Module 2 of 4

Strip, Sand & Featheredge

[VISUAL PLACEHOLDER] Module 2 banner: DA sander featheredging a repair, grit progression laid out.

STRIP, SAND & FEATHEREDGE (The 30-second Lesson Overview)

Remove the finishSand, grind, or chemically strip old paint when needed. Stripper is caustic, so respect the hazards.
SandCoarse to fine. Cut and shape with coarser grit, then step up so the final scratch will be hidden.
FeatheredgeTaper the edges of each paint layer so the repair has no step. Keep each layer at least ~1/2 inch wide.
Block sandUse a block and a guide coat to find highs and lows and get the primer truly flat.
Goal: remove finish safely, sand with the right grit progression, featheredge so repairs do not telegraph, and block sand flat.
๐Ÿ’ก Did you know? Sandpaper grit numbers come from a screen: a P80 abrasive is graded through a mesh with about 80 openings per inch, and P400 through about 400. Higher number means more, finer particles, so a smaller scratch.
!

Safety first

The skills

Sandpaper & Grits: Which Grit, and When

The big idea: abrasives are numbered by grit. A lower number means coarser (bigger, fewer cutting particles that remove material fast but leave deep scratches). A higher number means finer (smaller, denser particles that leave shallow scratches). In a refinish job you always work coarse to fine, stepping up through the grits so each step erases the scratches from the one before. Never jump straight from a coarse grit to paint, the deep scratches will swell and telegraph through the finish.
โš  Follow the product's TDS first
This ladder is a general guide. The exact grit for each step, and whether to sand it wet or dry, comes from the Technical Data Sheet (TDS) of the primer, sealer, filler, or paint you are about to apply. Different product systems call for different grits, so when the TDS differs from this chart, follow the TDS.
Rule of thumb: the closer you get to color and clear, the finer the grit. Coarse grits shape and strip; fine grits prepare a surface to bond and to shine. Always finish at a grit fine enough for the coating you are about to apply.

The Grit Ladder: Coarse to Fine

Each round badge is a sanding disc. Coarse is at the top, fine at the bottom.
36
Heavy Grinding
Cutting welds and removing heavy rust or old coatings down to bare metal.
80
Strip & Rough Cut
Stripping paint to bare metal and rough-shaping body filler.
120
Shape Filler
Knocking body filler down close to the panel's contour.
150
Level Filler
Leveling the filler and starting to taper the paint edges.
180
Featheredge
Cutting the broken paint edges into a smooth taper.
220
Refine the Edge
Refining the featheredge and scuffing the surrounding area.
320
Primer Prep
A common feather-finish grit; scuffing so primer-surfacer grips.
400
Block the Primer
Block sanding the primer-surfacer flat with a guide coat (usually dry).
500
Sealer Prep
Final primer and sealer prep, dry scuff.
600
Pre-Paint Scuff
Scuffing right before basecoat, often done wet.
800
Denib
Knocking down dirt nibs and wet-prepping for some basecoats.
1000
Color Sand Clear
Cutting dirt nibs and runs out of fresh clearcoat (wet).
1200
Level the Clear
Color sanding the clear toward a uniform flat (wet).
1500
Pre-Buff
Leveling the clear before compounding (wet).
2000
Fine Color Sand
Removing fine texture and orange peel (wet).
3000
Final Polish Prep
Ultra-fine sanding right before machine polishing (wet).

Coarse vs Fine: Why More Scratches Grip Better

Adhesion is mechanical. When you scuff a surface, the coating flows into the scratches and locks around the tiny peaks, like thousands of little teeth. It is not about how deep the scratches are, it is about how many anchoring points the coating has to grab.
Coarse grit
Deeper but fewer, wider scratches. Fewer peaks for the coating to lock into, and it mostly contacts the tops. Cuts material fast, but it is not the best surface for a coating to grip.
Fine grit
Shallower but many more scratches, a dense field of micro-peaks. More teeth, more surface area, and more energy needed to pull the coating off. That means stronger mechanical adhesion.
Bottom line: when you are scuffing to bond (before sealer, basecoat, or clear), finer scratch density usually grips better, even though the scratches are finer. When you are removing material (stripping, shaping filler), coarse is the right tool. Match the grit to the job.
โš  Common Pitfalls
[VISUAL PLACEHOLDER] Three removal methods: DA sanding, grinding, chemical stripping.

