The short answer
A COA (certificate of analysis) reports measured test results for one specific lot of resin, with the lot number and the producer's specification limits. It shows what you actually received, while the data sheet shows what the grade is designed to be.
COAs are the paper trail of resin buying. They let a molder confirm the incoming lot matches the specification, trace a problem back to a lot, and show customers that material is controlled.
What a COA usually shows
| Item | Why it matters |
|---|---|
| Lot or batch number | Ties the results to the exact material you received |
| Grade name and producer | Confirms you got the grade you ordered |
| Test results | Measured values for that lot, such as melt flow, density, moisture or ash |
| Specification limits | The producer's acceptable range for each reported property |
| Test methods | The ASTM or ISO method used, so results can be compared |
| Date and sign-off | When it was tested and who released it |
COA vs. technical data sheet
The data sheet lists typical values measured on standard test bars; it is the same for every lot. The COA lists the values measured on your lot, usually for a smaller set of properties chosen by the producer. If a property is critical to your part and it is not on the COA, ask for it before ordering, or test it on receipt. See how to read a resin data sheet.
How to check a COA when material arrives
- Match the lot number on the COA to the gaylord or bag label.
- Confirm the grade and color are what you ordered.
- Compare each result to the specification limits and to your own spec.
- Watch melt flow and moisture, the values most likely to change how a lot runs.
- File it with the lot so you can trace any later problem.
What a COA is not
A COA is not a certification or an approval. UL listings, automotive approvals and food-contact compliance letters are separate documents tied to a specific grade. Ask for those separately when your part needs them. See FDA and food-contact resin and UL 94 flame ratings.
How we handle it
Every lot we supply ships with a COA, tested to ASTM or ISO methods. Tell us which properties matter for your part and a polymer chemist will confirm what is reported before you order. We aim to send your quote within one to three business days.
Common questions
What does COA stand for in plastics?
Certificate of analysis. It reports measured test results for a specific production lot of resin, along with the lot number and the producer's specification limits.
Is a COA the same as a data sheet?
No. A data sheet lists typical properties for a grade. A COA lists measured results for one lot. The data sheet describes the grade; the COA documents what shipped.
What properties are usually on a resin COA?
It varies by producer and grade. Common items are melt flow, density, moisture, ash or filler content, color values and sometimes tensile or impact. Ask before you buy if you need a specific property reported.
Should every lot of resin come with a COA?
For most molders and extruders, yes. It ties the material to a lot number, gives you something to check against your specification, and is often required by customers and quality systems.
Does a COA mean the resin is certified?
No. A COA reports test results for a lot. Certifications and approvals, such as UL listings or food-contact compliance, are separate documents tied to a specific grade.
Tell us the grade you need
A polymer chemist reviews every request, then matches your grade or finds a qualified equivalent and prices it.
What to send for an accurate quote
- The grade name, from any supplier, or a data sheet
- Color (natural, black or a custom match)
- Fill type and percentage, if any
- Melt flow, if you know it
- Quantity for this order and what you use in a year
- Ship-to city and state or province