A recently news about the leak of manganese from stainless steel cookware during heating will damage health catch my eyes. Some manufacture cut cost by using 200 series instead of 300 series which increase the potential.
I warns me to check what we use everyday.
After checking our cookware, I found some of them are already corrosion. One even has a small hole that I may see through the light from the other side. Then I decide to replace them.
SAE Steel Grade
I start studying stainless steel material
Here are my summarize:
200 Series (austenitic chromium-nickel-manganese alloys) – Weaker corrosion resistance compared to 300 series due to decreasing nickel and increasing manganese
300 Series (austenitic chromium-nickel-manganese alloys) – 304, aka 18/8, used in many cookware. It means 18% chromium and 8% nickel. I just bought the IKEA Favorit series and it is labeled as 18% of chromium (18/0).
400 Series (martensitic) – not as corrosion-resistant as austenitic but are extremely strong and tough. It contains chromium (12–14%), molybdenum (0.2–1%), nickel (less than 2%), and carbon (about 0.1–1%).
NSF International Standard
Stainless steel used in food equipment shall be of a type in the AISI 200 series, AISI 300 series, or AISI 400 series. (From 7.1.1 on Page 3)
When used in a food zone, stainless steel have a minimum chromium content of 16%. (From 7.1.2 on Page 4)
For above studying, I decide to go for the 300 series for better corrosion resistance.
Happy ending? No, the Glass Lid is Singing…
The story doesn’t end up here. The glass lid of Tefal keep on making noise during heating. Following video shall help you to understand what happen. You may hear the ticking sound at 00:08, 01:01, and 02:07.
I am not comfortable for the sound and worry about the glass might exposure while cooking. Two different post confirmed my worry. One is from Mobile01 and another is from Amazon. Therefore, I returned the Tefal series.
It’s easy to cook, difficult to prepare and clean up.
Because we used to see rainbow effect in our stainless steel cookware, I study and found a solution.
You may search for many articles about how it works. Here is a video clips to proof it really works.
Similar product in Taiwan called 天工去污粉 which contains lapping compound.
British Stainless Steel Association provides a very detail explain on corrosion in stainless steel. Worth reading.
- Tefal So Tasty
- IKEA Favorit
- Wiki: Stainless Steel
- Stainless Steel: All About Food Grade 304, 18/8 and 18/10
- Food Equipment Materials by American National Standard/ NSF International Standard
- Amazon: Tefal Actifry poor construction, broken paddle, broken lid.
- Mobile01: 我家的特福法國製買不到一年, 上個月也是在我老婆煮飯時暴裂…
- custhelp.com: I’ve noticed a rainbow-like discoloration on my stainless steel cookware. How can I remove it?
- Bar Keepers Friend
- BSSA: What forms of corrosion can occur in stainless steels?