Determination of Non-Volatile Matter in a Volatile Solvent: Essential Quality Control for Coatings and Adhesives
In the coatings, adhesives, inks, and specialty chemical industries, product quality often hinges on precisely controlling the amount of solid material remaining after the carrier solvent evaporates. Non-volatile matter (NVM) — the solids content remaining after evaporation of volatile components — is a critical quality parameter that governs film build, viscosity, application properties, coating weight, and product performance. In the chemical & coatings industry, accurate NVM determination is both a production quality control checkpoint and a regulatory compliance parameter for VOC (volatile organic compound) reporting.
What Is Non-Volatile Matter?
Non-volatile matter represents all components of a liquid product that do not evaporate under defined test conditions — temperatures, duration, and test environment that are specified to distinguish volatile from non-volatile components for the specific product class.
For coatings, NVM is synonymous with “solids content” — the actual film-forming material (resins, pigments, fillers, curing agents) that remains on the substrate after application and drying. For adhesives, NVM is the active bonding material that provides cohesive strength. For inks, NVM is the colorant and binder that produces the printed image.
NVM directly determines:
- Film build — the thickness of coating applied per coat is proportional to NVM
- Coverage rate — the area covered per liter of coating scales with NVM (higher solids → more area)
- VOC content — regulatory reporting of VOC content often derives from volatile matter (1 − NVM)
- Mix ratios — for two-component systems, NVM guides component proportioning
Standard Test Methods for Non-Volatile Matter
ASTM D2369 — Water Content of Volatile Solvents and Chemical Specialties
While primarily a water-content method, D2369 establishes the framework for volatile-content determination that underlies NVM testing.
ASTM D1193 / ISO 3251 — Non-Volatile Content of Paints, Varnishes, and Binders
ISO 3251 — Paints, varnishes, and plastics — Determination of non-volatile matter content — is the most internationally harmonized method for coating NVM determination:
Procedure:
- A flat aluminum dish (Petri dish) is tared (weighed empty)
- A precisely weighed specimen (1.0 ± 0.1g for most solvent-borne coatings) is spread uniformly on the dish using a glass rod
- The dish is placed in a forced-circulation oven at a specified temperature (typically 105°C ± 2°C for general purpose, or higher/lower for specific products) for a specified duration (typically 60 minutes)
- The dish is cooled in a desiccator and reweighed
- NVM (%) = (mass after evaporation / original specimen mass) × 100
Critical parameters:
- Temperature — higher temperatures increase evaporation efficiency but may thermally degrade or cross-link some resins, giving artificially high NVM. Standard temperatures range from 50°C (low-boiling solvents) to 200°C (high-boiling vehicle components).
- Duration — longer drying times improve the completeness of solvent removal. The specified time must ensure complete evaporation of all volatile components.
- Specimen spreading — thin, uniform spreading (typically 0.3–0.5mm wet film) is essential to ensure complete solvent evaporation without surface crust formation that traps volatile components.
ASTM D5095 — Non-Volatile Content of Silanes, Siloxanes, and Silane-Siloxane Blends
For silicon-based products, standard oven evaporation methods may be inappropriate due to silane hydrolysis during testing. ASTM D5095 specifies modified conditions applicable to the specific chemistry of silicon-based surface treatments and waterproofing agents.
ASTM D2369 — Volatile Content of Coatings
ASTM D2369 is specifically designed for coatings in which VOC regulatory compliance requires accurate measurement of volatile content. Unlike ISO 3251, which measures mass remaining, D2369 quantifies the volatile fraction directly — enabling calculation of VOC content when combined with water content and exempt solvent determinations per EPA Method 24.
Non-Volatile Matter in Specific Product Categories
Solvent-Borne Coatings
For traditional solvent-borne architectural and industrial coatings, NVM typically ranges from 30% to 60% by weight. High-solids coatings (≥60% NVM) have been developed primarily to reduce VOC emissions — delivering more coating per liter of product applied while meeting increasingly stringent air quality regulations. Accurate NVM measurement is essential for verifying that high-solids formulations meet both performance and regulatory specifications.
