>dave hillstrom wrote:

>> On Mon, 05 May 2008 02:28:37 -0400, mixed nuts
>> wrote:
>>

>>>dave hillstrom wrote:
>>>

>>>>On Sun, 04 May 2008 19:53:18 -0400, mixed nuts
>>>> wrote:
>>>>

>>>>>dave hillstrom wrote:
>>>>>

>>>>>>ok, so i just scored a 4x8 sheet of thinish, maybe 20-24 gauge metel.
>>>>>>but i cant tell visually if its stainless or chromed. do any of you
>>>>>>know how i could test for this with only a set of files, a torch, a
>>>>>>digital caliper, a 1/100th oz scale, and kitchen supplies?

>>>>>
>>>>>If it's strongly magnetic it would be a steel. Rusts easily.unless
>>>>>galvanized (pretty obvious, that) or cadmium plated (poison). Cadmium
>>>>>is usually chromated (yellow) so that would be obvious as well.
>>>>>
>>>>>Steel is seldom plated before processing - bending or machining cracks
>>>>>the plating making it pointless. Tin plating is bright and sometimes
>>>>>used - but the market for milk cans has evaporated (which is about all
>>>>>it was ever used for).
>>>>>
>>>>>Stainless steels, except for the 400 series, are weakly or non-magnetic.
>>>>>400 series steels (430, 440) contain carbon which makes it harden after
>>>>>heat treating. Will rust but not much. Heat to a blue-oxide color. If
>>>>>it's harder than your file, it could be 440A, B, C, or the ilk (used
>>>>>for scalpel and razor blades - aka surgical stainless steel).
>>>>>
>>>>>Stainless steel of the 300 series work hardens like all gettout - try
>>>>>drilling or hacksawing it 'gently' - if the drill or saw cuts even with
>>>>>light pressure and continues to do so, it's prolly not stainless.
>>>>>
>>>>>High carbon steels spark while being ground. Steels with high carbon
>>>>>1020..1050 don't weld nicely - they get brittle and crack. 1200 series
>>>>>steels contain sulphur and lead (12L14) which make them easy to machine
>>>>>but they're weak and corrode badly - not common in sheet form.
>>>>>
>>>>>It's possible (though not likely if it's not light and fluffy) that
>>>>>it's a 2000 (2024) series or 5000 series aluminum in a hard temper
>>>>>(1100 is soft and won't harden). Most other aluminum alloys (6061)
>>>>>aren't readily acailable in sheet form. Aluminum will react vigorously
>>>>>with lye (or hot sodium carbonate - washing soda) and melts before red
>>>>>heat. Aluminum will also clog your file after a few strokes.

>>>>
>>>>i further believe it to have at once been the exterior panel on the
>>>>backdoor of a semi trailor. does that nail it down? its not ~easily~
>>>>bent, but it can be.

>>>
>>>Truck butt metal. 2024 aluminum (airplane skin - may be 2024 clad with
>>>1100 aka 2219) or 302, 304 or 316 stainless. If it drills easy and
>>>melts before turning red it's aluminum. If it laughs at your drill
>>>and melts only near white hot, it's stainless.

>>
>> it looks kinda chromy, though. not that id mind stainless really.
>> and the holes in it HAVE rusted so its some sort of steel in there.
>>

>Maybe the steel fittings rusted and left a stain? Magnet, mang, magnet.