Primer

Primer is a preparatory coating applied to metal or body filler before paint. It serves multiple critical functions: adhesion (helps paint stick), protection (seals metal from moisture), and surface preparation (fills minor imperfections).

There isn't just one "primer"—there are multiple types used in sequence:

1. Etching Primer (Self-Etching Primer)

• First layer on bare metal

• Chemically bonds to metal through acid etching

• Provides corrosion resistance

• Very thin (2–3 coats maximum)

• Must be top-coated within 24–48 hours

2. Epoxy Primer

• Excellent adhesion and sealing

• Can go directly on bare metal or over etching primer

• Superior moisture protection

• Can be top-coated after hours or months

• My personal favorite for bare metal

3. High-Build Primer (Primer-Surfacer)

• Thick primer that fills minor imperfections

• Sands easily for smooth surface

• Applied over epoxy or etching primer

• Multiple coats (2–6) depending on bodywork quality

• This is what you block-sand to perfection

4. Sealer

• Final primer layer before paint

• Provides uniform color base for paint

• Improves paint adhesion

• Prevents "sand scratch swelling"

• Optional but recommended for show work

I learned the hard way that skipping epoxy primer and going straight to high-build costs money later. My first paint job (done cheap) started showing rust bloom through the paint after 18 months. The "painter" had skipped epoxy on the bare metal floor pans. Moisture got under the paint, rust started, paint blistered. Had to strip it all and start over—this time with proper epoxy primer. That lesson cost $8,000.

Primer is where paint jobs succeed or fail long-term:

Proper primer system:

• Protects bare metal from rust

• Provides paint adhesion

• Fills minor surface imperfections

• Creates uniform surface for paint

• Extends paint life 2-3x

Skipped or cheap primer:

• Rust starts under paint within months/years

• Paint adhesion fails (peeling, flaking)

• Surface imperfections telegraph through paint

• Complete paint failure requires expensive do-over

The timeline truth:

You won't know if your primer system was done right for 1–3 years. By then, the "cheap" shop that skipped steps is long gone, and you're paying someone else to fix it.

Cost of doing it right vs. wrong:

• Proper primer system: $800–$2,000 in materials and labor

• Fixing failed paint from bad primer: $8,000–$15,000 (complete strip and repaint)

Spending $1,500 on proper primer is insurance against throwing away $15,000 later.