Spray Painting Technique

Goal

Apply paint via airless sprayer with professional quality + efficiency. Spraying is 5-10x faster than brushing on large surfaces - but only if technique is right. Wrong technique = waste paint, uneven coverage, runs, overspray damage.

When to spray vs brush/roll

Spray:

• Large exterior areas (siding, fences)
• Cabinets + doors (factory-like finish)
• Spray + back-roll for exterior maximum bond
• New construction interior (mass production)

Brush/Roll:

• Single-room interior (no need for sprayer setup)
• Detail work (trim, windows)
• Touch-ups
• Cost-sensitive jobs where setup time > spray time

Equipment essentials

Airless sprayer:

• 1+ HP for residential, 3+ HP for heavy commercial
• Pressure adjustable
• Hose length (50-100 ft typical)
• Spray gun (in-line filter, swivel)

Spray tips:

• Numbered with 3 digits (e.g., 515 = 5-inch fan width × 0.015" orifice)
• Match to paint:
  • Stains, lacquers, thin paints: 0.009-0.013
  • Latex, thin paints: 0.013-0.015
  • Thick latex, masonry: 0.017-0.021
  • Block fillers, heavy coatings: 0.023+
• Worn tip = uneven pattern = replace

Filters:

• In-line filter (gun): keeps debris from tip
• Suction filter (intake): keeps paint clean
• Clean both daily

Other:

• Hose (3/8" most common)
• Pressure release valve
• 5-gallon bucket strainer (filters debris)

Spray gun technique

Distance: 10-14 inches from surface

• Too close (< 10"): heavy build-up, runs
• Too far (> 14"): overspray, thin coverage
• Maintain consistent distance throughout pass

Speed: consistent, smooth

• Move arm at walking pace (~1 sec per 12-18 inches)
• Slower = thicker
• Inconsistent speed = inconsistent finish

Direction: always start moving BEFORE pulling trigger; release trigger BEFORE stopping

• Prevents heavy buildup at start + end of each pass
• Trigger control = start with trigger off; depress AFTER motion begins; release BEFORE motion stops

Overlap: each pass overlaps previous by 50%

• Top-half of new pass covers bottom-half of previous
• Without overlap: striping
• Too much overlap (75%): paint waste + drips

Pattern:

• Cross-hatch: vertical first pass, horizontal second pass
• Same pass: not as good (parallel striping risk)

Setting up a job

Step 1: Mask + protect

• Cover all surfaces NOT being painted (overspray travels 6-10 ft)
• Plastic + tape on adjacent surfaces
• Plant cover for exterior
• Vehicle covers
• HVAC condenser covers

Step 2: Strain + prepare paint

• Stir paint thoroughly (premium paints can settle)
• Strain through 200-mesh bag into 5-gallon bucket
• Removes lumps that would clog tip

Step 3: Prime sprayer

• Connect intake to paint, return to bucket
• Pressure to low
• Cycle paint until pure paint exits return line (no air)
• Switch return to spray

Step 4: Test pattern

• Set pressure to manufacturer spec
• Spray test pattern on cardboard or scrap
• Adjust:
  • Striping in middle = pressure too low OR tip worn
  • Tail-like pattern = pressure too low OR wrong tip
  • Heavy in center = pressure too high

Step 5: Begin work

• Start at top, work down (drips run off completed work)
• Work in sections you can complete with one tip-pressure setting
• Refill paint before tank runs dry (avoids air ingestion)

Common spray problems + fixes

Fingers / Tails:

• Pattern has thicker edges or tails
• Cause: pressure too low, worn tip
• Fix: increase pressure 100-300 psi OR replace tip

Heavy spitting:

• Paint comes out in chunks
• Cause: clogged tip OR debris
• Fix: clean tip (reverse-flow back-flush) OR replace

Overspray drift:

• Paint reaches surfaces you didn't intend
• Cause: too much pressure, wind, too thin tip
• Fix: reduce pressure, work without wind, larger tip

Cobwebbing (stringy spray):

• Paint comes out in long strings
• Cause: pressure too low, viscosity too high
• Fix: increase pressure, thin paint, or use larger tip

Sags + runs:

• Paint drips on surface
• Cause: too much paint per pass, too slow speed
• Fix: faster motion, more passes vs one heavy

Back-rolling / back-brushing

After spray, immediately roll OR brush the surface:

• Spray + back-roll (exterior, masonry): forces paint into texture, better penetration
• Spray + back-brush (wood siding, fascia): forces paint into wood grain
• Reduces overspray waste
• Increases adhesion 20-30%

For exterior reroofing, this is the standard.

Cleanup

Important: clean within 30 minutes of last spray

1. Flush hose with cleaning solution (water for latex, mineral spirits for oil)
2. Cycle clean liquid until clear
3. Disassemble gun + clean tip
4. Reverse-flush filters
5. Store with anti-corrosion (mineral spirits + lubricant)

Sprayer left with paint in it for hours = damaged + expensive repair.

Safety considerations

• Eye protection: spray comes back; safety glasses always
• Respirator: especially with oil-based or solvent paints
• Skin contact: nitrile gloves; long sleeves recommended
• High-pressure injection: pressurized paint into skin is a medical emergency; never put finger in spray path
• Ladder safety: spraying off ladder = unstable; harness essential

Paint choice for spraying

• Latex/acrylic: easy to spray; most modern jobs
• Oil-based: requires solvent cleanup; check sprayer compatibility
• High-build coatings (elastomeric): need larger tip, more pressure
• Stains: thin viscosity, small tip
• Lacquers: difficult; usually HVLP territory

When NOT to spray

• High wind exterior (> 10 mph)
• Adjacent surfaces can't be protected
• Single-room interior touch-up
• Detail work
• Customer present + worried about overspray (chemical-sensitive)

References

• Manufacturer sprayer manuals (Graco, Titan, Wagner)
• PCA spray application standards
• Manuall internal: Paint Types + Chemistry Reference