Unlike ordinary photographs, no two colourwash art photographs can be exactly the same. Here is why.
I print my photograph on thick, smooth, acid-free watercolour paper via an inkjet printer.
Then, moistening a watercolour brush, I apply a slight amount of water to each individual area of colour in the image, to move the ink and soften its effect.
Sometimes I use more water and then apply blotting paper to lift a colour. In parts of the photograph, I will supplement a colour, but mostly I use what is there already in the picture. The water application takes considerable care for the final effect to work well. It is very akin to the techniques of watercolour painting.
It is this combination of a gently softening effect of the water, coupled with the precise details of the photograph, which help to make a colourwash art photograph memorable, as well as unique.