Use a Guide Coat to Level Primer: 220–400 Grit Workflow (No Low Spots)

Uneven primer hides waves that will telegraph through paint. A guide coat shows highs and lows instantly so you can sand flat—fast—without burning edges. This workflow uses a tight grit sequence and simple checkpoints to guarantee a smooth, basecoat-ready surface.

Before You Start

• Primer must be fully cured; if paper gums up, wait longer.
• Work under bright, indirect light. Clean dust often so you can read the surface.
• Use a soft foam interface pad on curves to keep pressure even.

Grit Progression

• 220 grit — first leveling pass after the guide coat reveals highs/lows.
• 320 grit — refine scratches and tighten flatness.
• 400 grit — pre-paint finish so base lays down smooth.

Step-by-Step

1. Apply a guide coat. Lightly dust a contrasting powder or rattle-can mist over the primer. It should look speckled, not painted.
2. Level at 220. Wrap the sheet on a foam pad. Sand in straight, overlapping passes. High spots clear first; low spots stay dark—keep going until the guide coat is gone uniformly.
3. Re-coat and check. Add another light guide coat. If any islands remain after a few strokes, they’re still low; continue at 220 locally until they fade.
4. Refine at 320. Change stroke direction (e.g., left–right to front–back) to reveal leftover 220 scratches. Rinse/wipe often.
5. Finish at 400. Quick passes for a tight, even haze. No visible lines under a raking light.
6. Clean for paint. Vacuum, tack, and proceed to basecoat per your system’s window.

Pro Tips

• Mask edges and body lines—clear and primer are thinnest there.
• Fresh paper cuts flatter; dull sheets skate and create random scratches.
• Dedicated pad per grit to avoid cross-contamination.

What to Buy

Start the cut with Grit 220 — 10 Pack, refine flatness using Grit 320 — 50 Pack, then create a paint-ready haze with Grit 400 — 10 Pack.

Watch & Learn

Result: A uniformly leveled primer surface with no telegraphed lows—ready for base and clear.