Remove the paint finish

ASE Surface Prep Task ยท A6"Remove paint finish as needed."What it means: strip the old coating, by sanding, grinding, blasting, or chemical stripper, when the panel cannot be saved by prepping over it.
Why it matters: Sometimes the old finish has to come off so the repair is sound, but removing more than necessary adds work and corrosion risk. Knowing how much to remove is the skill.
How it's done: Mechanically sand or grind, or chemically strip, only as far as needed, keep tools moving to avoid heat and warpage, then neutralize, clean, and treat the bare metal.
What you need: A DA sander or grinder with the right discs, or chemical stripper with containment, a corrosion treatment, plus a respirator, gloves, eye and hearing protection.
โš  Common Pitfalls
  • Stripping more than you need to; sound, well-adhered factory layers can often stay as a base, and removing everything adds work and corrosion exposure.
  • Letting a DA or grinder build heat and warp a thin panel; keep the tool moving and use the right grit.
  • Using chemical stripper without proper containment and PPE, or leaving stripper residue that later attacks the new finish.
  • Forgetting to neutralize, clean, and then treat the now-bare metal before it flash-rusts.
Key pointsPick the least aggressive method that does the job for that substrate, and keep the metal cool and flat so you do not warp or stretch it. The four ways to remove a finish:
  • Mechanical โ€” DA sander or grinder
  • Media blasting
  • Soda blasting
  • Chemical stripper
Tools & supplies6-inch dual-action (DA) sander with a soft interface pad, high-speed grinder/disc sander for heavy material, media or soda blaster, chemical (aircraft) stripper with a plastic scraper, sanding blocks, dust extraction or a vacuum, and PPE: particulate respirator, gloves, eye and ear protection.
Grits & methodsOn a DA: 36-grit removes all coatings fast, 40-grit removes all coatings, then 80-grit to shape any filler and 180-grit to take out the 80-grit scratches. Grinder discs (zirconia/aluminum oxide) for weld beads and heavy rust. Media/soda blasting takes coating to bare metal with no sanding heat, good for thin panels that warp. Chemical aircraft stripper makes no dust but burns skin, gives off toxic fumes, and leaves hazardous runoff. (Verify grits and products on the abrasive and stripper data sheets.)
Technique & best practiceKeep the DA flat at a low angle with a soft pad and let the tool cut; do not lean on it. Avoid heat and aggressive grinding on thin or aluminum panels. Never use discs on aluminum that were used on steel, the cross-contamination starts corrosion. Bare metal flash-rusts, so treat and prime it the same day.
How to Do It (Step by Step)
  1. Choose the method for the substrate (mechanical for most steel, blasting for warp-prone panels, chemical where heat is a problem).
  2. For DA removal, cut the coating with 36 to 40 grit, then shape filler with 80 and clean up the scratches with 180.
  3. If chemical stripping, mask surrounding areas, apply per the label, let it dwell, scrape, then neutralize and capture the runoff as hazardous waste.
  4. Keep the panel flat and cool; check often so you do not grind through good metal.
  5. Treat and prime any bare metal promptly.
๐ŸŽฌ Video demo + narration
Film this procedure (or build a narrated slideshow from the step images). Save as ase_b2a_demo_demo.mp4 in this category's images folder, then swap this box for a <video> player.
Narration script (read in order):
  1. Choose the method for the substrate (mechanical for most steel, blasting for warp-prone panels, chemical where heat is a problem).
  2. For DA removal, cut the coating with 36 to 40 grit, then shape filler with 80 and clean up the scratches with 180.
  3. If chemical stripping, mask surrounding areas, apply per the label, let it dwell, scrape, then neutralize and capture the runoff as hazardous waste.
  4. Keep the panel flat and cool; check often so you do not grind through good metal.
  5. Treat and prime any bare metal promptly.
๐Ÿ“ท Step-by-step image prompts โ€” consistent series (generate in one session; reuse the same subject/style reference so every step matches)
Step 1 โ€” save as ase_b2a_step_s11.jpg: Create an image showing this exact step in an automotive refinishing lesson: Choose the method for the substrate (mechanical for most steel, blasting for warp-prone panels, chemical where heat is a problem). CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 2 โ€” save as ase_b2a_step_s21.jpg: Create an image showing this exact step in an automotive refinishing lesson: For DA removal, cut the coating with 36 to 40 grit, then shape filler with 80 and clean up the scratches with 180. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 3 โ€” save as ase_b2a_step_s31.jpg: Create an image showing this exact step in an automotive refinishing lesson: If chemical stripping, mask surrounding areas, apply per the label, let it dwell, scrape, then neutralize and capture the runoff as hazardous waste. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 4 โ€” save as ase_b2a_step_s41.jpg: Create an image showing this exact step in an automotive refinishing lesson: Keep the panel flat and cool; check often so you do not grind through good metal. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 5 โ€” save as ase_b2a_step_s51.jpg: Create an image showing this exact step in an automotive refinishing lesson: Treat and prime any bare metal promptly. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.

