VOC regulations and low-VOC finishes

Overview

VOCs are the solvents that leave a finish as it dries. They contribute to ground-level ozone, which is why air-quality rules cap them, and many are also flammable or harmful to breathe. The rules are about the product as sold, in grams of VOC per litre of coating (g/L), not about your exposure while you work. This entry is a US-only summary; European and other countries' rules differ and are not covered. It is a guide to reading the numbers, not legal advice.

When to use

Read this before buying a finish if you are choosing between solvent-borne and waterborne products, if you live in California or another state with its own rules, or if you sell finished work and must know which products you may use.

Materials and tools

• The technical data sheet (TDS) and safety data sheet (SDS) for the product. VOC content is stated in g/L, often "as supplied" and sometimes "less exempt compounds".
• The can label, which in regulated areas carries the VOC content.

Steps

1. Know what the federal rule covers. The US EPA's national architectural coatings rule (40 CFR part 59, subpart D) applies to coatings "recommended for field application to stationary structures" and excludes, for example, shop-applied industrial finishing and coatings for boats. Whether a woodworking finish in a hardware store can falls under it depends on how the maker recommends it.
2. Find the category. The federal table sets limits by category, in g/L. The ones that matter to woodworkers include: varnishes 450; lacquers (including lacquer sanding sealers) 680; sanding sealers other than lacquer 550; sealers (including interior clear wood sealers) 400; clear shellacs 730 and opaque shellacs 550; conversion varnish 725; clear and semitransparent stains 550, opaque stains 350; wood preservatives 550 (opaque 350); stain controllers 720. Floor coatings and some other categories have separate limits. I read the current eCFR text; check it for the date of your purchase, because limits change.
3. Remember the most-restrictive rule. If a label claims more than one category, the most restrictive limit applies.
4. Check state and regional rules. California's South Coast Air Quality Management District (Rule 1113, Architectural Coatings) limits VOC content in its own area, and the Ozone Transport Commission, a multi-state body in the Northeast and Mid-Atlantic, develops model rules that member states may adopt. I did not read the California Air Resources Board, SCAQMD or OTC limit tables, so this guide gives no numbers for them. Local rules can be stricter than the federal ones, which is one reason a maker may sell a different formula in different places.
5. Compare actual numbers. Waterborne finishes (Water-based polyurethane, Waterborne acrylic and urethane-acrylic topcoats, Water-based lacquer) usually carry lower VOC figures than solvent-borne lacquers and varnishes, but read the sheet rather than the claim.

Common problems

• "Low-VOC" on a label. The sources I opened do not give a single national definition for the phrase. Treat it as a marketing term and look up the g/L number.
• "Zero VOC" or "VOC-free". Check the data sheet; a product can meet a category limit without being near zero.
• Water-based does not mean harmless. Waterborne finishes may still contain coalescing solvents, and some contain sensitising chemicals; read the SDS. Low-VOC does not mean no respirator for spraying.
• Epoxy. West System says its epoxies have low VOC, but vapours can build up in unvented spaces.
• Product no longer sold in your state. Not a quality change; a regulatory one.

Safety and environment

VOC limit and safety are separate questions: a low-VOC product can still be an irritant or sensitiser, so read the SDS. For the occupational side, see Finishing shop ventilation and PPE. For the flammability of rags and waste, see Oily rag safety and Finishing safety and disposal.

Related

• Water-based polyurethane, Waterborne acrylic and urethane-acrylic topcoats, Water-based lacquer, Water-based pigment stain: lower-VOC routes
• Nitrocellulose lacquer, Conversion varnish, Shellac: categories with their own federal limits
• Finishing shop ventilation and PPE, Finishing safety and disposal
• Kids' furniture and high-wear finishes