Shade a cylinder with the airbrush and Surface Blur

 

Make a new file 640 x 480 pixels.

 

Make a selection for the side of an orthographic Cylinder.

 

Hit D to set your colors to black and white.

 

Make a rectangular selection.

Shift Back Space and fill with 50% gray.

 

 

Select one of the soft round brushes and size up to about 100 pixels.

 

 

Start with white.

Set the brush opacity to a low percentage, about 20%

Use the shift key to make horizontal lines of gray

 

 

Tips: If horizontal banding appears, use Filter/Blur/Surface Blur.

As you go on, vary the size of the brush, in general going down in size.

Hit X and paint with white, then black, then white, etc.

Set the brush to a lower opacity as you proceed, as low as 6%.

 

Lat tip: Make a little bit of lighter gray near the top and bottom edges to suggest reflected light.

 

Keep going at this until you get something like this image below.