Remember: Match the method to the substrate. 36 to 40 grit strips fast; keep the DA flat, the metal cool, and prime bare metal the same day.

Removing the Finish: 4 Methods Compared

There is more than one way to take a finish off. The right choice depends on the substrate, how much you are removing, the size and shape of the area, and what equipment you have. Here are the four main methods, side by side.
๐ŸŒ€ Mechanical (Sanding & Grinding)
How it works: Abrasive discs on a DA sander or grinder cut the coating off.
Best for: Most everyday spot and panel repairs, and any area where you are also working body filler.
Why: Fast, controllable, and cheap, with no special equipment. You can stop exactly where you want.
The catch: Builds heat and can warp thin panels if you lean on it or stay in one spot. It makes dust, so contain it and wear protection.
๐Ÿงช Chemical Stripping
How it works: A chemical stripper is brushed on and lifts the coating so it can be scraped off.
Best for: Large areas or intricate, contoured parts where you want many layers off without heat.
Why: No heat means no warpage, and it reaches shapes a sander cannot.
The catch: It is caustic and hazardous, with fumes, skin burns, and hazardous waste. It can seep into seams and behind panels, and you must neutralize and clean thoroughly before refinishing.
๐Ÿ’จ Media / Sand Blasting
How it works: Abrasive media (sand, glass bead, garnet, plastic, or baking soda) is blasted at the surface under air pressure to strip coating and rust.
Best for: Heavy rust and scale, frames, and removable or complex parts, especially in restoration work.
Why: Very fast on rust, reaches recesses, and uses no chemicals. Softer media like soda or plastic is gentle enough for thin panels.
The catch: Aggressive media can warp or work-harden thin sheet metal and build heat. Media has to be contained and cleaned up, can embed in the surface, and silica sand is a serious lung hazard, so media choice and PPE matter.
๐Ÿ”ฆ Laser Removal
How it works: A laser vaporizes (ablates) the coating in a controlled beam, layer by layer.
Best for: Precise, selective removal, taking off just the paint while leaving primer or bare metal, or working delicate substrates.
Why: Extremely controlled, with no media or chemicals, almost no waste, and little to no substrate damage or warpage when set correctly.
The catch: The equipment is expensive, it is slower over large areas, it needs fume extraction, and the laser requires eye protection and training. It is still uncommon in general body shops.
Quick pick: spot or panel repair with filler, reach for mechanical. Big or contoured areas with many layers and no heat, chemical. Heavy rust, frames, or removable parts, blasting (match the media to the metal). Precise, selective, or chemical-free work, laser. Whatever you choose, protect the metal from heat and corrosion, and treat any bare metal right away.

๐Ÿ”ง Practice in the Lab: Remove a finish without warping the metal

GoalStrip a panel with a DA sander kept flat and cool, or by chemical stripper, without warping or stretching the metal.
Skill checkCoating is gone to a sound layer, the panel is still flat and cool, and bare metal was treated and primed the same day.
[VISUAL PLACEHOLDER] Grit progression chart: cut grits up to finish grits.

