Sodium Hydroxide on Cents

[texasrichard]

What with all the talk I decided to try out a theory. As I have easy access to high alkalinity chemicals here is what I did...

 

I found 22 cents in my desk. Just random change. The oldest was a 1971 and the newest 2007. The were all in varying condition from corroded to bright red.

 

I placed all 22 in a glass jar that held a chemical that we use that is basically caustic soda. It is 31% Sodium Hydroxide. (CAS 1310-73-2)

 

I let the cents sit for 1 hour.

 

I then rinsed them in RO water and let them air dry. No heat was ever applied.

 

I don't know if this little experiment helped me understand anything or not. Of the 22 cents in the jar there was little to no change on 19 of them.

 

3 of the 22 do now exhibit color that was not present before.

 

A 1984-D is pretty much BU (with some dark spots) on the REV, but the front that was mostly RB towards brown before now has pink, blue and purple color.

 

A 2003-P is BU on the OBV but now has some pink / bluish on the REV

 

A 2005-D now shows some bright yellow patches on the OBV while the REV has the same yellow along with some vibrant purple.

 

Of the coins that didn't have any noticable change there were BU's to dark browns.

 

I'd say the MS70 has components other than the alkali that help contribute to the color change. OR another thought is that it isn't the copper changing color, it is something ON the copper changing color.

 

Anyway that's the extent of my testing and the cents will be dropped in a local charity jar.

 

BTW none of the ones that changed color are what you'd consider "attractive".

[MikeInFL]

Pics?

[texasrichard]

I took a before of the group but didn't take an after. I'll try to take one Monday when I get back to work and post them.

[physics-fan3.14]

OR another thought is that it isn't the copper changing color, it is something ON the copper changing color.

 

Indeed, that theory makes sense to me.

[texasrichard]

Here's the pics I'd promised... btw, the sodium hydroxide mixture that I put these cents in is strong enough to eat through your leather tennis shoes in a matter of a couple hours or so. It's very strong.

 

First a before shot...

 

Group "after" shot...

 

A couple with the color...

 

As I said not too different other than a couple that picked up some color.