Merridan uses a variety of techniques to build up images in inks, oils, acrylics, water colours, pencils and pens. He begins his work with an idea in mind. He pours and manipulates the ink or paint and then works into it with the pens highlighting details.

He sits back, observes his work and then works into it again. There is a large element of Pareidolia in the work. This is a psychological phenomenon involving a vague and random stimulus (often an image or sound) being perceived as significant. Common examples include seeing images of animals or faces in clouds, the man in the moon or the Moon rabbit.

In Merridan's work observers often claim to see seemingly hidden images when observed closely.