Sand areas to be refinished

ASE Surface Prep Task ยท A7"Dry or wet sand areas to be refinished."What it means: cut and smooth the surface with the right abrasive and grit so the next coat bonds and hides.
Why it matters: Sanding gives the coating a uniform surface and the mechanical bite it needs to stick. Done wrong, the scratches either show through or the paint will not hold.
How it's done: Work through a grit progression suited to the coating, scuff the whole area the clear will cover, and keep the panel flat and clean.
What you need: A DA sander and hand block, aluminum-oxide abrasives in the right grits, scuff pads, plus a respirator and eye protection.
โš  Common Pitfalls
  • Skipping grits (for example P80 straight to primer), which leaves coarse scratches that swell and telegraph through the topcoat.
  • Sanding too coarse for the coating you are about to apply, so the scratch shows through primer or sealer.
  • Sanding through edges and high spots to bare metal and not re-treating those spots.
  • Not scuffing the entire area the clear will cover, leaving glossy spots with no mechanical bite.
Key pointsSand coarse to fine, never skipping more than a grade or two. Coarser grit cuts and shapes; finer grit leaves a scratch small enough for the next coat to fill and hide. The abrasive material matters too: aluminum oxide for general sanding and primer, silicon carbide for wet sanding and paint.
Tools & suppliesDA sander with a soft, thick interface pad, sanding blocks, hand pads and sponges; P-grade (FEPA) paper; and scuff pads matched to the job: red/maroon pad (about 320 to 400 grit) for aggressive scuffing and new parts, gray pad (about 800 to 1000) for blend areas and prepping plastic, white/gold pad (about 1200 to 1500) for light scuffing.
Grits & progressionShape filler at 80-grit, take out the 80 scratches with 180, then step up. Final sand before sealer or basecoat: dry with a DA, P400 is best (P360 acceptable); dry by hand, P500 (or P400); wet by hand or machine, P600 is best (P500 good). Going dry to wet, drop two grades finer because wet cuts more aggressively; going machine to hand, drop one grade finer. (Confirm final grit on the paint maker's data sheet.)
Technique & best practiceSand in one direction, with the length of the panel; circles or cross-strokes leave marks that show and are hard to buff out. Run the DA at a low, flat angle with light pressure and lower speed; high pressure and speed cause rework. Turn the DA speed down near body lines. Clean with wax and grease remover before and after. Wet sand with clean, running water, never dirty bucket water. Use a guide coat so you do not oversand.
How to Do It (Step by Step)
  1. Pick the starting grit for the job: 80 to shape filler, 180 to clean up, finer to scuff for coating.
  2. Step up through the grits in order so each one removes the last one's scratches.
  3. Keep the DA flat and light, sanding with the length of the panel; slow down at body lines.
  4. Keep paper and surface clean; for wet sanding use plenty of clean water.
  5. Finish at the grit your next coat calls for (commonly P400 dry by machine to P600 wet).
๐ŸŽฌ Video demo + narration
Film this procedure (or build a narrated slideshow from the step images). Save as ase_b2a_demo_demo.mp4 in this category's images folder, then swap this box for a <video> player.
Narration script (read in order):
  1. Pick the starting grit for the job: 80 to shape filler, 180 to clean up, finer to scuff for coating.
  2. Step up through the grits in order so each one removes the last one's scratches.
  3. Keep the DA flat and light, sanding with the length of the panel; slow down at body lines.
  4. Keep paper and surface clean; for wet sanding use plenty of clean water.
  5. Finish at the grit your next coat calls for (commonly P400 dry by machine to P600 wet).
๐Ÿ“ท Step-by-step image prompts โ€” consistent series (generate in one session; reuse the same subject/style reference so every step matches)
Step 1 โ€” save as ase_b2a_step_s11.jpg: Create an image showing this exact step in an automotive refinishing lesson: Pick the starting grit for the job: 80 to shape filler, 180 to clean up, finer to scuff for coating. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 2 โ€” save as ase_b2a_step_s21.jpg: Create an image showing this exact step in an automotive refinishing lesson: Step up through the grits in order so each one removes the last one's scratches. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 3 โ€” save as ase_b2a_step_s31.jpg: Create an image showing this exact step in an automotive refinishing lesson: Keep the DA flat and light, sanding with the length of the panel; slow down at body lines. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 4 โ€” save as ase_b2a_step_s41.jpg: Create an image showing this exact step in an automotive refinishing lesson: Keep paper and surface clean; for wet sanding use plenty of clean water. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 5 โ€” save as ase_b2a_step_s51.jpg: Create an image showing this exact step in an automotive refinishing lesson: Finish at the grit your next coat calls for (commonly P400 dry by machine to P600 wet). CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.

