Astm D61821 Pdf ((free)) < 2026 Edition >

Based on the numbering sequence and common ASTM standards, it is highly likely you are looking for (Standard Test Method for Nonvolatile Matter of Unsaturated Polyester Resins) or possibly ASTM D618 (Standard Test Methods for Water Absorption).

The primary goal of ASTM D618-21 is to establish reproducible results by bringing plastic specimens into a consistent state before and during testing. Conditioning is typically performed to: astm d61821 pdf