Kryptonite comes in many colors.

In the comics Gold Kryptonite permanently removes Clark's powers.

In Smallville Blue Kryptonite temporarily removes Clark's powers while he remains in proximity.

Suppose the was a form of Kryptonite, call it prism K, that temporarily removes Clark's powers but only until his body could fully recharge, say in three to four years. Yes I said years.

So Trask finds this not Green K., he also finds blue K and Gold K. What he uses on Clark is his small supply of prism K, which in the aftermath is lost. Also lets say that exposure to this prism K renders Clark immune to Gold K but not Blue K.

Now it is a few years down the road and Nor and his minions invade and are defeated with Gold K.

What would Lex Luthor think if Superman were to suddenly disappear? What would Lois think? What would the world think?

So how does Zara and Ching, let alone Tez find Kal-El when he doesn't have any powers? We know that Nor would be interested in defeating Kal-El no matter whether he has powers or not (easy pickings), but if Superman doesn't show up for several years after Trask attacks Smallville wouldn't his minions come out and make Trask a martyr or something when Nor and his cronies invade? An invasion without Superman there to defend Earth would make it impossible for Clark to return as Superman when he finally regains his powers? Would he then return later on as some masked hero (ala Batman), so that he could help out when his powers return?

Also, on Smallville didn't the Blue K wipe out the powers of Kryptonians raised under a red sun? (Really got to finish S9).

Interesting. In the comics, Blue K has no effect on Superman, but it hurts Bizarro in the same way that green K hurts Clark. (In the comics, blue K was an imperfectly duplicated version of green K.)

Kryptonians appear to be telepathic even when they are non-super; I would imagine that Zara would be able to find Kal-El by mind linking with him.

Joy,
Lynn

I remember a saucy N-Fic where Blue K was used to make Clark impotent. "The Big Couldn't" by ML Thompson. Very Nice...