Pre-Roll Master Class: Part II – Grinding and Sifting Fundamentals

Welcome back to the Custom Cones USA Pre-Rolls Expert Master Class where we are covering the fundamentals, as well as tips and tricks, of creating high-quality pre-rolls at scale.

We’ve spent years studying what goes into making perfect pre-rolls and our mission is to revolutionize and enhance pre-roll products by setting a benchmark for excellence and innovation in the industry by sharing that knowledge.

In Part I, we covered Paper Science 101, looking at the basics and science of what goes into making the rolling papers that make pre-rolled cones.

Now that we talked about the paper, let’s talk about packing your pre-rolls.

When creating high-quality pre-rolls, we like to say it all starts with the grind.

Properly grinding your cannabis flower is not just another step in the production process — it’s a foundational piece that can make or break the quality of pre-rolls.

Poorly ground cannabis leads to inconsistent particle size, which can lead to gaps inside the cone, resulting in pre-rolls that run or “canoe” due to disrupted airflow. This not only affects the smoking experience but also impacts the potency that customers can expect from your product.

A poor grind also leaves you with chunks that can wreak havoc on pre-roll machines. These larger particles make it difficult to produce consistent, evenly packed pre-rolled cones and tubes, which can ultimately hurt your bottom line.

Particle size also influences the efficiency of cannabinoid and terpene extraction during smoking. Smaller particles provide greater pack density and surface area in pre-rolls, allowing for more effective extraction and enhanced potency when consumed.

What to Look for in a Cannabis Grinder

Since the main purpose of grinding is simply breaking down cannabis flower to a usable size, pre-roll companies use a variety of choices on how to make that happen, ranging from household appliances like blenders and coffee grinders to whip-style machines and shredders that tear apart the cannabis to industrial grinders designed specifically for pre-roll manufacturing.

However, the two most important things to look for when choosing a machine to breakdown cannabis are RPM and torque. The RPM, or Rotations per Minute, and torque of your grinder play a pivotal role in preserving the quality and integrity of your flower.

Whereas kitchen machinery and shredders us high RPMs to tear apart the flower, high-quality cannabis grinders typically use low-RPM motors that operate at slower speeds. The key difference is in the amount of heat each machine generates.

High RPM machines generate a lot of heat, which can damage the trichomes on your flower. Trichomes, of course, are the structures that house the cannabinoids and terpenes, so any damage to those can leave you with less potent, less flavorful cannabis.

Maintaining a low temperature throughout the grind helps preserve the natural profile of the flower, resulting in pre-rolls with robust and nuanced flavors that reflect the original strain characteristics. This also helps improve the overall consistency and quality of the ground material, which often becomes dry or brittle due to excess heat.

A high-torque, low RPM grinder, on the other hand, like the Industrial Cannabis Grinder, generates much less heat while still breaking down pounds of sticky flower into a smaller, more usable size, protecting the trichomes in the process. And that means more flavor and more potency in your pre-rolls, not your grinder.

Despite this, about 26% of pre-roll businesses still use basic machinery like blenders, food processors, or shredders, despite the damage they can do to the flower.

A high torque motor can also more efficiently break down tougher material than a high RPM motor, resulting in a consistent grind that has minimal stress on the flower and is better for use in cone-filling machines during the next steps of the process.

The Importance of Sifting

Because particle size of cannabis is one of the biggest factors in the overall quality and performance of your pre-rolls, consistency is key.

Following grinding is the often overlooked, but crucial step of sifting. Sifting not only helps further ensure a consistent particle size, but also removes any stems that get through the grinder, along with any other foreign material or large particles that might tear or break your cones when you go to fill them.

It's a simple step, but if overlooked it can lead to uneven, broken and overall poor-quality pre-rolls.

Scientists who studied the effect of particle properties on the flowability of ibuprofen powders found that, for powders with a narrow size distribution, the flowability increases significantly with the increase in particle size. Sifting allows further control over particle size, so you can create what is known as a free-flowing powder, which will allow you to make pre-rolls that are well packed throughout from crutch to tip.

In fact, not only will you make better pre-rolls, but you will make more pre-rolls faster.

Sifting for a Better Packed Pre-Roll

At Custom Cones USA, we have conducted our own experiments, running both sifted and un-sifted material through one of our popular cone-filling machines. With un-sifted material, the weight variance of the completed pre-rolls was 65% higher than the sifted material. The number of pre-rolls that had a hole due to stems was 488% higher than the sifted material. And the number of pre-rolls with an unsatisfactory pack was 194% higher than the un-sifted material.

Put into real world numbers, that means out of a run of 169 pre-rolls, you will get 27 more usable pre-rolls when you use sifted material versus un-sifted material. When you think about what that means cost-wise for your production the value of a sifter becomes clear.

Sifting is even more important when using an automated pre-roll filling machine, because consistent particle size is a necessity to keep things moving. Some machines even require an exact size to work properly.

Beyond the speed, consistent particle sizes lead to better-packed pre-rolls. And better packed pre-rolls are better smoking pre-rolls.

This is because different sized bud particles burn at different rates, with smaller particles burning hotter and faster than larger ones. Different particles sizes also prevent smooth airflow through the pre-roll and can lead to uneven packing or gaps inside the pre-roll. All of these can lead the pre-roll to canoe or run, burning unevenly down one side of the cone.

Finally, sifting for a consistent particle size makes it easier to use a volumetric metering tray to help speed up the production process, which we’ll get into in the next part of this series.

But for now, just remember that particle size and particle distribution have a scientifically proven impact on the flowability of air through the pre-roll, which in part determines how the pre-roll burns. And as our experiment found, it also factors into the speed with which you can produce pre-rolls.

Next, in Part III, we’ll get into the Best Manufacturing Practices for Pre-Rolls.