nickel vs. iron

[whitesid]

i got some metal that i think it is nickel. it is magnetic. i was wondering how you can tell the difference between the nickel and a iron or low grade stainless. what do you guys use to tell if something is nickel or iron?
i posted pics so you guys can see what it looks like.

 

[lazersteve]

Nickel is easy to test for:

1. Wet a cotton swab with 1 drop of 32% muriatic acid.
2. Rub the HCl swab on the suspected nickel surface for several minutes.
3. Drip 5 drops of 3% household unscented ammonium hydroxide on the swab where the HCl is.
4. Drip one drop of 1% DMG solution on the swab.
5. Nickel will change the swab pink/red if present.

Steve

 

[peter i]

A nice and easy test (no need to use the HCl, just rubbing with ammonia on the swab will give the same results).


But what gives a brown reaction with DMG?

I was testing some old jewellery before giving my daughter it for playing. Quite a bit of it was positive for nickel (she did not get those), and some of it gave a brown reaction.

I did in in a spot-plate, and the ammonia first turned blue on contact with the metal (expected from a copper alloy), then brown when adding DMG.

When there is only traces of nickel, the complex may take a little to agglomerate, but there was no agglomeration at all, just light brown liquid.

Any ideas?

 

[Chuck_Revised]

Peter...
Are you using the same "3% household unscented ammonium hydroxide" that Steve refers to above? Please specify. A non-acid test for nickel, aluminum, and stainless would be very handy.

Thanks!

 

[peter i]

No, I’m using a concentrated solution called "Triple ammonia" it is a 25% W/W solution of ammonia in water. (Sold for domestic use, since there is no reason to pay for water, when it's so much cheaper to tap it and dilute it yourself).

A commercial test for domestic use is just two small bottles of respectively 1% DMG in ethanol and 5M ammonia solution.

If this method is positive, it only shows that the object is able to give of nickel in an amount that may cause problems with allergy.

300 series steel contains lots of nickel, but will test negative when subjected to this test.
If you want to test steel, I think you will have to apply a drop of AR to it, maybe heat a little, then make it alkaline with ammonia and add the DMG.