Primer and topcoat do different jobs
The Forest Products Laboratory describes a primer as designed to be sticky and flexible, gripping the wood and moving with it; a topcoat is made hard, cleanable and scratch-resistant — properties that would make a poor primer. A product sold as paint and primer in one, it says, is not optimal at either job. Primers also even out colour and block what migrates out of the wood.
Knots and bleed
Knots and highly coloured woods contain extractives that can bleed through paint as stains. The Laboratory's advice is plain: another coat of the same paint will not stop it; a stain-blocking primer will. Zinsser says its B-I-N Advanced, a synthetic-shellac primer, seals tannin, knots and sap streaks, and asks for 2 hours' drying over knots and stains — longer than its 45-minute recoat elsewhere.
| Product | Type | Touch | Recoat | Use or cure |
|---|---|---|---|---|
| Zinsser B-I-N Advanced | Synthetic shellac primer | 25 min | 45 min; 2 h over knots | Fully cured in 7 days |
| Benjamin Moore ADVANCE | Waterborne alkyd paint | 4–6 h | 16 h | Tabletops back in use after 5–7 days; up to 30 days to full hardness |
| General Finishes Milk Paint | Water-based acrylic paint | 30 min | 2 h | Cure 21 days |
Zinsser and General Finishes times at 70°F and 50% RH; Benjamin Moore's at 77°F and 50% RH. Each maker's figures are for its own product only.
Furniture paints
- Hard enough to use is not cured. Benjamin Moore says not to put shelves or tabletops painted with ADVANCE back into service for at least 5 to 7 days, and that optimum hardness can take up to 30 days. General Finishes gives its Milk Paint 21 days to cure.
- Names can mislead. General Finishes' Milk Paint is, by its data sheet, a water-based acrylic paint.
- Primer or not. General Finishes says its Milk Paint can be used without a primer, but recommends its stain blocker under white and light colours; Benjamin Moore specifies a primer under ADVANCE on new wood and sanding cabinetry with 220 grit or coarser before priming.
- Wear. General Finishes suggests up to three coats of a clear topcoat over Milk Paint on high-use surfaces; Benjamin Moore notes ADVANCE may yellow slightly, more in dark or poorly ventilated places.
- Gloss shows everything. The Forest Products Laboratory notes that high-gloss enamels accentuate planer marks, raised grain and joints, so preparation matters more under a glossy paint.
- Do not thin modern waterborne paints, the Laboratory advises, unless the label allows it.
Choosing among them by what is underneath and by how the piece will be used is covered in how to choose paint for wood.
Lead, old paint and children's furniture
Safety— Old paint may contain lead
EPA lists refinishing old furniture as a job that can expose you to lead. Before sanding or stripping an old painted piece, read refinishing furniture and stripping.
For new work, CPSC limits lead in paint and similar surface coatings on children's products and certain furniture to 0.009 percent (90 parts per million). The rule covers movable furniture such as beds, chairs, tables and dressers, CPSC says, but not built-in cabinets or doors. It is a limit on products sold; anyone making children's furniture for sale should read the regulation and its testing requirements directly.
Painting wood
- Old paint checked for lead before sanding
- Sanded and cleaned as the paint maker specifies
- Knots and resinous areas spot-primed with a stain-blocking primer
- A full primer coat where the paint maker calls for one
- Recoat times kept, and use delayed to the maker's figure
- Ventilation while the paint dries
Sources
Times and VOC figures are each maker's for its own product, at the conditions given. A paint's VOC content describes its solvent, not its safety or durability. CPSC's lead limit is a legal limit on products sold, stated as CPSC states it; makers of children's furniture for sale should read the regulation itself.
- 1.
Christopher G. Hunt. Wood Handbook: Wood as an Engineering Material (FPL-GTR-282), Chapter 16: Finishing Wood. USDA Forest Service, Forest Products Laboratory, 2021.
Used for: Primers as sticky and flexible, topcoats as hard and cleanable, and 'paint and primer in one' optimal for neither; stain-blocking primers against extractive bleed from knots and coloured woods, which another topcoat will not stop; gloss enamels accentuating surface flaws; modern waterborne paints not to be thinned.
- 2.
Technical Data BIN-01, B-I-N Advanced Synthetic Shellac Primer. Rust-Oleum (Zinsser).
Used for: B-I-N Advanced as a synthetic shellac primer that seals tannin, knots and sap streaks and goes under or over latex or oil-based paint: touch in 25 minutes, recoat in 45, 2 hours for knots and stain blocking, fully cured in 7 days, at 70°F and 50% RH.
- 3.
Technical Data Sheet, ADVANCE Waterborne Interior Alkyd Satin 792. Benjamin Moore.
Used for: ADVANCE as a waterborne alkyd: touch in 4–6 h and recoat in 16 h at 77°F and 50% RH; no heavy abrasion and no shelves or tabletops back in service for at least 5–7 days; up to 30 days for optimum hardness; cabinetry sanded with 220 grit or coarser before priming; a slight yellowing possible; 48.5 g/L VOC.
- 4.
Technical Data Sheet, Milk Paint. General Finishes, 2020.
Used for: Milk Paint as a water-based acrylic paint despite its name: touch in 30 minutes, recoat in 2 hours, cure in 21 days at 70°F and 50% humidity; raw wood sanded up to 220; usable without a primer, with a stain blocker recommended under white and light colours; up to three topcoats on high-use surfaces.
- 5.
Reduce the Risk of Lead Exposure at Home. U.S. Environmental Protection Agency, 2026.
Used for: Refinishing old furniture as a source of lead exposure; pre-1978 homes and lead-based paint.
- 6.
Lead in Paint (business guidance; 16 CFR part 1303). U.S. Consumer Product Safety Commission.
Used for: The 0.009% (90 ppm) limit on lead in paint and similar surface coatings on children's products and certain furniture articles, covering movable furniture such as beds, chairs, tables and dressers but not built-in cabinets or doors.
- 7.
Volatile Organic Compounds' Impact on Indoor Air Quality. U.S. Environmental Protection Agency.
Used for: VOCs from paints, and health effects that vary greatly by compound.
About this guide
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