Need help with framing?

I want to frame a batik which is about 12" by 15" and I want to mount it on a textured Matt board like black velvety look or just dark paper. I don't think double stick tape would work since humidly would cause it to warp. I want to put another Matt around it and a simple frame. I'm thinking something like wallpaper paste but I don't want it to get moldy. I know there is sticky board for needle work but I would like it to be removable. It's nice but not real valuable but it could be in the future. I am making the frame myself. I want the frayed silk to show in a shallow window box look. It looks sorta like a watercolor on silk. Any ideas? I thought crafty folks would have bosomed help.