Waterborne Coatings
Waterborne coatings use water as the primary carrier — NVM measurement requires careful temperature selection to evaporate water (100°C) without thermally degrading the polymer binder. The presence of coalescing solvents (glycol ethers) that evaporate more slowly than water can complicate NVM measurements—requiring extended drying times or elevated temperatures to ensure complete removal.
Adhesives and Sealants
Contact cements, pressure-sensitive adhesives, and construction sealants use NVM as a quality-control parameter that directly governs adhesive-layer thickness, tack, and bond strength after drying. ASTM D2834 specifies NVM testing for rubber-based adhesives; ISO 3251 applies to most other adhesive types.
Industrial Ink and Printing
Printing inks — flexographic, gravure, and screen printing — are characterized by NVM to control ink density, print thickness, and color strength. Overprinted gloss varnishes are formulated to target NVM values that achieve specified gloss levels and drying characteristics.
Regulatory Significance: NVM and VOC Reporting
Environmental regulations in the US (EPA Rule 40 CFR Part 60 Appendix A-7, EPA Method 24), EU (Directive 2004/42/CE), and many national regulations govern VOC emissions from coatings. These regulations typically express VOC limits and product compliance in terms of grams of VOC per liter of coating — calculated from the volatile content (1 − NVM), water content, and exempt solvent content measured by standardized methods.
Accurate NVM determination is therefore not just a product quality parameter but a legal compliance requirement for coating manufacturers selling into regulated markets.
Conclusion
Determining non-volatile matter per ISO 3251 and ASTM D2369 is both a product quality checkpoint and a regulatory compliance requirement for coating manufacturers. Accurate NVM measurement directly governs film build, coverage rate, and VOC reporting — making precise temperature control, specimen spreading, and drying duration critical to generating defensible results. For high-solids and waterborne formulations operating under increasingly stringent VOC regulations, NVM testing is the analytical foundation that connects formulation chemistry to real-world performance and legal compliance.
Why Choose Infinita Lab for Non-Volatile Matter Determination Testing?
Infinita Lab provides non-volatile matter (NVM) determination per ISO 3251, ASTM D2369, and ASTM D2834 — combined with VOC content determination per EPA Method 24 and ISO 11890, water content by Karl Fischer titration, and near-infrared NVM screening — supporting coatings, adhesives, ink, and specialty chemical manufacturers across the chemical & coatings industry with rapid, accurate solids content data for quality control, product development, and regulatory compliance. Contact Infinita Lab at infinitalab.com to discuss NVM testing and VOC compliance services for your products.
Frequently Asked Questions
Why does specimen spreading affect NVM measurement results? Thick specimen layers trap solvent beneath surface skin formed during outer layer drying, preventing complete evaporation within test duration. ISO 3251 specifies maximum specimen mass relative to dish area to control effective film thickness and ensure complete solvent evaporation.
How does oven temperature selection affect NVM accuracy? Temperature must ensure complete solvent evaporation without thermally decomposing non-volatile components. Most solvent-borne coatings use 105°C for 60 minutes. High-boiling solvents require 125°C. Temperature-sensitive epoxies and moisture-cure polyurethanes require lower temperatures of 50–80°C or vacuum drying to prevent thermal decomposition.
Can NVM be measured by methods other than gravimetric evaporation? Yes. NIR spectroscopy provides rapid non-destructive NVM determination by measuring solvent absorption bands, widely used for production line monitoring where gravimetric methods are too slow. Karl Fischer titration specifically measures water content in waterborne coatings where distinguishing water from non-aqueous volatiles is needed for VOC calculation.
What is the difference between NVM by weight and NVM by volume? Weight-based NVM expresses residue mass relative to original specimen mass. Volume-based NVM expresses dry film volume relative to wet coating volume, used for coverage rate calculations and film build prediction. Volume NVM requires both dry film density and wet coating density for accurate calculation.
How is NVM used to calculate coating coverage rate? Theoretical spreading rate (m²/L) = (NVM_volume × 10) / dry film thickness in µm. A coating with 40% volume NVM at 75 µm dry film thickness achieves 53 m²/L theoretically. Practical coverage rates are lower due to overspray and equipment retention losses during application.
