Polishing for Food Grade Stainless Steel

Stainless steel components for the food processing industry must be strong, durable, non-reactive, and smooth. These qualities enable the material to stand up to the rigors of food handling, processing, and preparation. In particular, smooth finishes on stainless steel are vital to maintaining safe and sanitary conditions by preventing the buildup of debris and bacteria on the surface. Experienced suppliers with specialized knowledge are best equipped to polish stainless steel to meet these critical hygiene and performance requirements.

Learn more about the stainless steel polishing process, types of finishes, types of polishing, and more.

Stainless Steel Polishing

Polishing stainless steel is an important finishing step that can improve both aesthetic and functional qualities of many products and components. Benefits include:

• Achieving a desired aesthetic, from rough and dull to mirror-like shiny finishes
• Minimizing irregular surfaces that can harbor dirt, debris, bacteria, and other contaminants
• Reducing the likelihood of damage from oxidation and corrosion
• Improving the performance and service life of polished parts

The Stainless Steel Polishing Process

The traditional process of polishing stainless steel involves treating the material with increasingly finer abrasive materials, which include ceramics, zirconia, and alumina. Over the course of three to seven steps, stainless steel surfaces are scoured with these grinding materials until the desired surface finish is achieved. Using grit strengths ranging from 50 to 3,000, operators can create standard finishes ranging on a scale of 0-10.

Finishes with the lowest numbers (#0-2) are considered “mill finishes,” indicating their minimal treatment after production. These mill finishes use treatments such as annealing (slow cooling), pickling, and passivation (acid baths) for protection and mildly increased smoothness. A #3 finish provides a slightly smoother finish, but it features rough, uniform parallel lines.

Finishes #4 and higher represent surfaces that are more satiny or shiny. Finishes higher than #6 offer varying degrees of sheen, from the reflective #7 to the glassy, mirror shine of #9 and #10.

Types of Finishes for Food-Grade Stainless Steel

Finishes #4 to #6 are the most commonly used finishes for applications requiring food-grade materials. #4 is often called “dairy finish” for its common use in dairy and other commercial processing equipment. #5 satin and #6 satin Scotch-Brite™ finishes have a higher reflectivity and polish and are used for such products as appliances, countertops, food-processing equipment, cabinets, cases, protective panels, and other food-grade environments. These applications benefit from the smooth, clean look of these finishes that minimizes the appearance of fingerprints and oils while also minimizing the risk of cross-contamination.

AAA Metals specializes in creating #4, #5, and #6 finishes for our customers’ food-grade stainless steel needs.

Abrasive Polishing for Food-Grade Stainless Steel

Hygiene standards require that food-grade stainless steel features a degree of smoothness (typically finishes #4-#6) that prevents dirt, debris, bacteria, and other microorganisms from lurking in grooves, pits, scratches, and other recessed areas. Stainless steel can meet these standards when buffed or rubbed with these abrasive polishing materials:

• Sandpaper
• Polishing compounds
• Grinding wheels

Common abrasives include alumina, zirconia, and ceramic materials, applied in progressively finer granularity. Proper polishing of food-grade stainless steel makes the surfaces easy to clean while ensuring no contaminants are introduced during polishing.

Electropolishing for Food Grade Stainless Steel

Electropolishing is another way to polish stainless steel for use in food-grade applications. The process involves immersion in an electrolyte bath charged with DC power, which improves the cleanliness, corrosion resistance, and surface finish of the stainless steel component. These smooth surfaces are highly resistant to accumulating debris and bacteria, and they are easily cleaned and sterilized to meet any food-grade application.

Benefits & Applications

Busy food handling and processing environments require equipment and utensils that meet stringent food industry requirements for performance and cleanliness. Food-grade stainless steel can be used in products as diverse as food processing equipment, knife blades, worktops, cookware, appliances, spatulas, and more. With easy maintenance and cleaning requirements, stainless steel is an ideal material for long-lasting performance and hygienic conditions.

Polishing for Food-Grade Stainless Steel Services From AAA Metals

At AAA Metals, our decades of experience with specialized metal supply and distribution include extensive knowledge and equipment for polishing stainless steel to meet diverse industry needs, including food-grade polishes on stainless steel. Request a quote to get started on your next stainless steel polishing project.