The choice of materials for food applications is critical if we are not to poison someone.
As Masters of Metals- ahem, machinists- many of us feel that there is no need to buy the expensive store bought items that we can easily cobble together from a few common on hand materials.
I’ll pass along the University of Maryland’s word of caution to avoid zinc for food contact and high temperature (fire) applications.
While the temperatures involved in smoking foods are far lower than those encountered in welding and metal flame cuttting, the minimal risk of zinc is unneccessary.
The use of galvanized (zinc containing) steel grates – from old refrigerators or chicken cages or galvanized fencing should be avoided for applications actually touching food.
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So if you are determined to make your own Rube Goldberg food preparation equipment what metal should you use?
National Sanitation Foundation (NSF) recommends stainless steel:
NSF 51 Sect 7.1 Stainless steel
7.1.1 Stainless steel used in food equipment shall be of a type in the AISI 200 series, AISI 300 series, or AISI 400 series.
7.1.2 When used in a food zone, stainless steel shall have a minimum chromium content of 16%.
Stainless steel with a chromium content of less than 16% may be used for cutlery, blades, and similar applications requiring a sharp edge, provided the alloy has been hardened or tempered by an appropriate post-weld heat treatment process.
We don’t know why NSF thinks that the heat treat needed is a post weld heat treatment, (who is welding blades?) The blades may be quench and tempered to develop microstructure and toughness… but we’ll still trust their opinion about the safety aspects.
Now who has a great recipe for a dry rub…