Over the past few years I've run a (very) small business called Painted Trillium (after a local variation of the trillium flower) where I paint and sell slabs of stone for the home and garden. Well, the profit margin was great when I had time to deal with it, but I've had to let things fizzle for a while. Since I don't think my 'business secret' is in any danger from competition on this site (no one lives in my area, from what I can tell!) I thought I'd share my technique, and see if anyone else gets inspired from it.http://www3.sympatico.ca/anne.whitcombe/ladyslip.jpg
I bought slabs of stone from the local garden/landscaping centre --- they gave me great deals on pieces that had broken off of larger tiles, so I could usually get about a dozen stones for about $15. Limestone's the easiest to work with, because it's smoothest; sandstone's not bad either; but granite and quartz are very rough to work with. I took them home, laid them out in the driveway and hosed them off (really dirty ones got scrubbed with TSP and rinsed off again), and let them dry.
Then, using a dark drawing pencil (6B or so, to really show up on the rocks), I sketched out my drawings. I gathered images from field guides --- my focus was local flowers, leaves, and butterflies, for the most part. I realle enjoyed finding the best place on the stone to put the picture, using the natural layers of the rock to add depth and interest.http://www3.sympatico.ca/anne.whitcombe/dogwood.jpg
Once the image was plotted out, I used plain acrylic craft paints and cheapo (but fine-tipped) nylon brushes to paint the picture. (Painting on stone is hard on the bristles --- go figure!) To make the image really "pop", I used some diluant (a thinning medium for acrylics) and a little bit of black paint to make a transparent shadow effect around the edge of the image, so it looks like it's hovering a bit above the stone.
Finally, I sealed the whole thing with concrete sealer, which comes in big jugs for a few bucks at the hardware store. This not only protects the paint (if water seeps underneath it, it would peel), but also gives a nice glossy shine to the painted areas. The rock itself doesn't turn shiny, don't worry.http://www3.sympatico.ca/anne.whitcombe/daisy.jpg
We've had a number of these stones sitting out in the garden at home (even during brutal Canadian winters) for about 5 years now, and they're only just showing signs of beginning
to fade. I suppose you could use outdoor acrylic paints, which might last a little longer, but I can't see the need...http://www3.sympatico.ca/anne.whitcombe/monarch.jpg