I have been working on a customers deer skull for several weeks now. The skull for the most part is free of grease and whitens up well. I have degreased and whitened several times using dawn/ammonia/ hot water and 20 and 40 volume whitener. This skull has a spot that refuses to degrease on the back of the skull much like a picture that was posted a week or so back. The skull seems to be getting more and more fragile esp. around the nose. Have you ever just told the customer this is as good as I can get it? I have never had this happen.