Painting a Vehicle — Tips & Tricks
Must-read tips, mix ratios, and spray gun settings before you start your project
Download the Cheat Sheet
All the steps, mix ratios, and spray gun settings on one handy reference card. Thousands of painters keep this pinned in their garage. Download the PDF free or order a paper copy shipped with your next order.
Mix Ratios — Quick Reference
AP-7541 DTM Primer (Sealer): 4:1:2 — AP-7541 : AH-7105 Activator : AR-30XX Reducer
AP-7541 DTM Primer (High Build): 4:1:1 — AP-7541 : AH-7105 Activator : AR-30XX Reducer
AP-5511 Epoxy Primer: 1:1:20% — AP-5511 : AH-6100 : AR-30XX Reducer
Alpha Basecoat: All basecoats come "Ready To Spray" in our paint kits - so no need to further reduce or activate!
IF SPECIFICALLY ORDERED NON_REDUCED: 1:1 — Basecoat : AR-30XX Reducer (e.g. 1 qt basecoat : 1 qt reducer)
AC-4521 HS Glamour Clearcoat: 2:1 — AC-4521 : AH-71XX Activator (7103, 7105, or 7107). Can reduce up to 10% with AR-30XX if too thick for your spray style.
Reducer Speed Guide — Match Your Temperature
Choosing the right reducer speed for your environment is make or break for your project's final finish and longevity.
Thats why our paint kits make it easy and Auto-choose them based on your project!
AR-3060 (Fast): Below 65°F — fast airflow environments, small repairs
AR-3070 (Medium): 65–80°F — general purpose, most common
AR-3080 (Slow): 80–90°F — full panels, warmer shops
AR-3090 (Extra Slow): 90°F+ — low airflow, hot environments, full vehicles
Most projects are sprayed in 71–90°F. When in doubt, go one speed slower to avoid solvent pop and orange peel.
Spray Gun Settings & Technique
Nozzle/Tip Sizes:
• Basecoat: 1.3–1.4mm
• Clearcoat: 1.3–1.4mm (set at 30–40 PSI)
• Primer/Sealer: 1.4–1.8mm (set at 25–30 PSI)
• High-Build Primer: 1.8–2.0mm (set at 20–25 PSI)
Air Pressure:
• HVLP at the cap: 26–29 PSI
• At the wall/regulator: 40–50 PSI (varies by gun and hose length)
• Always measure at the cap, not the compressor. Cap pressure is typically 5–10 PSI lower than regulator
Technique:
• Distance: 6–8 inches from surface
• Speed: approximately 1 foot per second
• Overlap: 50–75% per pass
• Keep the gun perpendicular to the surface
• Start moving before pulling the trigger, release after passing the edge
Compressor Requirements:
• Minimum: 12+ CFM at 40 PSI, 60 gallon tank (30 gallon bare minimum for panels only)
• Must have: moisture separator, desiccant dryer, regulator with water trap
• Drain the tank after every use
Prep Tips — Get This Right and the Rest Is Easy
Surface Prep:
• Always use wax & grease remover before AND after sanding
• Block sand in one direction, not circles
• Use 320 grit for final sand before primer on exterior panels
• Scuff door jambs, engine bay, and intricate areas with a red scuff pad
• Blow off all dust OUTSIDE your paint area, then wipe down with anti-static wax & grease remover
Body Work:
• TrueFill Polyester Filler: mix 2% hardener by weight — you have 6–7 minutes of working time
• Apply in several thin layers, max 3mm total
• Shape with P80–P120, finish with P120–P280
• After body work, always prime before painting
Block Sanding:
• Rigid blocks for flat panels
• Semi-flex blocks for contours
• Ultra-flex blocks for complex curves
• Linear Blocks give the best results for blocking primer
Basecoat & Clearcoat Tips
Basecoat Application:
• Choose the Ready To Spray reducer matched to your temperature youll be spraying in! Thats why our paint kits make it easy and Auto-choose them based on your project!
