I don't know, I have a 30 year old Kenmore that has yellowed to the point of looking dirty and dingy and it has never been in front of a window. Until recently, I never took it out of the case unless I needed to work on a project and that would be on the dining room table. And when I was finished it went right back in the case and in the closet. The case looks worse that the machine, much more yellow. I never, before now, had a sewing area so I didn't leave my machine set up unless I was working on a particular project such a Halloween Costume or something like that.