What do you use to sand stainless steel?

When working with stainless steel, whether for construction, manufacturing, or home improvement projects, it is often necessary to sand the material to achieve a smooth, uniform finish. However, sanding stainless steel can be challenging because it is a hard, durable metal that is resistant to abrasion. Using the wrong sandpaper or technique can lead to frustration and poor results.

Why Sand Stainless Steel?

There are a few main reasons you may need to sand stainless steel:

• Remove scratches and imperfections – Sanding can level out surface scratches or dents for a uniform appearance.
• Prepare for painting/coating – Abrading the surface allows paint or another coating to properly adhere.
• Improve grip – Sanding can increase the surface area to allow glues, tapes, etc. to stick better.
• Deburr edges – Sanding softens sharp edges and burrs after cutting or drilling.

Proper sanding also enhances the overall aesthetic of stainless steel surfaces by blending brush marks and creating a consistent sheen when polishing. It is an essential step in finishing stainless steel to a high standard.

Challenges of Sanding Stainless Steel

Stainless steel is difficult to sand for a few reasons:

• Hardness – Stainless steels have high hardness and tensile strength that resists abrasion from sandpaper.
• Galling – The metals tend to smear or “gall” when sanded, especially at high speeds/friction.
• Work-hardening – Friction work-hardens the surface, increasing wear resistance even further.

These factors make it difficult for the abrasives to “bite” into and cut the stainless steel. Sanding too aggressively can cause surface damage or an undesirable finish.

Choosing the Right Sandpaper

The key to effectively sanding stainless steel is using the proper sandpaper. Here are important factors to consider:

• Grit – Appropriate grit levels are 80, 120, or 150 grit for aggressive stock removal, 320 or 400 grit for general purpose smoothing, and 600 grit or higher for light finishing and polishing.
• Backing material – Paper or cloth backing is preferred over vinyl which can clog easily.
• Bond – The bond refers to the adhesive holding the abrasive grains to the backing. Stronger bonds like zinc stearate are ideal for stainless steel’s hardness.
• Grain material – Aluminum oxide or silicon carbide grains are very hard and sharp for grinding metals.

Sandpapers made specifically for metals are best, often marketed as “stainless steel sandpaper” or similar. These are made of durable materials engineered to resist clogging while abrading hard metals.

Recommended Sandpaper Types

Here are some good sandpaper options for stainless steel:

• Aluminum oxide
• Silicon carbide
• Zirconia alumina
• Ceramic grit
• 3M Stainless Steel Sandpaper
• Norton Beartex Nicromo Sandpaper
• Gator Finishing Sandpaper
• Imperial Wetordry Sandpaper

Using the right sandpaper is critical, but technique is also important when sanding stainless steel. Let’s look at some tips for best practices.

Sanding Technique

Follow these guidelines when sanding stainless steel:

• Always sand in the direction of the grain – Back and forth motions across the grain can create deeper scratches.
• Use light pressure and high sanding speeds – Aggressive pressure causes galling. Use a light touch and high RPMs (electronic sanders) for best results.
• Lubricate the surface – Oil, soapy water, or a specialty lubricant reduces friction, prevents clogging, and gives a smoother finish.
• Work through the grits – Start with a coarse 80-150 grit to remove material, then gradually step up to 320, 400, 600 grits for finishing.
• Keep the sandpaper moving – Prevent clogging and surface damage by using constant, even sanding motions.
• Check frequently for scratches – Scratches will be deeper with coarser grits, so check often to judge when to move up in grit size.

Proper sanding technique maximizes cutting efficiency while minimizing surface damage and scratches. Take the time to thoroughly sand stainless steel through progressive grit sizes for best results.

Power Sanding Options

Manual hand-sanding can work, but using power tools speeds up the process considerably. Here are some of the best power sanders to use:

Orbital & Random Orbital Sanders

Orbital and random orbital sanders feature circular sanding pads that rotate and oscillate for fast, even sanding. The random orbital motion helps prevent swirl marks in the metal. Use with at least 120 grit paper. Options include:

• Makita BO5041 3″ Random Orbital Sander
• DeWalt DWE6421 Random Orbit Sander
• Bosch ROS20VSC Random Orbital Sander
• Ridgid 6″ ROS Sander

Belt Sanders

Belt sanders use a continuous loop abrasive belt to rapidly remove material. Best for fast removal on large surfaces when used with 40-80 grit paper. Good models include:

• Makita 9403 4″ x 24″ Belt Sander
• Wen 6502 4″ x 36″ Belt Sander
• PORTER-CABLE 352VS Variable-Speed Belt Sander

Angle Grinders

Angle grinders with sanding discs are great for finishing hard-to-reach areas and deburring metal edges. Use the lightest pressure possible to avoid surface damage. Top choices include:

• DEWALT 20V MAX Angle Grinder Tool
• Makita XAG04Z 18V LXT Angle Grinder
• Milwaukee 2780-20 M18 Fuel 4-1/2″/5″ Grinder

Each power sander has advantages for sanding stainless steel. Choose the right model for your specific application needs.

