MM~
An easier method to try is to cut a piece of black paper or card to the exact measurements of the frame and insert it under the glass. Works like charm
Namaste, Gede...
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Persephone, Sweet-Lipped, Queen of Elysium, Priestess of Shadow, Renewed Daughter of Springtide...Your gift is light in darkness and shadow when the light sears...Goddess of my soul, let Magick be my guide~