Pressing Rosin Bags Forward: The Evolution of PurePacks

Commanding high prices, rosin is a key product in mature cannabis markets and the purity of the final extract is key. For solventless extractors, rosin bags are a ubiquitous consumable, with extraction technicians at commercial operations using 2,000 bags a month when pressing. Working at such rates, hand flipping bags, double bagging, adjusting slipped bags, and dealing with blow outs wastes time and resources.

PurePacks Rosin Bags

Prepping PurePacks to be pressed at Olio in Denver, CO  

While rosin bags are not the most valuable pieces of equipment in an extraction lab, their usage and number mean they have a direct effect on efficiency and yields.

Material Considerations

Material for rosin bags is historically contentious, the great battle of polyester versus nylon. PurePressure’s first rosin bags were made from polyester due to the materials’ rigidity and ability to hold a micron rating under pressure. However, polyester is more brittle than nylon under pressure and, as the industry matured, customers expressed a preference for the less costly and easier to use nylon. PurePressure delivered, pivoting to nylon bags like the rest of the market. These nylon bags were the first rosin bags to receive an FDA certification as well as undergo third party migration testing.

Unlike polyester, nylon stretches. This reduces blow outs, as the fibers stretch to give way to pressure. However, when stretched, the weave of the fabric changes, thereby changing the micron rating of the bag. Losing the integrity of the weave means the material in each bag is being pressed through a different micron rating, causing inconsistencies in the extracted rosin.

 PurePressure nylon Rosin Bag (L) and NEW PurePacks polyester Rosin Bag (R)

PurePressure nylon Rosin Bag (L) and NEW PurePacks polyester Rosin Bag (R)

With a focus on consistency, PurePressure’s newest rosin bags, PurePacks, are made from polyester. Polyester holds a tighter tolerance, meaning consistent micron ratings, and is reinforced, equating to a more consistent product with fewer ruptures when properly used. 

Reinforced, Stitchless Design

Our customers find that double bagging, especially stacking differently sized bags, leads to increased yields. PurePressure tests revealed that two finer filters of the same micron size restricts flow, whereas a smaller micron filter with a larger filter on top increases yield and reduces slipping.

The fibers in a larger, 120 micron bag are both bigger and spaced further apart than fibers in a 25 micron bag. This means more friction between the filter media and parchment or PTFE sheets, leading to less bag sliding. 

PurePacks double layer filtration Rosin Bags

PurePacks double layer filtration Rosin Bags

Traditionally, rosin bags are sewn. In addition to the obvious nuisances such as stray threads, fraying edges, and the need to turn bags inside out, the seams themselves can be an issue. A weak point that can be prone to blowing out, both the size of stitches and the size of the sewing needle compromise the micron size of the bag.

Stitchless, sonic-welded edges on PurePacks Rosin Bags

PurePacks utilize sonic welds rather than traditional stitching, with the welded seam placed on top of the bag. This placement creates a full perimeter of mesh for filtration, reduces blow out rates along seams, reinforces seams to prevent ruptures if used as intended, means less back slipping, and ensures filtration media has a more reliable micron rating. Additionally, the stitchless process works better on polyester than nylon, reinforcing PurePacks’ material choice.

Rigorous Testing & Customer Feedback

Talk to anyone pressing rosin using any bag and you’ll hear frustrations with flipping, fraying, and double bagging. PurePressure product designers compiled these complaints and more to build out their requirements for a new bag and set out to design a bag that addressed each. The result? PurePacks.

"Achieving the highest quality solventless rosin is always front and center for me. For the time spent flipping bags alone, PurePacks are time savers that directly improve my ROI and allow me to produce the highest quality product." 

- Collin Palmer, CEO, Vessel Life Science

"At the end of the day, it's saving labor. The efficiency of not double bagging...if you're pressing all day, you're going to cut out that quarter of your day you spend preparing."

- Sebastian Marquez, Lab Director

After trial, error, development, and troubleshooting, the resulting PurePacks were sent to industry leaders for rigorous testing and further refinement. PurePacks therefore represent extensive research and development, all approved by industry experts, who reported increased yields of 4-5%, less bag absorption of rosin, zero bag ruptures, less wicking, and convenience of use—even from those who were initially skeptic!

These responses led us to offer a zero blow out guarantee: if properly packed, PurePacks are guaranteed to be blow out free or we’ll send a replacement—no questions asked.


PurePacks are PurePressure’s third rosin bag release, the result of years of R&D and, more importantly, a response to customer feedback. With the release of PurePacks, PurePressure is the only company in the industry to offer a stitchless double bag you don’t have to flip. Are you ready to put double filtration, sonic welded polyester rosin bags to the test? Try PurePacks today!