy of Shwale and Farmhouse Studio

What Is a Trichome Micron Rating?

Simply put, a micron is a unit of measurement, specifically related to the size of tiny objects. A micron is technically defined as one millionth of a meter, which is abbreviated as μm. Well, you might be asking, why did you list three separate symbols above then? That’s because depending on the brand, you will probably run into all of them in your rosin and hash adventures, but they all basically mean the same thing. μ is the special symbol for one millionth (10−6), and for those who get lazy or who knows why, “u” is also commonly used instead of these other special characters. μm would perhaps be the most accurate but it really doesn’t matter as long as you know what you’re looking at. 

Cannabis trichomes typically range in micron size from 180μm to smaller than 25μm, with the very best being known as capitate stalked trichomes in the 90μm to 120μm range, or sometimes slightly higher into the 140s. To put these numbers into perspective, a human hair is typically 70 micrometers across whereas white blood cells are 25μm or so. That’s pretty small. The juiciest trichomes are about two hair widths wide, and the smallest ones can be as tiny as red blood cells. It’s a lot easier to see what you’re working with using an inexpensive jeweler's loupe, or if you want something a little more advanced, check out our preferred yet still affordable 1,000x magnification digital microscope.

Micron designations are especially important for bubble hash because it’s just aggregated, dried trichomes, but are also a useful marketing tool for hashmakers to showcase when their finest resin is being used for a particular batch of rosin, too. They determine micron size by filtering bubble hash or dry sift through a stack of variously woven polyester or stainless steel screens that have been manufactured in different sizes. As many as 8 are used at once so that wet ice water hash can be effectively graded early in the process before it’s dried. 

A macro shot of gently flattened 6 star ice water hash trichomes, image courtesy of Boro.Vision

Why Micron Ratings Matter 

So you might be wondering at this point, yeah so what trichomes come in different sizes, who cares? Does it really matter? In fact it does, and quite a bit. Artisan solventless extractors that have worked with countless strains and metric tons of cannabis will tell you that there is a middle band in the trichome micron range for most cuts that tend to be the most resinous, high quality selections. It does vary quite a bit however from strain to strain, and even from phenotype to phenotype of the same strain. It’s also the subject of some debate, as many purists deliberately try to find hash or rosin that they know was made from those prime trichomes in the 90 to 120 size range. 

That can be a limiting way to select your hash however, as most live rosin these days is made with a blend of microns spanning most of what the plant produces. In almost all cases, anything between 70μm and 140μm on the majority of well grown strains is likely to produce something worth trying. It’s on the ends of the spectrum where quality tends to drop off, as pretty much anything below 25 micron is often set aside as “food grade” for edibles, topicals, or tinctures and above 140 you tend to have not had enough filtration so other inert, organic plant debris is often present in higher quantities alongside the trichomes when viewed under a microscope. 

Whenever you see the words “Mixed Micron” on a label, that means the hash makers used many different sized trichomes to make your product, which isn’t necessarily a bad thing but does often mean medium quality as opposed to their true A grade stuff. That’s most often going to be 45 all the way through 140 mixed together. It’s also equally common for top shelf rosin to be “90μ” or “120μ”, which means it was pressed with only that size of trichome and is aiming to provide some of their best. These micron ratings, when combined with the star system, give you a full picture of possible quality of hash or rosin you could purchase.

What the Hash Star Rating System Means

In conjunction with micron sizes, many hash makers also will talk about the star rating of the hash they used to make their rosin, or if it’s full melt bubble hash, that it’s true six star. Ice water hash is semi subjectively graded on a one to six star scale, with one being barely food grade and six being super rare, legitimately primo stuff. The reason for the semi caveat is that as you can read in the article linked above, six star hash needs to be ultra clean and fully melt to qualify, while five star material (which is still excellent ice water hash) tends to be a little less perfect. 

It’s extremely rare that six star is present outside of the 90 to 140 micron range, with the majority of it coming in closer to that often repeated 90 to 120 sizing instead. If you ever see rosin or bubble hash being labeled as full melt mixed micron, you can rest assured they don’t know exactly what they’re talking about because only in that narrow micron band are you going to find five or six star hash that’s worthy of top dollar pricing. 

How to Understand Micron Ratings to Buy the Best Hash

What all of this comes down to is better navigation of solventless concentrate purchases based on your desired quality and price point. Premium micron rated rosin is pretty much always going to cost more and rightfully so. If you’re after a more economically priced solventless gram, try to find mixed micron products or brands that are known for quality without inflated costs. Here are the most helpful ways to think about all of this as a mental note to jot down the next time you’re shopping for solventless:

#1: The best hash and rosin is made with five or better yet six star ice water hash, which is almost always made from trichomes that are between 90μm and 120μm in size.

#2: Six star full melt ice water hash is rarely if ever made with anything below 70μm or above 140μm. This is your A5 wagyu beef, and it should always be kept in a cold environment, especially if you’re traveling (check out these handy portable insulin coolers for that purpose). 

#3: Mixed micron isn’t a bad thing, but the price point of the hash or rosin should reflect a more budget-friendly offering.

#4: Most hash makers will use their best trichomes for their top shelf rosin and will set aside the highest and lowest microns for edibles. 

The next time you go to the dispensary or are shopping for drops online, keep an eye out for microns so you can find that next jar of solventless exactly to your liking. Just remember though, microns aren’t everything, and many brands won’t always tell you which they used for any given batch. That’s OK in our book as experimentation is the only way to find out on a personal level which quality tier fits your budget and taste preferences.

We'd like to give a special shout out to Shwale of Farmhouse Studio for permitting us to use all of the imagery used in this blog article. You should definitely check out their genetics and their work!

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