Always clean your stencils (and brushes) immediately after use.
If you are stenciling a long project (such as a wall), periodically wipe paint off the stencil with a damp cloth or sponge to prevent the paint drying on the stencil. (Be gentle and don’t bend the cut-out design). When you have finished stenciling, give your stencil a final clean.
Cleaning a stencil will depend on what type of paint you have used: oil-based or water-based paint.
If you don't know what type of paint you are using, the paint can, or bottle will likely say if it is oil or water based. If it doesn't, one clue would be if the paint is flammable, most oil-based paints are flammable, while water-based paints are not. If you are still not sure, an easy test is to run your used paint brush under some water. If the paint dissolves in the water easily it is water based, if not then it is oil based.
We normally recommend acrylic paints for stenciling, which are water based.
The easiest way to clean a stencil is to immerse the stencil in hot water, and let it soak for about five minutes. The paint should soften and swell and can be wiped off with a cloth or a soft bristle brush.
Be gentle when wiping off paint to not bend the cut-out designs.
Thoroughly clean all paint off the stencil, so that it can be used again and again.
Dampen a cloth or sponge with turpentine or mineral spirits and gently rub off the paint in small circular motions.
Be gentle and don’t bend the cut-out designs.