Herb Cleaning, Grading and Grinding Explained

Raw botanicals often go through several processing steps before they are ready for a manufacturer. Understanding these steps helps buyers ask the right questions and specify what they need.

Cleaning and sorting

Cleaning removes dust, soil, stones and other foreign matter. Sorting separates the required plant part from other parts and removes off-grade material. The level of cleaning required depends on your end use.

Grading

Grading groups material by agreed characteristics, such as size, appearance or other parameters set by the buyer. Clear grading criteria make it easier to receive consistent lots.

Grinding and sieving

Grinding turns whole or cut material into powder, and sieving controls the particle size to the requested mesh. Different materials grind differently, so the achievable mesh range should be confirmed per product.

Blending and repacking

Blending combines materials to a buyer's formula. Repacking puts material into the pack type and size the buyer needs.

What to discuss with your supplier

• Which steps are done in-house and which through partners.
• The cleaning or grading standard you expect.
• The mesh size and any sieve test method.
• Packaging and labelling for the processed material.