Carbon can hold 150% of its weight in contaminants because it has a large surface area to adsorb particles. Every gram of carbon has 1,100 square meters of adsorption area specialized in capturing pigments like chlorophyll and carotenoids, heavy metals like Fe, Cu, Zn, Hg, Mg, etc..., polyaromatic hydrocarbons (PAHs) as well as fats and waxes.
That being said, carbon must be used sparingly to avoid unnecessary losses. Lab tests are essential to determine the right amount to use. In general, carbon works best for green colored ethanol crude to remove color and contaminants, and in lesser dosages to remove taste and smell from BHO or CO2 crude. In all cases, it removes heavy metals and contaminants that promote oxidation that browns distillate.
We recommend a finely powdered carbon for fast adsorption, one which is food grade and complies with HACCP guidelines. We recommend Carbon in Leach adsorption where carbon is added to your tincture after extraction and agitated. Other methods like lenticular or carbon-infused depth filter sheets and carbon columns do work but there are tradeoffs. The main disadvantage of CIL is the inconvenience and labor costs.
For CIL, carbon must be added to crude/solvent tincture and agitated for 20-30 minutes. Carbon is added to the tincture in 3-4 portions to promote better adsorption. This is because carbon's affinity to certain particles changes as the carbon pores are used up. Adding fresh carbon in stages reduces the overall dosage necessary and ultimately removes mo color and heavy metals.
Carbon performs better in cool solutions than in hot solutions. This is due to the need for intimate contact with a particle for carbon to adsorb these contaminants. Since colder solutions are more viscous, this process is greatly reduced so agitation must be prolonged.
Carbon strips what it has adsorbed when in very hot solutions. This desorption (stripping) increases exponentially in the presence of ethanol or other solvents. Though you may not notice a visual difference between cool and hot adsorption, contaminants remain captured on cool solutions better than hot. Cold adsorption is not recommended as it tends to capture cannabinoids. Room temperature is a good rule of thumb.
Also, it is recommended to use carbon on degummed and dewaxed solutions, as these gums and waxes tend to clog the carbon pores. Dosage of carbon depends on the level of contaminants but can be as little as 0.5 grams of carbon per liter or kilogram of crude, or as high as 50 grams per liter.
Lab-scale testing is critical for this process and can greatly help you reduce costs and increase potency.
By following all these recommendations you will use very little carbon with amazing results, all while keeping losses low.