• Spray 2–4 medium wet coats (most colors need 3 for full coverage)
• Flash time: 5–15 minutes between coats — wait until the surface turns matte
• Final coat should be a "control coat" — lighter to lay down even
• Can denib with 600 grit between coats (wipe clean and recoat)
• 8-Hour Rule: If basecoat sits uncoated for 8+ hours, scuff with 600–800 grit before clearcoat
Clearcoat Application (AC-4521):
• Mix 2:1 — clearcoat to activator. No reducer needed (can add up to 10% if too thick)
• Spray 2–3 full wet coats
• Recoat when the previous coat is "fingerprinting" when you touch the overspray on your masking
• Flash time: 8–10 minutes between coats
• Check your masking for overspray buildup between coats
• Let cure 12 hours minimum in a warm (70°F+) ventilated area with a fan running to evacuate solvents
Wait 45 minutes after the final basecoat is 100% dry before applying clearcoat.
Wet Sanding & Polishing
Wait Times Before Sanding:
• AC-4521 HS Glamour: 12 hours minimum
Process:
1. 1500 grit wet — level orange peel (horizontal strokes until uniformly flat/matte)
2. 2000 grit wet — refine scratches (vertical/90° to previous direction until uniform haze)
3. 3000 grit wet — optional but recommended (horizontal again)
4. Cutting compound with DA polisher (medium speed, small sections at a time)
5. Finishing polish (finishing pad, remove micro-swirls)
Warnings:
• Don't sand too soon — it gums up and causes deep scratches
• Watch edges — clearcoat is thinnest there. If you see color on your sandpaper, STOP immediately
• Don't skip grits
• Never let the surface go dry during wet sanding
• Keep polishing pads clean
Common Mistakes & Troubleshooting
Orange Peel: Gun too far, pressure too low, paint too thick, wrong reducer speed. Fix: wet sand 1500–2000 grit, compound, polish.
Fisheyes / Craters: Silicone, wax, grease, oil, contaminated air. Fix: must sand back completely (600-800 grit), clean, and repaint. Cannot be buffed out. Prevent: use wax & grease remover before every step, moisture separator on air line, no silicone products near spray area.
Solvent Pop / Pinholes: Coats too heavy, not enough flash time, reducer too fast, high humidity. Fix: wet sand 600, reapply clear in thinner coats or with proper dry times. Prevent: medium wet coats, full flash time, correct reducer speed.
Runs & Sags: Too much paint, gun too close, moving too slowly. Fix: let cure, razor blade, wet sand 1500–2000, compound/polish. Prevent: steady pace, 6–8 inches, thin coats.
Peeling / Delamination: Poor prep, skipped primer, trapped moisture. Fix: strip to solid layer, re-prep, repaint from primer up. Prevent: always use Alpha primer, sand between stages, follow TDS recoat windows.
Technical Data Sheets (TDS) — Car Kit Products
Read the TDS for every product before starting your project. These sheets have the exact mix ratios, dry times, recoat windows, and application specs.
Primers:
• AP-7541 DTM Primer/Sealer TDS
• AP-5511 HS Epoxy Primer/Sealer TDS
Basecoats:
• Alpha Basecoat TDS (Custom, OEMatch, OEMatch+)
Clearcoats:
• AC-4521 HS Glamour Clearcoat TDS
Other Products:
• Spray Glaze TDS
• TrueFill Polyester Body Filler TDS
Full TDS hub: thespraysource.com/pages/tds
Frequently Asked Questions
How much paint do I need?
Our kits are pre-measured for your vehicle size. Motorcycle/bike: 1–2 quarts basecoat. Small car: 3–4 quarts. Medium car: 4–5 quarts. Large car/truck: 5–8 quarts. Single panel: 1 pint to 1 quart. When in doubt, always size UP — more product is much better than running out mid-project.
What's included in a car paint kit?
Every kit includes: AP-7541 DTM Primer/Sealer, your chosen basecoat color, urethane reducer matched to your spray temperature, activator/hardener for primer and clearcoat, Alpha 2K clearcoat, and step-by-step instructions. 3-stage colors also include the correct undercoat. Optional add-ons: masking tape/paper, body filler, spray glaze, OptiGrit sandpaper, scuff pads, wax & grease remover, tack cloths.
What's the mix ratio for the DTM primer in my kit?
As a sealer (most common for kits): 4:1:2 — 4 parts AP-7541, 1 part AH-7105 activator, 2 parts AR-30XX reducer. Use a 1.4mm needle at 25–30 PSI. Spray 1 medium wet coat, wet-on-wet. Topcoat in 15–20 minutes.
