Mr. Waterproof Sand Paper Set Rough MT301: Wet Sanding Guide

Quick answer

Use Mr. Waterproof Sand Paper Set Rough MT301 for wet sanding to remove nub marks and prep plastic before painting. Soak the paper, sand with light pressure, and keep the surface wet. This set's rough grit makes it ideal for initial shaping, but you'll need finer grits for a polished finish.

Why wet sanding beats dry sanding for Gunpla

Wet sanding with waterproof paper like Mr. Waterproof Sand Paper Set Rough MT301 reduces airborne dust and prevents clogging. The water carries away plastic particles, so the abrasive stays sharp longer. It also leaves a smoother scratch pattern, which matters when you apply paint or topcoat. For bare plastic, wet sanding minimizes the whitening that often appears around nub marks. If you plan to paint your kit, wet sanding is the safer choice because it won't leave residue that interferes with adhesion. Keep a bowl of clean water nearby and dip the paper often.

How to choose the right grit for each task

Rough grits (like those in the MT301 set) are for shaping and removing large nub marks. They cut fast but leave visible scratches. For final smoothing before paint, step up to finer grits (800, 1000, 1500). The MT301 set is labeled 'Rough,' so it's best for the initial stage. If you only have this set, you can still get a decent finish by sanding progressively and then using a polishing compound. But for a glass-smooth surface, you'll want additional finer papers. Always sand in one direction per grit to avoid cross-hatch scratches.

Step-by-step: wet sanding with MT301

Follow these steps for best results. Work on a clean, well-lit surface. Cut a small piece of sandpaper—about 2x2 inches—and soak it in water for a few minutes. Hold the part securely. Sand with light, even strokes. Rinse the paper and part frequently to remove debris. Check your progress often; don't over-sand. After rough sanding, switch to finer grits if available. Dry the part thoroughly before painting. For nub marks, sand flush to the surface, then blend the area. A common mistake is pressing too hard, which gouges the plastic. Let the abrasive do the work.

Wet sanding steps with MT301

1. Soak the sandpaper: Cut a small piece of MT301 and place it in clean water for 5–10 minutes until it becomes pliable. Checkpoint: The paper should feel soft and flexible, not stiff.
2. Sand with light pressure: Hold the part firmly and sand the nub mark or seam with gentle, even strokes. Keep the paper and plastic wet by dipping frequently. Common mistake: Pressing too hard can gouge the plastic or create deep scratches.
3. Rinse and inspect: Rinse the part and paper in water to remove debris. Dry the part and check if the nub is flush. Repeat if needed. Checkpoint: The surface should feel smooth, with no raised bump.
4. Progress to finer grits: After rough sanding, switch to finer grits (800–1500) to remove scratches left by the rough paper. If you don't have finer grits, use a polishing compound. Next step: For painting, ensure the surface is clean and dry before applying primer.

Product facts

• Mr. Waterproof Sand Paper Set Rough MT301: Mr. Waterproof Sand Paper Set Rough MT301 is a practical sanding set for model building and finishing tasks, designed for wet sanding to reduce dust and provide a smoother finish. Wet sanding keeps dust down and gives a smoother scratch pattern, which is ideal for preparing plastic before paint.
• Mr. Waterproof Sand Paper Set Rough MT301: The set includes rough grit sandpaper suitable for initial sanding and shaping. Use it for removing nub marks and shaping, but follow with finer grits for a polished surface.