Sanding Stainless Steel vs Other Metals

Sanding stainless steel requires different techniques and abrasives than sanding materials like mild steel, aluminum, or brass. Here’s how it compares:

Stainless Steel

• Very hard, requires coarse grit sandpaper
• Use light pressure to avoid work-hardening surface
• Lubrication needed to prevent galling
• Metal-specific sandpapers work best

Mild Steel

• Relatively soft, sandpapers as low as 80 grit can be used
• Wheel clogging not a major issue
• Standard aluminum oxide or silicon carbide abrasives suitable
• Light lubrication optional but not critical

Aluminum

• Soft metal, easily sanded with 120-220 grit
• Prone to surface gouging if too much pressure applied
• Lubricant needed to prevent loading up abrasive
• Does not easily work-harden during sanding

Brass

• Relatively soft, 140-220 grit works for general sanding
• Lubrication needed to prevent loading abrasive
• Work-hardening not a major issue
• Standard sandpapers with aluminum oxide grains suitable

Understanding these key differences allows you to tailor your sanding approach specifically for stainless steel.

Sanding Stainless Steel vs Other Finishes

In addition to uncoated stainless steel, you may need to sand finishes like brushed, polished, or passivated stainless. Here are some tips:

Brushed

• Follow direction of grain pattern
• Can start with 180-220 grit paper
• Finish with 400-600 grit to restore uniform brush lines

Polished

• Start with 320-400 grit to remove scratches
• Work up to 600-800 grit paper
• Finish by re-polishing with buffing wheel/compound

Passivated

• Chemical finish improves corrosion resistance
• Very thin layer, avoid sanding through
• Use 320 grit or higher sandpaper
• Lubricate and use light pressure

Understand how abrasives will interact with any existing finishes on stainless steel to get the desired results.

Sanding Stainless Steel Surfaces

In addition to different finishes, you may need to sand various stainless steel surface types and geometries. Some key factors:

Flat Surfaces

• Easiest surface to sand evenly
• Use “x-pattern” strokes or linear strokes
• Orbital sanders work well

Curved Surfaces

• Follow the curve contour when sanding
• Use smaller diameter sanding discs/pads
• Orbital and angle sanders helpful for contoured areas

Corners and Edges

• Fold sandpaper over to conform to shape
• Use detail sander or angled grinder to access corners
• Sand evenly to avoid rounding over edges

Interior Surfaces

• Use sanding extensions and flexible pads to reach into cavities
• Rotate surface frequently to sand evenly
• Fold sandpaper to fit tight spaces

Adapting your sanding technique for different geometries helps achieve a consistent finish across all stainless surfaces.

Best Practices for Sanding Stainless Steel

Here is a quick summary of tips for effectively sanding stainless steel:

• Select sandpaper made for metals – Aluminum oxide or silicon carbide abrasives.
• Use proper grit – Start with 80-150 grit and work up to 320-600 grit as needed.
• Always sand along grain direction – Avoid circular scratches by sanding linearly.
• Lubricate the surface – Soapy water or light oil helps lubricate and prevent galling.
• Apply light pressure – A light touch prevents damage; let the abrasive do the work.
• Keep sandpaper moving – Reduce loading/clogging with constant motion over the surface.
• Power sand for efficiency – Use orbital, belt or angle sanders for best results.
• Check finish frequently – Step up grits once previous scratches are gone.

Following these best practices will help you successfully sand stainless steel with excellent results.

Safety Tips

Observe basic safety precautions when sanding stainless steel:

• Wear eye protection – Safety glasses help prevent eye injuries from flying debris.
• Use dust extraction – Contain harmful dust particles with vacuum attachments.
• Wear a mask – Use an N95 mask to avoid inhaling fine metal dust.
• Don proper gloves – Gloves improve grip and protect hands from abrasions.
• Unplug tools before changing paper – Electrically safe work habits prevent shocks.
• Keep flammables away – Sparks can ignite flammable liquids/vapors.

Working safely is just as important as working efficiently. Protect yourself and follow all recommended safety practices for metal sanding.

FAQs

Can I use a wire wheel to sand stainless steel?

Wire wheels are not recommended for stainless steel. They remove material very aggressively and often leave deep scratch marks. Sanding discs and sandpaper are better options.

How do I get a brushed finish on stainless steel?

Use 180-220 grit sandpaper and sand linearly along the grain. Firm pressure helps create deeper brushing lines. Finish with 400-600 grit to blend and soften the pattern.

What grit sandpaper should be used on stainless steel?

Start with 80-150 grit to aggressively remove material, 320-400 grit for general smoothing, and 600+ grit for final polishing and finishing.

Can I wet sand stainless steel?

Yes, water can be used as lubrication when wet sanding stainless. This prevents loading up the paper and helps create a smoother finish.

Should I sand stainless steel before welding?

Sanding stainless steel before welding helps create a better welding surface for maximum penetration and bonding of the weld metal.

Conclusion

Sanding stainless steel can seem daunting, but using the proper abrasives and techniques makes the job much easier. The key is having the right sandpaper – durable and hard enough to abrade the surface. Combined with proper grit selection, sanding direction, pressure, and lubrication, you can achieve professional looking results. With some finesse and patience, stainless steel can be sanded and finished to a brilliant uniform surface.