600 vs 800 Grit Sandpaper: Choose by Scratch Depth, Not Shine

Start with the scratch you must remove

600 and 800 grit are both fine refinement steps, but they do different amounts of work. Within the same grading system and abrasive family, 600 removes a 400- or 500-grit pattern faster and leaves a more visible replacement scratch. 800 cuts more slowly and leaves a finer pattern for a later coating, compound, or polishing step. The correct choice is set by the existing scratch and the next process—not by how glossy the wet surface appears.

Water can temporarily fill scratches and make a panel look clearer. Slurry can hide deeper lines. A surface that shines while wet may still reveal an incomplete pattern after it is rinsed and dried. Build the decision around dry inspection checkpoints.

Place the job on a scratch-depth ladder

First identify the material and the layer being sanded. A cured primer, a clear coating, solid plastic, resin, and bare metal do not share one universal sequence. Confirm that abrasion is permitted and that enough material remains to remove the defect without exposing an edge, color layer, fiber, or substrate.

Then classify the condition:

1. A deeper, clearly visible previous-grade pattern: 600 is usually the more efficient candidate, provided the process specification allows it.
2. An even 600 pattern that needs refinement: 800 is a logical test step.
3. A faint isolated defect in a thin coating: neither grade should be automatic; measure the risk of breakthrough and start with the least aggressive approved method.
4. Unknown haze or contamination: clean and identify it first. Abrasion cannot diagnose residue after it has already removed material.

The purpose of 800 is not to make an unfinished 600 step disappear by extra pressure. Complete the 600 pattern at light, controlled pressure, then let 800 replace it.

Use a three-checkpoint test

Choose a small flat area away from edges and mask a reference strip. Fit fresh abrasive to a suitable support. Keep the support, lubricant, pressure, and stroke pattern consistent so the grade is the main variable.

Checkpoint one: after a few passes. Rinse or remove dust, dry the area fully, and inspect with a stable point light. If 800 is barely changing the deeper scratch while 600 removes it predictably, begin with 600. If the surface already carries a shallow uniform pattern, 800 may avoid unnecessary material removal.

Checkpoint two: before changing grades. The original defect or previous-grade scratch should be gone across the intended area. Random deeper lines mean contamination, uneven support, or an incomplete step. Correct the cause before advancing.

Checkpoint three: after 800. Dry the area again. Confirm that the 600 pattern has been replaced with a consistent finer pattern and that edges, body lines, and surface shape remain intact. Only then evaluate the specified next step.

A pencil witness mark can help on a rigid, opaque test surface when the material maker permits it, but do not use a marker whose dye or solvent can contaminate a coating. Light and a clean dry surface are the more universal checks.

Do not confuse refinement with final gloss

Abrasive grade describes the scratch-producing step, not the completed appearance. Many high-gloss systems require additional finer grades, compounding, or polishing. Some coating-preparation systems intentionally stop with a uniform matte scratch so the next layer can bond. In either case, chasing shine at 800 can tempt you to dwell, press harder, or thin a sensitive edge.

Manufacturer process guides commonly separate 600-grade primer refinement from 800-grade blend preparation. That is an application example, not permission to transfer an automotive sequence to glass, furniture finish, gelcoat, or plastic. The product and coating instructions remain the controlling specification.

Choose concrete sheets after the process is set

For compatible hand-sanding work, eQualle 600-grit sheets in a 10-sheet pack provide the stronger of these two refinement steps. The 800-grit 10-sheet pack provides the finer option, and readers can also choose the same 800-grit sheets when that checkout is more convenient. These are waterproof sheet-format options; that does not make wet sanding safe for every assembly or coating.

Use the 600-grit collection or 800-grit collection to compare pack quantities only after confirming the grade. The 800-grit wet-sanding uses and checks cover that grade in more detail. If the surface is ready for another fine step, the 800-versus-1000 refinement decision explains what should change before advancing.

A short 600–800 selection tip

Let the dry checkpoint make the call

Use 600 when an approved process still needs its greater cut. Use 800 when the deeper work is complete and the next step needs a finer, even pattern. If the layer is too thin or the defect too deep, stop rather than forcing either grade to solve a repair that needs recoating, filling, replacement, or specialist assessment.