I have a 2001 SAC$1 proof, and the matte texture extends out in front of her face into the field a short way, and then has a feathered edge (in other words, it fades into the mirrored field, rather than ending abruptly) The only way I can think of this happening is if it was a slightly lower area on the die and didn't get polished. If this is true, it might be worth something as a die variety. Does anyone know what might be the cause of this?
I think you have the right idea, just a bit backwards. Based on your description it sounds like it might be a die polish mark that extended beyond the line of the face and into the field. As kiyardo suggested, post a pic if you can.
Ok, here's the picture: http://flyingmoose.com/sac.jpg The matte area in the field has the same finish as the devices. I was under the impression that the whole die is given the matte finish (sandblasted?), and then the surface polished by holding it up against a polishing wheel or something. In this case, this could be an area that was slightly recessed. If this isn't how they make proof dies, I'd be interested to know.
I would guess that the die got some grease on it and that that is what caused the roughness in the fields instead of the normal polished finish. As to how they make Proof dies, when a die starts out it is a flat piece of metal. It is then polished. Then the die is hubbed and the design pressed into the surface. They used to use sandblasting, but these days I believe they use lasers which are controled by computer to create the rough finish on the devices that provides us with the frosted cameo effect. The the fields of the die are chrome plated to make them even smoother and even more highly polished. The chrome plating also makes them last longer. The die polishing I was talking about takes place after the dies have been used for a while and need touched up. They use small dremel like tools on the devices to polish out imperfections caused by wear. Based on your previous description I thought you were saying that the edge of the face extended further into the fields than it was supposed to which is why I thought it may have been caused by die polishing. In other words, a bit too much metal removed along the edge of the face. But this is not what your picture shows, and now that I have seen it I understand what you were trying to describe. And if the die got some grease on it in the field area and then struck a coin - that's exactly the effect it would produce.
