RWA purity drives should use the same strip panel every quarter so vendors are compared on one protocol. Colour charts differ by brand — photograph the pack insert next to the strip.
Starch
Starch is added to restore body after watering. Iodine-based strips or a drop of tincture of iodine in a spoon of milk: blue-black is a fail.
False calm: freshly boiled milk can brown slightly. Read within the kit’s window (usually 30–60 seconds).
Urea
Urea raises lactometer readings and solids-not-fat on paper. DMAB or branded urea strips turn a distinct yellow-to-brown versus the control pad.
A positive urea strip plus a “healthy” CLR is the classic sophistication pattern. Log both on the vendor card.
Neutralizers
Sodium carbonate / bicarbonate masks acidity from spoilage. Neutralizer pads shift toward green or blue. Sour smell with a “pass” acidity story is a reason to re-test, not to ignore the strip.
Synthetic detergent
Detergent increases froth and can fake richness. Methylene-blue or detergent-specific pads show a strong colour versus a pale control. Shake a sealed vial: persistent soapy foam is a kitchen corroboration, not a lab result.
RWA batch protocol
Collect anonymised 50 ml from three households on the same route, same morning. Test within two hours, chilled. Publish pass/fail counts, not vendor gossip. That 30% PTS checkpoint is “standard verification,” not a viral screenshot.