'Whaam!' is one of a large group of paintings based on comic strip images made by Lichtenstein in the early 1960s and which brought him international acclaim. Their subjects are almost all either of love or war and they constitute a fascinating, thought provoking and often witty compendium of images dealing with these topics of perennial human significance.
Like other leading American Pop artists, Lichtenstein was concerned to preserve as far as possible the essential character of his source material, which he did so successfully that many critics complained that he was simply enlarging the comic images. In fact, Lichtenstein's comic sources were painted by him in a fundamentally traditional way. He began by making a sketch of the scene, in much the same way as, for example, John Constable would sketch a piece of Suffolk landscape for later elaboration into a full-size painting. In the sketch Lichtenstein adjusts and strengthens the original composition, making both omissions and additions, and devises a colour scheme using the simple primaries of comic art but bearing no necessary relation to the original. The drawing is traced onto the canvas using a projector. The finished paintings, as in the case of 'Whaam!' are notable for their bold colours and often extraordinary forms, which while retaining a strong representational function, take on a life of their own as abstract and expressive shapes. Examples here include the black elements, like snake's tongues, in the flames of the explosion, or the extraordinary amoeba-like form of its yellow core. The highly stylised nature of this painting is also emphasised by its large scale.
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.242