Not sure if this belongs here or Problem solving, but here goes.

I bought some thin stainless steel sheet. I want to make it into something to drink out of. I have not been able to find a grade on it anywhere. I asked my steel merchant, he said if it was " line marked"that would tell me, otherwise I was out of luck.

Here is my question: Are there any grades of stainless that are not food safe? Are any toxic? Is there any way to test to narrow down what type it might be?

Any other questions, comments, concerns? Anything I should know?

I believe that line marked would refer to any identifier that might be ink jet printed on the material itself, or any pvc coating on it.
As for being safe, barring any oils or anything else on the surface, you should be fine.
Stainless is divided by the finish. alloy, etc. At the end of the day, it is the final application that determines the grade required. Cosmetic, structural, etc.

Hope this helps!

there are food grade stainless I believe, but I am not sure if the others are not recommended for drinking. But worth checking into.

i used to work for a company that made race car parts and we used 304 stainless for the tail pipes and you could polish it and it would stay that way the rest were 403 stalless and that would oxidize or get this rusty like coating on it i think 304 is food grade now i don't know if there is a way to tell that would be cost afective

304 is whats in a lot of the places I worked on in Ft Wayne, bars & restaurants like hooters... because I put it there.

Stainless takes aprox 30% more energy to work it, and let me tell you, thats a lot!! Before I figured it out, I had a heck of a time wondering why what I was doing was so difficult. Good Luck!

For those who might be interested in the wacky world of Stainless steel, I dug around in my assorted info here at work and below is a list of stainless steel types/grades.

440A
440B
440C
440F
430
409
410
301
301LN
304L
304L
304LN
304
304H
305
312
321
321H
316L
316
316LN
316L
316L
316
316Ti
316LN
317L
904L
What it all boils down to is resistance corrosion, heat treat properties, strength, things of this nature. It just depends on what application the material is being used for. Most of the food service industry uses (if it is not cosmetic) the cheapest stuff available. The high end appliance makers use the uber nice grained materials.
Oh, by the way, when you have a choice between your nicey SS fridge and the painted one beside it, they both have the same guts inside. Trust me,, I wrote the blanking programs for most of the major fridge and stove manufacturers that use stainless.

i no about the fridge thing that there the same in side but try to convince the oldlady of that its not worth the savings let her have it and your alot better off ;)

There is certain percentage of people,allergic to ingredients(nickel) included in some s.steels.A few weeks ago I've got this reaction while putting my bare feet on galvanized bar stool(!).Sweat dissolved minimal amount of it and poor me had sore blisters for over 1 week...You never know,what's gonna itch you 'till is too late.Anyway,if is it ,,common" (understand ,,cheap")sheet metal,used for sinks and other stuff,it SHOULD be OK.

Dairy equipment specs. (In Oregon anyway) call for 18-8 stainless steel for milk tanks, pipelines etc. 18-8 refers to the percentages of chromium and nickle.
Warren

The food grade of SS, usually an Austenitic SS like 304 (this is an 18-8 SS too), is non-magnetic. The Ferrtic grades, generally the 400 series, and Martensitic grades, also 400, are magnetic. After forging it, you will have created chromium carbides that will cause the steel to rust because too much of the protective chromium is tied up as carbides. Heat the piece to about 1850F, or as hot as you can get it, and quench it in water. This will not harden the piece as there is too little carbon and too much nickel to form martensite. The heating dissolves the carbides and the quenching prevents them from re-forming upon slow cooling. If you could determine it was 304L, the carbon would be low enough that you would not need to worry about the carbide formation.

Edited February 18, 200917 yr by Quenchcrack
addition

Thanks, all

I was looking for 18-10 or 18-8, because if its what silver ware is made of it should be fine. I looked for line marking. I picked it up at a steel supplier...Logan steel in CT. It has no line marks... so its mystery SS. And yes I have played with SS before, takes 30 to 50% more work, I also found that the pliable temp is very narrow, not much work time, and over heating lead to breakage or over cystalization.

Also thanks for the advice about dissolving the carbides!