Two other types of adhesives are worth considering when you make a collage. Polyvinyl acetate adhesives (Lineco or Jade 409) aren’t waterproof but have the advantage of being less shiny. This means they’re less visible than gloss medium and epoxy. Epoxy, on the other hand, is stronger than acrylic medium and sticks to almost anything. This means it can be used for fastening solid objects—including metal and glass—to collages. Note, however, that epoxy darkens with age and therefore must be hidden behind glued objects or covered with paint.