What makes natural bone turn dark?

[Buck_Fan]

Hi ya'll,
I have a number of natural bone knives and I love them. Every one has been slowly, some not so slowly, darkening. Like it has little black dots on them. I actually like the contrast. But I wonder what causes this? Is it just aging? One of them is turing a nice brown as well. Some that I have hardly used are doing it as fast as ones I caryy more often. Any thoughts? At first I thought dirt, but it does not look like dirt.

Thanks,

Bill

 

[Absintheur]

Bone is porous and absorbs oils from your skin, this will slowly darken bone as will the dirt the oil attracts. The dirt can be cleaned with a damp soft cloth and this will leave the oils from your skin. Dye does fill up some of these pores and the darker the dye normally the slower the bone will absorb oils because the dye molecules in darker dye are actually tend to take up more room.

 

[pholder]

oil,body acid,oxidation from the elements, that's my guess

 

[Will Power]

Also the level of moisture.I live in a cold dry climate and indoors is very hot&dry, this is NOT having a good effect on some of my knife scales.

Oils will darken bone and the reaction with brass liners can also cause a darkening or greening process.Even leaving knives in the dark-cupboard etc-seems to darken some of 'em.