Soak the pot in a tub of warm water for up to an hour, then scrub it with a stiff brush. Put the paint for the base coat on a plastic plate and thin it with a small amount of water. Apply the paint with a foam brush. Apply additional coats until the desired color depth is achieved. In my experience, acrylic and spray paint are both paints suitable for terracotta pots. For this project, I'll be painting terracotta pots with acrylic craft paint. But I have used spray paint for clay pots before too, and it works just as well. Acrylic paint is not really waterproof. It is water resistant to a big extent since it is a polymer. But is porous so it will absorb water little by little. Once the sealed clay pot is dry, it is ready to be painted. For flower pots that will be used outdoors, use either FolkArt Outdoor or FolkArt Multi-Surface Paint. The paint on your walls, vapors from cleaning solutions or even the pots where your plants live may be killing them. Researchers at Central Florida Research and Education Center have confirmed that paints containing small amounts of mercury will cause certain plants to lose their leaves.
Soak the pot in a tub of warm water for up to an hour, then scrub it with a stiff brush. Put the paint for the base coat on a plastic plate and thin it with a small amount of water. Apply the paint with a foam brush. Apply additional coats until the desired color depth is achieved.
Oil based paints have solvents in them that vaporize while drying, and these can harm plants, but should only be applied in well ventilated places anyway. Latex/acrylic/emulsion paints are waterborne and should pose no problem while drying, even indoors.
Water-based acrylic paints are ideal for terracotta and are convenient to work with. Latex paints are also a good choice for similar clay pots. Apply one coat of paint to the pot and allow it to dry completely before applying another coat. Terracotta is porous and will absorb the first few layers of paint quickly.
Chalk Paint is a type of paint (actually, it's a trademarked brand of paint by Annie Sloan, but other companies have similar paints also) that can be used on furniture and other items to create a chalky appearance. It's used for creating an aged appearance, and can be distressed easily.
Re: Painting over glazed pottery Make sure the surface is perfectly clean. Give two coats of Acrylic Sealer, making sure you dry thoroughly between coats. Then paint two base coats with Acrylic Paint, drying first coat thoroughly before applying the second one -- like 24 hours.
Sealing terracotta garden pots If you are using these pots for plants that have high water requirements or don't respond well to the wetting and drying cycle, sealing your terracotta pots is worthwhile. You can either seal the inside or the outside of the pot.