Planning a Paint Job: Prep, Primer, Base and Clear

A good paint job is about 80 percent preparation. This guide lays out the stages from stripping and bodywork to primer, color and clear, gives typical quantities and sanding grits, and lists the defects to watch for.

Choose the system first

Your options affect the materials you buy, the number of steps and the finish you get.

System	How it works	Best for
Single-stage	Color and gloss in one coat, no clear	Work vehicles, older cars, budget jobs
Basecoat/clearcoat	Color layer then a protective clear layer	Modern finishes, metallics, show quality
Powder coat	Dry powder baked to cure	Wheels, frames, brackets
Rattle can or roller	Consumer-grade application	Small parts, temporary finishes

The Paint & Finish System Finder asks a few questions and recommends a system for your car, budget and skill.

Prepare the surface

Strip or sand to a sound base. Remove failing paint, treat rust properly by cutting it out or converting it rather than painting over it, and clean the panel with a wax and grease remover. Mask carefully and remove trim where you can. Any flaw that you leave will show through the final finish.

Bodywork and filler

Fill dents with the thinnest layer of filler that does the job. Mix hardener to the maker's ratio, spread it in thin coats and shape it with coarse paper, around 80 grit, then refine it. Use a guide coat, a light dusting of contrasting powder or spray, to show low spots. Estimating quantities of filler and primer is the job of the Body Filler & Primer Calculator.

A typical sanding sequence

Stage	Typical grit
Strip and shape filler	40 to 80
Feather edges and refine filler	120 to 180
Before high-build primer	180 to 220
After primer, before base	320 to 400 (wet or dry)
Single-stage color prep	400 to 600
Color sanding the clear (optional)	1,500 to 3,000, then polish

Always follow the paint maker's technical data sheet. Different products specify their own grits, and mixing a system can void their guidance.

Primer

Use an epoxy primer over bare metal for corrosion protection and adhesion, then high-build primer-surfacer to level small imperfections. Apply two or three coats, allow it to flash and cure as specified, and block-sand with a long, flat block so you do not wave the panel. Seal the surface before base if the data sheet calls for it.

How much paint to buy

Quantities depend on panel area, color, number of coats, spray gun efficiency and the mix ratio. As a rough guide, a mid-size car needs about one to one and a half gallons of sprayable (mixed) basecoat and a similar amount of clear, less for a small car and more for a truck or van. Dark colors cover well; reds, yellows and some pearls need more coats over a suitable sealer color. Interior and jambs add roughly 25 percent. Remember that the figure on the can is for unmixed product, and reducers and activators add to the volume. The Auto Paint Calculator works out what to buy for your vehicle size, coats and system.

Spraying basics

Check gun setup, air pressure at the gun inlet and fluid tip size recommended by the paint maker.
Practice on a spare panel to set your overlap, usually 50 to 75 percent, and your distance.
Respect flash times between coats; coating too soon traps solvents and can cause dieback or solvent pop.
Keep the work area clean, well lit and with airflow that draws overspray away from the car.
Wear a fresh-air or properly fitted organic vapor respirator, eye protection and gloves. Isocyanate hardeners in clear coats are particularly hazardous.

Common defects and causes

Defect	Typical cause
Orange peel	Gun too far, wrong reducer, too thin or too thick coat
Runs and sags	Too much material, too little flash time
Fisheyes	Silicone or oil contamination
Dry spray	Gun too far away, too fast reducer
Solvent pop	Coats too heavy or flashed too briefly
Sand scratches showing	Primer or prep grit too coarse

Curing and finishing

Allow the paint to cure fully before polishing; this can take days or weeks depending on the product and temperature. Wet-sand to remove defects, then buff with compound and polish. Wait the recommended time before waxing, since fresh paint needs to breathe.

Common mistakes

Skipping prep and hoping the paint will hide it.
Mixing products from different systems.
Buying too little and running out before the final coats; color batches can differ.
Painting in cold or humid conditions outside the product's limits.

Frequently asked questions

How much paint does a car need?

A typical mid-size car needs roughly one to one and a half gallons of sprayable basecoat and a similar amount of clear, plus extra for jambs and the interior. The exact figure depends on the color, number of coats and the product's mix ratio.

What grit should I sand before painting?

Before primer, most guides use 180 to 220 grit. After priming and before basecoat, 320 to 400 grit is common. Always check the technical data sheet for your paint.

Is single-stage paint still a good choice?

Yes for work trucks, restorations of period finishes and budget jobs. It is simpler and cheaper, but it lacks the depth and protection of a basecoat and clearcoat system and is harder to repair invisibly.

Tools used in this guide

More guides

Figures in this guide are general guidance for planning. Always follow your vehicle, tool and product manufacturers' instructions and local codes, and read our disclaimer.