Remember: Coarse cuts, fine finishes. Sand with the length of the panel, DA flat and light, and step the grits, do not jump them.

๐Ÿ”ง Practice in the Lab: Grit-progression drill

GoalLay out sandpaper in the correct order for a job and explain why you never skip a grit.
Skill checkYou step coarse to fine in order and finish at the grit the next coat calls for (P400 dry to P600 wet).
[VISUAL PLACEHOLDER] Cross-section of a featheredge: bare metal tapering up through primer and paint.

Featheredge the repair

ASE Surface Prep Task ยท A8"Featheredge areas to be refinished."What it means: taper the broken paint edges around a repair so there is no step to telegraph through the new finish.
Why it matters: A featheredge tapers the paint layers around a repair so there is no step to telegraph through the new finish or become a lift and crack point.
How it's done: Spread each layer into a wide ramp through a grit progression (about 180, then 220, then 320), keep each ring at least about a half inch wide, and check by feel for a smooth taper.
What you need: A DA sander and hand block, aluminum-oxide paper in the grit steps, a guide coat to read it, plus a respirator and eye protection.
โš  Common Pitfalls
  • Skipping grits, so coarse scratches swell and show through the finish.
  • Featheredging too narrow or too steep, so the stacked layers map through as visible rings.
  • Sanding through to bare metal beyond the repair and not re-treating it, inviting corrosion.
  • Finishing with too coarse a grit, so the scratch shows through the primer-surfacer.
  • Not cleaning before you sand, which drags silicone into the fresh scratches.
Key pointsFeatheredging tapers the edges of the paint layers around a repair so there is no visible step. Body filler and the area are first leveled with 150-grit; the featheredge process then refines that edge for primer. Each exposed layer (clear, color, primer, e-coat, bare metal) should show as a ring at least about 1/2 inch wide.
Tools & suppliesPneumatic DA sander or a hand sanding block, aluminum oxide paper, a red scuff pad with water and blend prep, clean compressed air, and a tack rag.
Sandpaper & gritAfter the filler and area are leveled with 150-grit, featheredge with 180-grit, then 220-grit, then 320-grit on a DA or block. 320 is the featheredge finish grit, fine enough to prime over. (This is the industry feather, prime and block sequence; confirm grits against your paint system.)
Technique & best practiceKeep the DA at a low, flat angle with a soft pad, or work by hand on a block, and sand the edges into a long, gradual taper, not a steep cliff. Featheredge slightly larger than the area the primer will cover. Step 180 to 220 to 320 so the last scratch is fine. Scuff the surrounding panel with a red scuff pad and water. Check by dragging a fingernail or a microfiber across it, you should feel no ridge, and look for pinholes.
How to Do It (Step by Step)
  1. Confirm the filler and area are leveled to 150-grit first.
  2. Featheredge the broken paint edges with 180, then 220, then 320 grit, taking each layer out into a wide taper.
  3. Keep each layer of the featheredge at least ~1/2 inch wide so it will not map.
  4. Scuff the surrounding panel, then check by feel and sight; you should not feel a ridge.
  5. Blow off, wipe, and clean before priming.
๐ŸŽฌ Video demo + narration
Film this procedure (or build a narrated slideshow from the step images). Save as ase_b2a_demo_demo.mp4 in this category's images folder, then swap this box for a <video> player.
Narration script (read in order):
  1. Confirm the filler and area are leveled to 150-grit first.
  2. Featheredge the broken paint edges with 180, then 220, then 320 grit, taking each layer out into a wide taper.
  3. Keep each layer of the featheredge at least ~1/2 inch wide so it will not map.
  4. Scuff the surrounding panel, then check by feel and sight; you should not feel a ridge.
  5. Blow off, wipe, and clean before priming.
๐Ÿ“ท Step-by-step image prompts โ€” consistent series (generate in one session; reuse the same subject/style reference so every step matches)
Step 1 โ€” save as ase_b2a_step_s11.jpg: Create an image showing this exact step in an automotive refinishing lesson: Confirm the filler and area are leveled to 150-grit first. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 2 โ€” save as ase_b2a_step_s21.jpg: Create an image showing this exact step in an automotive refinishing lesson: Featheredge the broken paint edges with 180, then 220, then 320 grit, taking each layer out into a wide taper. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 3 โ€” save as ase_b2a_step_s31.jpg: Create an image showing this exact step in an automotive refinishing lesson: Keep each layer of the featheredge at least ~1/2 inch wide so it will not map. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 4 โ€” save as ase_b2a_step_s41.jpg: Create an image showing this exact step in an automotive refinishing lesson: Scuff the surrounding panel, then check by feel and sight; you should not feel a ridge. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 5 โ€” save as ase_b2a_step_s51.jpg: Create an image showing this exact step in an automotive refinishing lesson: Blow off, wipe, and clean before priming. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.

