Monday, June 10, 2013
BONELUST Q&A: "How will I know if a skull needs degreasing, I'm not sure what it even looks like?"
These are my two Mountain Lion skulls. The natural body oils are very apparent on the specimen on the left. The golden coloration is a dead give away that it was never properly processed. Some factors to keep in mind though: yellow can also mean that it was once boiled or chlorine bleach was used in the processing. So avoid both of those things! You can not undo bone that was yellowed by chlorine bleach. It may appear white at first but over time it will yellow. A full rolling boil will draw grease deeper into the bone rather than making it rise to the surface. Once done it is very hard to degrease. Last factor to consider is that the skull on the left was sold to me as "antique". I will be attempting to properly processing this skull in the near future. Only then will I know the true answers to the history of this skull. The skull on the right is still mildly greasy to the eye & touch but not so bad that I feel the need to degrease. Degreasing is a step in bone processing that is purely for preference to the bone collector. I honestly rarely need to degrease anything because it gets mostly taken care of during maceration. With experience you will be able to tell by touch, color and weight if you need to degrease.
For long term preservation, too much oil in bone is bad because bacteria can turn grease into acid and thus damage the bone. But at the same time, 100% grease free makes bone more fragile because grease is a part its natural components and sometimes bones can even shrink a little. A little grease left in bone is best for the longest preservation. I was told by a university teacher that some museums stopped to degrease fully and whiten specimens devoted to research. Now they only do the total bone degreasing for displayed specimens that will not be handled at all. So keep this in mind when deciding on whether you want to degrease or not. I have absolutely noticed a difference in quality of the bones I will or won't use in my jewelry. If they have been fully degreased they just don't seem to be up for being a wearable piece of art that could take daily wear. They also have very little weight which is not good for say a pendant for example.
More related extensive info here:
Whitening Bone Using Hydrogen Peroxide NOT Chlorine BleachBad Words: BOIL & BLEACH
The Mathematics Of Maceration - A HowTo Guide For The Impatient
A HowTo Guide For My Crock Pot Methods