Paint Types + Chemistry Reference

Overview

Paint chemistry determines which paint to use where. Match wrong + the paint fails. This reference covers the categories, what they're best for, + how they're made.

Paint anatomy

All paint has 4 components:

1. Binder / resin - the film-forming polymer (what holds it together)
2. Pigment - the color + opacity
3. Solvent - the carrier (water or oil)
4. Additives - drying agents, mildewcides, surfactants

The binder determines paint type + properties.

Categories by binder

Latex / acrylic (water-based)

• Binder: acrylic polymer (premium) or vinyl-acrylic (mid-grade)
• Solvent: water
• Dry time: touch dry 30 min - 2 hrs; recoat 2-4 hrs
• Cure time: 30 days to full hardness
• Cleanup: soap + water
• Smell: low
• VOC: low (most < 50 g/L; "zero-VOC" available)
• Flexibility: excellent (breathes, won't crack with substrate movement)
• UV resistance: excellent for exterior
• Best for: most interior + exterior residential, ceilings, walls, trim
• Not best for: high-wear surfaces with very specific cleaning requirements

100% Acrylic vs Vinyl-Acrylic:

• 100% Acrylic = premium, lasts 15-25 years exterior
• Vinyl-acrylic = mid-grade, lasts 7-12 years exterior

Use 100% acrylic for exterior + high-quality interior. Worth the premium.

Oil-based / Alkyd

• Binder: alkyd resin (synthetic oil-based polymer)
• Solvent: mineral spirits
• Dry time: touch dry 6-8 hr; recoat 16-24 hrs
• Cure time: 30-60 days
• Cleanup: mineral spirits (more difficult)
• Smell: strong VOC odor
• VOC: high (300-450 g/L typically; regulated in many states)
• Flexibility: rigid (cracks with substrate movement over time)
• UV resistance: poor for exterior, but not because of the yellowing. Alkyd yellowing is oxidation of the oil and it is WORST where there is no light: closets, behind doors, inside cabinets. Daylight partly bleaches it back out. What rules oil out on an exterior is chalking and embrittlement under UV.
• Best for: trim that needs hardness, doors, cabinets, metal
• Not best for: most modern residential (acrylic now matches performance)

Why oil is being phased out:

• Regulations: California, NY, others have banned/restricted high-VOC paints
• Modern acrylics match oil for hardness
• Oil yellows over time (especially whites)
• Disposal regulations

When oil is still right:

• Heavy-duty trim/doors (some refinishers prefer)
• Metal (with rust-inhibiting properties)
• Touch-up to existing oil finish (matching)

Latex-modified acrylic (waterborne alkyd)

• Binder: alkyd in water emulsion
• Cleanup: water
• Hardness: oil-like
• Smell: lower than oil
• VOC: medium
• Best for: trim, doors, cabinets - "hardness of oil, cleanup of latex"

Newer category bridging oil + latex performance.

Shellac

• Binder: lac resin (natural)
• Solvent: denatured alcohol
• Dry time: 30 minutes
• Best for: stain-blocking primer (water, smoke, tannins)
• Reference product: Zinsser B-I-N (B-I-N is Zinsser's shellac primer, not a separate brand)
• Not for: outdoor exposure, hot surfaces

Use as primer ONLY; rarely as topcoat.

Specialty paints

Epoxy:

• 2-part chemistry mixed before use
• Extreme hardness + chemical resistance
• For: garage floors, basement floors, industrial
• Difficult to apply

Elastomeric:

• Flexible polymer paint
• Bridges hairline cracks (1/16")
• For: exterior stucco, masonry
• Premium pricing

Mineral / lime paint:

• Inorganic binder
• Breathable, durable, expensive
• Historic preservation, plaster

Sheens (within each chemistry)

Within latex or oil, sheens determine reflectivity:

Sheen rule: higher sheen = more washable + more durable + shows more surface imperfections.

Pigment quality

Premium paints have:

• More pigment (better coverage; less paint needed)
• Better pigment particles (smaller, more uniform)
• Coverage: 350-450 sq ft per gallon (vs 200-300 for cheap)

Why this matters:

• Premium paint with 1 coat = cheap paint with 2-3 coats
• Labor cost dominates total job; better paint = less labor
• Better paint = better final appearance

VOC + environmental

VOC (Volatile Organic Compounds):

• VOCs evaporate during cure; contribute to smog + indoor air pollution
• Regulated:
  • California's SCAQMD: max 50 g/L most latex
  • Many states: max 100 g/L
  • "Zero-VOC" = < 5 g/L

Allergen-friendly / low-emission:

• Greenguard Gold certification
• Important for: hospitals, schools, sensitive customers

Additive specifics

Mildewcides:

• Added for bath, kitchen, exterior
• Modern: copper-based (no longer using arsenic, etc.)

Anti-fouling:

• Coastal exterior paints - resist salt deposit

Insecticide-additive:

• Some premium exterior paints
• Repels termites, ants near foundation

Paint storage

Latex/acrylic:

• 1-2 year shelf life unopened
• 6-12 months once opened (well-sealed)
• Don't freeze
• Store in moderate temperature

Oil-based:

• 2-5 year shelf life unopened
• Once opened: 6-12 months
• Store away from heat (flammable solvent)

Disposal:

• Latex: latex hardens; dispose dry in trash
• Oil: hazardous waste; municipal hazardous-waste site
• Empty cans: recyclable if clean

Common chemistry mistakes

• Latex over oil without prep: latex peels off oil unless surface is sanded + primed
• Oil over latex: usually OK after sanding
• Wrong primer for the topcoat: paint won't bond
• Stain bleeding through latex topcoat: wrong primer (need oil or shellac for water/tannin stains)
• Painting cold: latex below 50°F won't cure properly
• Painting hot: > 90°F dries too fast, doesn't bond well
• Painting humid: > 85% humidity slows cure, can blister

References

• Paint manufacturer technical data sheets
• ASTM paint standards
• EPA VOC regulations
• Manuall internal: Interior Painting Process SOP, Exterior Painting Process SOP, Surface Prep for Painting