I had an interesting message from Tony Robertson, regarding my Largin' it post of a few days ago. He left a comment saying "In the original American edition that blue FX was not present. I always wondered if they made a mistake in the US edition by leaving it out, or someone in the UK got creative :)."
Tony then took it upon himself to get right to the source and contact Jim Steranko himself. This was Jim's reply.
"The psychotropic Dream Sequence in CAP 111 showcased several surreal special FX, including the optical shockwave behind Bucky on the second page. The color effect was achieved by means of an overlay on which the effect appeared. (The clouds on the previous page, for example, were suggested on my color guides.) Marvel press prep dropped the ball and printed the page without it; Marvel UK got it correct. Since the UK operation was only given film, rather than originals, with which to work, how they achieved the effect is a mystery--one of many regarding my material."
So there you have it! Jim Steranko explains all.
Nice one, Tony!