Yellow Powder at Destination: The Plant Checks the COA First

September 29, 2026 · Technical Article

A photo of yellow powder at a destination warehouse is a complaint. It is not yet a cause. Zhongzhi Chemical treats claim prevention as a file order: the batch COA against the contract first, the process record second. Sodium metasilicate powder is one product line at the Changyi plant. The same order of checks applies when appearance matters on that line — detergent builders and industrial cleaning powders especially.

Yellow powder on arrival — what should you check first?

Check the batch COA against the contract. Read iron, and whiteness if the purchase order names it, before anyone opens a mill or argues from the photo. If iron is over the contracted ceiling, the lot failed on paper and the process review explains why. If the COA is inside the contract and the color still looks wrong, then the process file and the retention sample are the next step.

Illustrative industrial scenario (composite): Rewritten from factory training. An industrial cleaning buyer reported powder that looked yellow on arrival. The lot COA showed iron slightly above the ceiling written on that contract. The plant replaced that lot and traced iron fines to wear on milling equipment. No customer is named. No price, credit, or new iron percentage is stated.

The file order

Step What the plant opens
1 Lot marks on the bags versus the COA lot number
2 Iron result versus the Fe ceiling on the contract
3 Whiteness, only when the PO names a method and a floor
4 Process record — milling and screening wear — after the COA is read
5 Written decision: replace the failed lot, or accept it against a revised window

Iron bands you can write into a PO

Use grade language already published on this site for anhydrous framing: Superior Fe ≤0.010%, First Fe ≤0.02%. Confirm the result on the batch COA, not from a catalog sentence. This page does not publish a new iron result and does not publish a whiteness percentage. If your contract needs whiteness, send the method and the floor you already use; plant QA will put that row on the release COA.

In the composite, step 2 was enough to see the miss: iron sat above the contracted ceiling. Color was the symptom. The COA was the evidence. Only then did the plant open the process file. Worn milling surfaces were shedding iron fines into the powder. That is a maintenance cause, found after the certificate, not instead of it.

How to read each COA line, including Fe and whiteness when they are reported, is on how to read a batch COA. Modulus is a separate stop: spec sheet versus batch COA. Application context for detergent and cleaning formulas is on the detergent application guide.

What prevention looks like before stuffing

  • Fe ceiling (and whiteness, if you require it) written on the PO before production.
  • Release COA signed against that PO before the container is stuffed. Export loading for this plant is at Qingdao.
  • Milling and screening condition on the checklist, because wear metal is a known path for iron fines.
  • Retention sample kept against the lot number on the COA.
  • Sample COA files on Downloads show format. The shipment COA is the lot you bought.

A phone photo can start the conversation. It cannot close it. Ask for the lot COA, compare Fe to the contract, and then ask what the plant found on the mill. Volume for a replacement or a new order is the current supply plan, confirmed when you write.

Primary CTA (this site only): /contact

Contact Zhongzhi Chemical

For an industrial cleaning powder, send the Fe ceiling, any whiteness floor you already use, form, packing, and destination. Inquiry stays on this site.

Contact Zhongzhi

Zhongzhi Chemical · Changyi · claim prevention · /contact

Related Articles