Remember: Level to 150, then featheredge 180 to 220 to 320. Each layer at least 1/2 inch wide, with no ridge you can feel.

๐Ÿ”ง Practice in the Lab: Featheredge a repair

GoalFeatheredge a chip/repair through 180 โ†’ 220 โ†’ 320 so each layer is at least ~1/2 inch wide.
Skill checkA fingernail dragged across feels no step; the layers are visible and gradual.
[VISUAL PLACEHOLDER] Block sanding primer with a guide coat showing lows.

Block sand primer & filler

ASE Surface Prep Task ยท A9"Block sand the area to which primer-surfacer has been applied."What it means: level the cured primer dead flat with a block and a guide coat before sealer and color.
Why it matters: Block sanding cuts the primer-surfacer dead flat and removes sand scratches so the gloss does not reveal waves or rings.
How it's done: Apply a guide coat, block sand with a firm block through progressively finer grits until the guide coat is gone and the surface is flat, without breaking through.
What you need: Sanding blocks, a guide coat, and abrasives in progressively finer grits, plus a respirator and eye protection.
โš  Common Pitfalls
  • Block sanding without a guide coat, so you cannot see lows and highs and you leave waves that show under gloss.
  • Using your fingers or a too-soft pad instead of a real block, which follows the dents instead of cutting them flat.
  • Sanding through the primer-surfacer back to filler or bare metal in spots, then coating over an inconsistent surface.
  • Finishing too coarse for the sealer or topcoat, so sand scratches show.
Key pointsA flat sanding block plus a guide coat finds highs and lows that a hand or DA will miss, and gets the primer truly flat before sealer and color. Block sanding is done over cured primer-surfacer, usually wet, so the surface comes out level with the surrounding paint.
Tools & suppliesFirm flat blocks and long boards (durablocks) for flat panels, flexible or foam blocks for curves, guide coat (dry guide-coat powder or a light dust of a contrasting color), a spray bottle or hose for wet sanding, and P-grade silicon-carbide wet paper. Use the longest block the panel will allow.
Grit & techniqueGuide coat the cured primer, then block 220 wet, then 320 wet. Refinish-level final sanding starts at 400 wet, so finish to the grit the sealer or topcoat calls for (commonly P400 to P600). Cross-block in an X pattern at angles to level the surface, with the final strokes lengthwise (with the panel). The guide coat stays in the lows and disappears on the highs. (Confirm the final grit on the paint maker's data sheet.)
Best practiceEven pressure, let the block find the highs; do not rock it. Wet sand with a spray bottle or hose and clean running water, never a dirty bucket whose sludge will scratch the panel. Leave masking in place to keep sludge out of crevices. A guide coat prevents oversanding and shows missed spots. If you break through to filler or bare metal, re-prime that spot.
How to Do It (Step by Step)
  1. Apply a guide coat over the cured primer-surfacer.
  2. Cross-block 220 wet, then 320 wet, in an X pattern, with clean running water; finish strokes lengthwise.
  3. Read the guide coat: it stays in the lows and disappears on the highs.
  4. Re-prime and re-block if lows or pinholes remain.
  5. Finish-sand to the grit the sealer or topcoat needs (P400 to P600).
๐ŸŽฌ Video demo + narration
Film this procedure (or build a narrated slideshow from the step images). Save as ase_b2a_demo_demo.mp4 in this category's images folder, then swap this box for a <video> player.
