Introduction: The same coating—VOC values measured under different standards may differ by 50–100 g/L
VOC (Volatile Organic Compounds) is the most critical environmental indicator in the coatings industry—directly determining whether a product can be legally marketed. Yet for the same coating, VOC values measured under the three standards GB 30981-2020 (China), ISO 11890 (EU), and ASTM D2369 (US) may differ by 50–100 g/L—”the gap comes from three variables”: baking temperature (105°C vs 110°C), moisture deduction method, and exempt solvent determination. “Inaccurate measurement = the difference between heaven and earth in terms of compliance or non-compliance.”
The three major international standard systems for coating VOC testing — GB/T 23985 (China / equivalent to ISO 11890) / ISO 11890 (EU / 105-110°C baking / moisture deduction — Karl Fischer or gas chromatography) / ASTM D2369 (US / 110°C / exempt solvents — acetone / PCBTF / TBAc not counted) — differ mainly in baking conditions, moisture correction methods, and exempt solvent lists. “Formulator — must — clearly — know — the — VOC — standard — of — the — target — market — and — choose — the — correct — testing — method.”
FAQ
Q1: Why does a 5°C difference in baking temperature—VOC results differ by >50g/L?105°C——(GB)——vs——110°——C——(ISO——/——ASTM)——This——5°C——makes——little——difference——for——low-boiling——solvents——(acetone/toluene——boiling——point————5——0——g——/——L””This——may——lead——to——”non-compliant”——products——being——misjudged——as——”compliant””””。
Q2: Exempt solvents—acetone “not counted as VOC” but how is it handled in testing?Exempt solvents (acetone/PCBTF/TBAc—EPA/GB exempt)—in VOC calculation “deducted” but in testing “they—still—volatilize” “testing—requires” separation—quantification (gas chromatography—GC)—identify—each—volatile—substance “those—belonging—to—exempt—solvents—subtracted—from—total—VOC” “those—not—exempt—=—counted—as—VOC” “this” identification—deduction—operation—accuracy—directly—determines “final—VOC—value” “GC—instrument—precision—chromatography—column—selection” calibration—standard “are—all—error—sources”.
Summary
VOC testing — GB/ISO/ASTM three major systems — baking temperature / moisture deduction / exempt solvents as three variables. “Different standards — different results — different compliance judgments.” Formulators must be clear about the testing standards of the target market. Kexin New Materials provides VOC testing consultation and compliant formulation design. “L-e-t-y-o-u-r-V-O-C-n-u-m-b-e-r-s-w-i-t-h-s-t-a-n-d-t-h-e-t-e-s-t-o-f-a-n-y-s-t-a-n-d-a-r-d.”