View Single Post
Old 17 November 2008, 03:36 PM   #16
sbakar
"TRF" Member
 
Join Date: Mar 2008
Location: North Vancouver
Posts: 650
Quote:
Originally Posted by CanuckRolex View Post
Guys, stop with the toothbrush scratching gold or any metal nonsense.

The plastic fibers in the toothbrush are softer on the moh's scale of hardness than any metal and you cannot scratch something with an item that is softer than the metal being rubbed.

Saying it scratches even when you are using it while it is wet with a mild detergent which will act as an additional lubricant is BS.

Sorry, but I had to call you out on this one, its nonsense.
I'm afraid you may be wrong on this. The Mohs scale is relative...so, yes, the toothbrush bristles will be affected more by the metal than the metal will be by the bristles. HOWEVER...your eye can resolve fine scratches that are mere microns deep on a highly polished surface. Using the tootbrush may well cause fine scratches, especially on softer materials such as gold. It doesn't take much to cause multiple micron-level scratches that are visible to the naked eye.

Here's another example: should ordinary glass be able to scratch sapphire? On the Mohs scale, glass is around 5.5 while sapphire is around 9. By your example, sapphire should not be scratched. However, using a glass point WILL scratch sapphire, as a local Omega dealer will attest after challenging me to rub the crystal on the edge of his glass case. Using only light pressure, I made a slight scratch in his Seamaster's sapphire. Not huge, but it was noticeable. Very high point stress concentrations can be created by pressing through a glass point. This WILL scratch sapphire! Granted, the glass probably came out much worse in this, but the point is that the sapphire DID scratch.

Something else to think about: if diamond is the hardest substance known to humankind, how are we able to cut diamond? By using diamond, of course! Both pieces of diamond have hardness of 10 Moh and will thus wear each other equally. Again, the point is that the Mohs scale is relative. It cannot be said that something will NEVER scratch something else...only how MUCH will it scratch!

Back to cleaning gold: use a mild soap (NO DETERGENT!!! This causes seals to shrink - why risk that??) and warm water and you will preserve the high polish!

SNB
sbakar is offline   Reply With Quote