Most of my collages and paintings are on canvas. Lately I have been including hardboard and spray paint. I like the smoothness and glossiness of the spray paint. The problem with incorporating the spray paint, matte medium (for the collage part), and the sealing iron is that it bubbles:
I’m not sure if the bubbling is because I burned the paint or if the sealing iron-matte medium-hardboard combo is too touchy.