Officially? Not to my knowledge.
Unofficially—I remember a comment once that Ray Palmer couldn't enlarge himself any more than his natural height and weight, but can't recall off hand exactly when/where that statement was made. I do think it was in the letter column of a Julius Schwartz overseen title though.
Hope the above helps.
The Atom's early stories spoke of Ray Palmer's experiments in matter reduction. He was never trying to enlarge objects bigger than they were. His size and weight controls were powered by the white dwarf star fragment's radiation. The more he used, the smaller he got. By reversing the radiation whether by lessening its charge or draining it, he grew back to normal size, unable to get larger!
He was using matter from a white dwarf star, so naturally he got only smaller. Things might have been very different if he'd used a fragment from a red giant instead!
Interesting. Thanks, guys.
My favorite bit in The Atom's origin is when a fragment of a white dwarf star lands on Earth, coincidentally near Ray Palmer, especially coincidental since it's exactly what he needs to make his experiments successful.
"So heavy — I can hardly lift it!" he says.
Yes, Ray. It would be heavy. Very, very heavy.
From Wikipedia: "A white dwarf is very dense: its mass is comparable to that of the Sun, while its volume is comparable to that of Earth."
The gravity of that chunk of white dwarf would probably be enough to throw Earth out of its orbit before it even got here, killing us all. Heavy, indeed.
Even by Silver Age comic book standards it was a rather huge chunck of creative license at work here.
Still, I find myself looking forward for some fun, contrived explanation for how come Ray Palmer can even survive the proximity of a White Dwarf fragment. Maybe he has some reality warping power and never realized it?