You will need:

What to do:

  1. Put three liters of water into a bucket or other container.  A wide shallow container is best.  You will need enough room to lie your piece of paper on top of the water.
  2. Put 1/4 teaspoon of cream of tartar into the water and stir it in.  Leave for 30 minutes.
  3. Drop a small amount of oil paint into the water.  Does it spread out across the surface without clinging to the sides of the container?  If so, that's great news.   It means you have the right amount of cream of tartar for the water in your region.   Go to step 4.  If the paint did not spread out across the water, you need to add a bit more cream of tartar.  Add a generous pinch of cream of tartar, stir it in, wait 30 minutes and then test the water again.  If the paint spread right to the sides of the container and then stayed there, you probably have too much cream of tartar for the water where you live.  Add a cup of water and then test the water again.   If the paint still clings to the sides, add more water and keep testing until the paint spreads out smoothly across the water without sticking too much to the sides.
  4. Drop small amounts of oil paint into the water.  Use different colors and place drops all around the surface of the water.  Use a stick to very gently stir the drops so that they make nice patterns on the water.  Don't stir too much though, or you might ruin the effect.  When the surface of the water is pretty much coated with paint, lay a sheet of paper on top of the water, then lift it out.  WOW!  You should have an amazing marble-effect painting like the one pictured at the top of this page.