304 vs 316L Stainless Steel: Why Surgical-Grade Makes All the Difference

If you want to get very technical, research shows the following... (I love to dig deep when I research.)

Type 304 stainless steel, while widely used and generally resistant to corrosion, is not as durable or resilient as 316L surgical-grade stainless steel. 

Here are some things that can negatively affect a 304 stainless steel kitchen sink:

1. Exposure to Chlorides (Salt and Harsh Cleaners):

Chlorides, commonly found in salt, certain foods, and harsh cleaning products like bleach, can cause pitting corrosion in 304 stainless steel. This type of corrosion creates small, deep pits that can compromise the sink's structural integrity.

2. Hard Water Deposits:

In areas with hard water, mineral deposits can build up on the surface of the sink. Over time, these deposits can trap moisture and chemicals, leading to discoloration and corrosion.

3. Acidic Foods and Liquids:

Prolonged exposure to acidic foods like citrus, tomatoes, vinegar, or even coffee can dull the finish and potentially degrade the surface if not cleaned promptly.

4. Scratches and Abrasions:

 The typically used 304 alloy is more prone to visible scratches due to its chromium-only composition, whereas 316L Surgical Grade Stainless Steel offers better scratch resistance thanks to its molybdenum content, which enhances wear resistance and reduces surface abrasion. 

5. High Temperatures and Thermal Cycling:

While 304 stainless steel is heat-resistant, rapid temperature changes (e.g., pouring boiling water into the sink followed by cold water) can cause thermal stress and degrade its structure over time.

6. Chemical Cleaners and Abrasives:

Harsh chemical cleaners (especially those containing chlorine or muriatic acid) can attack the chromium oxide layer that provides corrosion resistance. Abrasive cleaning tools can damage the surface, leading to rust and staining.

7. Iron or Steel Contact:

The typically used 304 alloy is also susceptible to "tea staining" or localized rust. This occurs through galvanic corrosion when 304 comes into contact with other iron or steel objects in a moist environment. In contrast, 316L Surgical Grade Stainless Steel offers added protection against such corrosion, thanks to its molybdenum content. 

8. Improper Maintenance:

Failure to clean and dry the sink regularly can allow water spots, soap scum, and food residues to degrade the surface finish, making it look dull and less resistant to corrosion. This is not the case with 316L alloy!

8. Standing Water:

Water left sitting in the sink, especially with dissolved minerals or cleaning agents, can create an environment conducive to corrosion and staining.

9. Food Residues:

Foods like mustard, pickles, or sauces with high sulfur or chloride content can cause discoloration or pitting if left on the sink for extended periods.

10. Environmental Factors:

High-humidity environments or exposure to salty air (e.g., near coastal areas) can accelerate the corrosion process in Type 304 stainless steel.

11. Low-Quality or Untreated Water:

Water with high levels of iron, sulfur, or other contaminants can react with the sink surface, causing staining or corrosion.

Advantages of 316L Over 304:

316L contains molybdenum, which significantly enhances its resistance to chlorides, acidic conditions, and pitting corrosion. It also has superior strength and durability, making it ideal for high-use environments like kitchens. 316L stainless steel is also more scratch resistant than type 304 stainless steel. These advantages allow manufacturers like Rachiele to confidently offer a lifetime transferable warranty on sinks made with 316L stainless steel.