As high build: 4:1:1 — same but less reducer. Use a 1.8–2.0mm needle at 20–25 PSI. Spray 3–4 coats. Must sand after 3 hours if not topcoated.
What's the mix ratio for basecoat?
1:1 — equal parts basecoat to Alpha Urethane Reducer. Example: 1 quart basecoat + 1 quart AR-30XX reducer. Choose reducer speed based on your spray temperature: AR-3060 (Fast, below 65°F), AR-3070 (Medium, 65–80°F), AR-3080 (Slow, 80–90°F), AR-3090 (Extra Slow, 90°F+).
What's the mix ratio for AC-4521 clearcoat?
2:1 — 2 parts AC-4521 clearcoat to 1 part AH-71XX activator. Choose activator by temperature: AH-7103 (Fast, 55–70°F), AH-7105 (Medium, 70–85°F), AH-7107 (Slow, 85–95°F+). No reducer needed, but you can add up to 10% AR-30XX if it's too thick for your spray style. Pot life is 1 hour at 68°F, so only mix what you can spray in that window.
How long do I wait between basecoat and clearcoat?
After your final basecoat is 100% dry to the touch (no wet areas anywhere), wait 45 minutes before spraying clearcoat. Important 8-Hour Rule: If basecoat sits uncoated for more than 8 hours, you must scuff with 600–800 grit before applying clearcoat.
How long between clearcoat coats?
Recoat when the previous coat is "fingerprinting" — meaning when you touch the overspray on your masking tape and it leaves a fingerprint. This is typically 8–10 minutes. Spray 2–3 full wet coats total.
What temperature should I paint in?
Ideal painting temperature is 65–85°F. Most projects are sprayed in 71–90°F. The temperature determines which reducer and activator speed you need. Don't spray below 55°F. Avoid painting in direct sunlight or above 80% humidity.
Do I need a spray gun? What kind?
Yes, you need an HVLP spray gun with a 1.3–1.4mm nozzle for basecoat and clearcoat. For high-build primer, use a 1.8–2.0mm nozzle. You also need an air compressor: 12+ CFM at 40 PSI with at least a 60 gallon tank (30 gallon bare minimum for panels only). Must have a moisture separator, desiccant dryer, and regulator with water trap. Drain the tank after every use.
I got fisheyes / craters in my paint — what happened?
Fisheyes are caused by silicone, wax, grease, oil, or contaminated air. They CANNOT be buffed out. You must sand back completely with 800–1200 grit, clean thoroughly, and repaint. Prevention: use wax & grease remover before every step, install a moisture separator on your air line, and keep all silicone-based products far from your spray area.
My clearcoat has orange peel — can I fix it?
Yes. Wait 12 hours for AC-4521 to fully cure, then wet sand with 1500 grit (horizontal strokes until uniformly flat), then 2000 grit (vertical, 90° to previous direction), optionally 3000 grit, then compound with a DA polisher, and finish with a finishing polish. Watch the edges — clearcoat is thinnest there. If you see color on your sandpaper, stop immediately.
What's the difference between Metal Up, Light Body Work, and Scuff & Shoot?
Metal Up: Stripped to bare metal and restored from scratch — full primer, sealer, basecoat, clearcoat. Light Body Work: Vehicle is overall in good shape but has some areas needing filler and spot priming. Scuff & Shoot: Vehicle is in mint condition or it's a budget build — just scuff the existing finish and paint over it. No body work or heavy primer needed.
Should I order a painted sample first?
Highly recommended. Painted samples are $11.99 each (buy 3 = 10% off, buy 6 = 20% off). Seeing the color in person under different lighting and angles will make you 100% sure before buying a full kit. We offer a prepaid return label for $6.99. ALL OEM colors should be blended into surrounding panels since your original paint has aged/faded.
Can I use a spray can instead of a spray gun?
Yes — we offer the same Alpha formulas in aerosol cans. Great for wheels, bumpers, panels, helmets, and RC cars. Shake vigorously for 2+ minutes, spray 8–10 inches away, 3–4 light/medium coats with 5–10 min flash. Our 2K clearcoat cans have a 24–48 hour pot life after activation. You can wet sand and polish spray can clear just like spray gun application.
Ready to Start Your Project?
Call or text us at 508-316-9868 — we'll help you pick the right kit
