Mastering the Stack: The Definitive Guide to CRC Filtration Media for Cannabis Extraction

Optimizing Color Remediation Chromatography in Cannabis Extraction

Color Remediation Chromatography (CRC) is a specialized filtration process used to remove impurities—such as chlorophyll, pheophytin, carotenoids, and pesticides—from botanical extracts. By leveraging the principles of adsorption, extractors can achieve superior clarity and shelf stability.

Effective CRC relies on the strategic layering of media based on their polarity, pH, and particle size.

1. Polar Filtration Media: The Primary Separators

Polar media are typically the first line of defense. They utilize surface chemistry to bind to polar impurities, helping to fractionate the extract before it hits the secondary "polishing" layers.

Silica Gel (Silicon Dioxide)

Silica is the backbone of most CRC stacks. While it exists in many forms, Silica 60Å is the industry standard for cannabis.

• pH Profile: Neutral (~7.2), making it safe for acid-sensitive terpenes.

• Function: It acts as a stationary phase that slows down the movement of polar pigments.

• Technical Spec: With a particle size of 30–200 microns, it offers a balance between effective surface area and manageable flow resistance.

Activated Alumina

Alumina is a highly porous form of aluminum oxide.

• pH Profile: Basic (9.0–10.0).

• The "Dryer": It has a much higher affinity for water than silica. It is often used when the source material has higher moisture content or when a lighter touch of color remediation is desired.

• Particle Size: 28–48 microns, providing a tight, effective filter bed.

Magnesium Silicate (Mag-Sil)

Often referred to by the brand name Mag-Sil PR, this media is specifically engineered for the removal of complex polar compounds. Particle size ranges from 150 - 250 microns.

• Pesticide Remediation: Its most vital role is its ability to bind to certain pesticide compounds that other media will miss.

• Critical Note: Never substitute Mag-Sil with food-grade Magnesol. While chemically similar, Magnesol is designed for frying oil and lacks the purity and particle consistency required for solvent-based extraction.

Diatomaceous Earth (DE)

DE is not a remediation media in the chemical sense, but a mechanical filter aid.

• Prevention of "Plugging": Because other media (like clays) are very fine, they can easily clog filters. DE creates a "scaffold" that keeps the media bed porous.

• Grades: It ranges from 1.85 to 200 microns. Choosing the right grade is essential to preventing DE particles from passing into the final oil.

2. Non-Polar Filtration Media: The Polishing Layers

Non-polar media are generally placed further down the stack to capture the impurities that have been "pushed" through the polar layers.

Bentonite Clay (T-5, Lustermax, Montmorillonite)

Bentonite is a volcanic ash-derived clay used for its incredible bleaching (decoloring) power. Particle size averages 60 microns.

• Flow Dynamics: It has a dense structure, leading to a slower flow rate. This increases "residence time," allowing the clay more time to pull pigments out of the solvent.

• pH: Generally basic (~9.0), which helps in stabilizing certain oil fractions.

Attapulgite Clay (B80, B81, Fuller’s Earth)

Attapulgite is the "high-speed" alternative to Bentonite. Particle size ranges from 44 - 74 microns.

• High Flow & Bleaching: It is preferred for larger-scale operations where speed is a priority. It is exceptionally good at removing chlorophyll (greens) and pheophytins (browns).

• Variability: Unlike Bentonite, Attapulgite is often sold in various pH-treated versions. Always check the COA (Certificate of Analysis) to ensure the pH aligns with your specific extraction parameters.

Activated Carbon (Activated Charcoal)

Carbon is the "nuclear option" of filtration. It has the largest internal surface area of any media listed.

• The Trade-off: While it is unparalleled at removing heavy pigments and foul odors, it can also strip away desirable flavors (terpenes) if overused.

• Filtration Hazard: Carbon particles can break down to 0.5 microns. You must use a specialized "hard" filter or a sub-micron secondary filter to ensure no carbon dust enters the final product, as it can cause "peppering" in the extract.

3. Granular & Zeolite Media: The High-Volume Solution

Zeolites are naturally occurring or synthetic aluminosilicates that act as molecular sieves. In CRC, they are often used as a pre-mixed, granular composition.

• Maximum Efficiency: Because they are granular (larger beads) rather than fine powders, they allow for exceptionally high flow rates.

• Contact Time: The trade-off for speed is a lower surface area-to-volume ratio. To use Zeolites effectively, you must have precise control over your flow rate to ensure the solvent doesn't "channel" through the media too quickly.

• Economics: Zeolites are typically less refined than specialty clays or silicas, making them the most cost-effective choice for basic extractions.