Making backgrounds with shaving foam is real fun. For this technique you need (see photo 1): the cheapest shaving foam you can find, a deep tray, water based liquid paint or food colors, a stick or toothpick, a palette knife or an old credit card, cardstock (not glossy).
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Spray the shaving foam into the tray and spread it with the palette knife to an even layer of about 1 inch (2.5 cm) thick (photo 2). Drop some paint on the surface of the foam (photo 3) and swirl the colors around with the stick (photo 4).
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Place a sheet of cardstock on top of the shaving foam and press on it to make sure the sheet is touching the foam. Gently peel the cardstock off the foam and lay it on a flat, hard surface (photo 5). Remove the shaving foam from the cardstock with the palette knife (or credit card) and a paper towel. Let the cardstock dry (photo 6).
Place another sheet of cardstock on the shaving foam and repeat the steps.
After peeling the cardstock of the foam (photo 7) you can place another sheet of cardstock on this sheet so you use 'both sides' of the foam (photo 8).
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With this technique you can make a lot of patterns by mixing the paint and foam in different ways.
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Made this card with a shaving foam background.