Start with a layer that has the image you wish to stencil spray on it. In this case its called sprayme

Duplicate this layer, then use the Filter > Distort > Ocean Ripple filter on it with the settings below

On the same layer use the Filter > Blur > Radial Blur option. Make it zoom blur and position it to where you want the spray angle to be.

Duplicate this layer a couple of times, then merge all three of them together to get a nice dark effect.

On this layer go Filter > Noise > Add Noise use the settings below to add a monocromatic granular effect.

Set the mode to multiply.

Now duplicate the original layer again.

Now add a nice fat gaussian blur from Filter > Blur > Gaussian Blur to it

Duplicate this layer and then merge them both together.

On this layer go Filter > Noise > Add Noise use the settings below to add a monocromatic granular effect.

Set the mode to multiply.

Now position the 3 layers in relation to each other to get a aesthetically pleasing effect like the spray effect at the top of this tutorial.

Added: December 02, 2003