Is 80 grit sandpaper good for metal?

When working with metal, having the right sandpaper grit is important for achieving the desired finish. Sandpaper comes in a range of grit sizes, from coarse grits like 24 or 36, to fine grits like 220 or higher. 80 grit sandpaper falls on the coarser side of the spectrum. But is it a good choice for preparing and finishing metal surfaces? Here is a detailed look at whether 80 grit sandpaper is good for metal.

What is 80 Grit Sandpaper?

Sandpaper grit indicates the number of abrasive particles per inch of sandpaper. The lower the grit number, the coarser and more abrasive the sandpaper will be. Higher grit numbers indicate finer sandpaper. 80 grit sandpaper has relatively large, coarse abrasive particles with 80 particles per inch of sandpaper.

The coarse particles and texture of 80 grit sandpaper make it ideal for tasks like:

• Removing rust, old paint, corrosion from metal surfaces
• Smoothing out rough edges and defects
• Shaping and forming metal pieces
• Removing welds and other heavy material

The open coat design of 80 grit also helps clear out metal debris, dust and swarf when sanding. While good for removing material, 80 grit leaves behind a rough scratched surface. Finer sandpaper is needed after 80 grit to polish and refine the surface.

When to Use 80 Grit Sandpaper on Metal

Here are some of the main scenarios where 80 grit sandpaper works well for metal:

Removing Rust and Corrosion

For removing heavy rust, corrosion, and old paint from metal, 80 grit is often a great starting grit. The coarse abrasives make quick work of cleaning off oxidized layers and deteriorated coatings. 80 grit is abrasive enough to expose fresh clean metal below while not being overly aggressive. Follow up with 120 or 150 grit sandpaper after to smooth out scratches.

Smoothing Rough Edges

For metal pieces with rough burrs, edges or defects, 80 grit quickly takes down high spots and evens out the surface. The open coat design helps clear out the debris. Move up to finer grits after for a smoother finish.

Shaping and Forming

The fast cutting action of 80 grit makes it a good option for shaping and forming metal pieces to size. For tasks like rounding, beveling or deburring metal, 80 grit can remove material efficiently while being easy to control compared to extra coarse grits.

Removing Welds, Rivets, Bolts

When removing welds, rivets, bolts or other heavy stock from metal, 80 grit has the cutting power to grind through thick material. The coarse grit makes fast work of grinding off welds and hardware. Move down to finer sandpaper to finish the surface.

Prepping for Paint, Powder Coating

As a first step to prep metal for painting or powder coating, 80 grit creates an ideal tooth for paint adhesion. It exposes clean metal and etches the surface, so paint bonds tightly. Make sure to smooth with finer grits after.

Benefits of Using 80 Grit Sandpaper on Metal

Here are some key benefits of using 80 grit sandpaper for your metal projects:

Removes Material Quickly

The coarse particles and open coat design of 80 grit allow it to cut through metal rapidly. It saves time and elbow grease removing layers of rust, paint and grime.

Exposes Bare Metal

80 grit abrasives dig down through corrosion and coatings to reveal fresh steel, iron or other metals underneath. This is great for refinishing or repairing metal items.

Creates Tooth for Painting

The deep scratches left by 80 grit give paint and coatings something to grip onto. This leads to greater paint adhesion and more durable finishes.

Affordable and Readily Available

As a common medium grit, 80 sandpaper is easy to find and quite affordable. It provides a good balance of cutting speed and cost-effectiveness.

Compatibility with Power Sanders

The durable construction of 80 grit makes it compatible with power sanders like random orbit sanders that generate high sanding forces. Pressure is evenly distributed.

Disadvantages of 80 Grit for Metal

While suitable for heavy stripping and shaping, 80 grit also has some disadvantages to consider:

Very Aggressive

The coarse particles cut very fast and can damage softer metals if you are not careful. It requires a light touch.

Deep Scratches

80 grit leaves behind very deep scratch patterns that need extensive smoothing with higher grits before finishing. It cannot produce a refined surface on its own.

Not for Finer Work

For detailed metal work, etching, polishing, 80 grit is simply too abrasive. Finer sandpaper in the 120-220 range is better for finishing work.

Prone to Clogging

The deep scratches and open coat can cause 80 grit to clog when sanding softer metals. Frequent cleaning is needed to prevent clogging.

Best Practices When Using 80 Grit Sandpaper on Metal

To get the best results from 80 grit sandpaper on metal, follow these tips:

Use Light Pressure

Let the sandpaper do the work. Excess pressure causes deeper scratches. Use a light touch and simply guide the sander.

Keep it Moving

To prevent gouging, keep the sandpaper moving across the surface. Avoid focusing too long in one spot.

Work Across Multiple Grits

Start with 80 grit to expose bare metal, then work up to 120, 150 and 220 grits for a smooth polished finish.

Clean Frequently

Pause regularly to blow away dust and debris for fresh abrasive action. Clogged sandpaper causes scratches.

Lubricate When Wet Sanding

If wet sanding, apply water or a lubricant to prevent loading. This extends sandpaper life.

Maintain a Flat Sanding Block

To prevent contouring damage on flat surfaces, ensure your sanding block is perfectly flat.

Steps for Effectively Using 80 Grit Sandpaper on Metal

Here is a simple process for properly working through the grits when sanding metal:

1. Start with 80 grit to remove any rust, paint or corrosion. Use light pressure working in the direction of the grain. Clean the sandpaper frequently to prevent clogging.
2. Next, step up to around 120 grit to start smoothing larger scratches. Check for any pits or imperfections.
3. Progress to 150 grit to further refine the surface. Sand until all deep 80 grit scratches are gone.
4. Finally, move up to 220 grit. This will leave a smooth uniform scratch pattern. Go higher for a polished mirror finish.
5. Once satisfied with the smoothness, wipe clean and apply your desired paint, clear coat or other finish.

FAQs About Using 80 Grit Sandpaper on Metal

Is 80 grit too coarse for metal?

80 grit is on the coarse end of the spectrum but serves an important role for heavy removal on metal. The key is following up with finer grits after to smooth out the deep scratches it leaves behind. Used properly as part of a multi-grit process, 80 grit is not generally too coarse for metal work.

What metals can I use 80 grit on?

On hard metals like steel, iron and higher carbon alloys, 80 grit works well for stripping and shaping. Use caution on softer metals like aluminum, brass, pewter etc. Start with a finer 100-120 grit and test on a scrap first to ensure the 80 grit is not too aggressive.

Can I use 80 grit to polish metal?

No, 80 grit sandpaper is too coarse to achieve any sort of polished or brushed metal finish. You will need to work through a series of finer grits in the 120-220+ range followed by a polishing compound to achieve a polished look.

What sanding pattern should I use with 80 grit?

To achieve uniform smoothing, sand in straight overlapping lines moving in the direction of the metal grain. Diagonal, circular patterns create uneven scratches that require more sanding to remove. Use straight motions for efficiency.

How much pressure should I apply with 80 grit sandpaper?

Since it is so coarse, 80 grit cuts very fast with just the weight of your hand. Excess pressure causes deeper scratches. Keep pressure between 3-5 lbs letting the sandpaper do the cutting. Too much force can damage softer metals.

Conclusion

In conclusion, 80 grit sandpaper serves an useful role for shaping, stripping and prepping metal for finishing when used properly. Its fast cutting coarse grit makes quick work of removing rust and corrosion to expose fresh bare metal. However, the deep scratches it leaves behind require additional sanding with 120, 150 and 220 grits to achieve a smooth surface ready for painting or clear coating. As part of a multi-step sanding process, 80 grit can be highly effective at removing material quickly while still allowing finer polishing.