Narration script (read in order):
  1. Apply a guide coat over the cured primer-surfacer.
  2. Cross-block 220 wet, then 320 wet, in an X pattern, with clean running water; finish strokes lengthwise.
  3. Read the guide coat: it stays in the lows and disappears on the highs.
  4. Re-prime and re-block if lows or pinholes remain.
  5. Finish-sand to the grit the sealer or topcoat needs (P400 to P600).
๐Ÿ“ท Step-by-step image prompts โ€” consistent series (generate in one session; reuse the same subject/style reference so every step matches)
Step 1 โ€” save as ase_b2a_step_s11.jpg: Create an image showing this exact step in an automotive refinishing lesson: Apply a guide coat over the cured primer-surfacer. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 2 โ€” save as ase_b2a_step_s21.jpg: Create an image showing this exact step in an automotive refinishing lesson: Cross-block 220 wet, then 320 wet, in an X pattern, with clean running water; finish strokes lengthwise. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 3 โ€” save as ase_b2a_step_s31.jpg: Create an image showing this exact step in an automotive refinishing lesson: Read the guide coat: it stays in the lows and disappears on the highs. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 4 โ€” save as ase_b2a_step_s41.jpg: Create an image showing this exact step in an automotive refinishing lesson: Re-prime and re-block if lows or pinholes remain. CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.
Step 5 โ€” save as ase_b2a_step_s51.jpg: Create an image showing this exact step in an automotive refinishing lesson: Finish-sand to the grit the sealer or topcoat needs (P400 to P600). CONSISTENT SERIES STYLE (keep identical across every step): the SAME refinish technician (same face and build, navy shop uniform), the SAME clean, brightly lit collision-repair booth, the SAME medium working camera distance and soft, even lighting. If a technician or hands appear, show correct PPE for the task. Photorealistic, true-to-life color, no text, no watermark. Aspect ratio 16:9.

Remember: Guide coat, then block. Cross-block 220 then 320 wet, finish strokes lengthwise, and let the block tell the truth about flat.

Check what you learned

Remove the finish

Using a chemical aircraft stripper to remove automotive finishes presents all of the following hazards EXCEPT:

Airborne dust. Chemical stripping dissolves the paint, so it does not throw dust like sanding does. The real hazards are burns, fumes, and runoff.

Featheredge

To prevent repair mapping, what is the minimum acceptable width for each individual paint layer in a sanded featheredge?

One half inch. Each layer needs roughly a half inch of taper so the transition is gradual enough not to telegraph through the finish.

# Numbers & Specs for this module

Grit progression (verify on the abrasive and paint data sheets): 36 to 40 grit strips all coatings; 80 shapes filler; 180 removes the 80-grit scratches. Level bodywork to 150 before featheredging. Featheredge 180 โ†’ 220 โ†’ 320. Block sand primer 220 wet โ†’ 320 wet. Final sand before sealer/base: P400 dry (DA), P500 dry (hand), or P600 wet. Never skip grits.

Scuff pads: red/maroon โ‰ˆ 320โ€“400 (aggressive scuff/new parts); gray โ‰ˆ 800โ€“1000 (blend areas, plastic); white/gold โ‰ˆ 1200โ€“1500 (light scuff). Abrasive material: aluminum oxide for general sanding and primer; silicon carbide for wet sanding and paint.

Featheredge width: keep each paint layer at least about 1/2 inch wide so the repair does not map.