Mesh size
Mesh describes particle-size distribution. Finer grades can behave differently during dispersion and processing, so the requested mesh should be stated explicitly rather than inferred from a product name.
Viscosity
Viscosity is one of the most commercially important parameters for many guar gum grades. A buyer should specify the concentration, temperature, hydration time and test method used for the viscosity measurement, because changing the method can change the reported number.
Moisture, ash and insoluble residue
These parameters help describe the condition and purity of the powder. Acceptance limits should be linked to the final application, storage conditions and applicable standard rather than using a one-size-fits-all number.
Microbiology and food/pharma controls
For sensitive applications, buyers may specify total plate count, yeast and mould, pathogens and other controls. Pharmaceutical and nutraceutical programs may also require additional documentation or supplier qualification.
How to compare two COAs
Compare the same test methods and units first. Then confirm that both samples are the same grade and processing route. A lower price is not directly comparable if the viscosity, particle size or microbiological specification is different.
COA checklist
Before approving a lot, verify product name and grade, lot number, manufacturing or packing date where applicable, test methods, specification limits, actual results, laboratory responsibility and the link between the COA and the shipment lot.