Reply to Flattening WHITE vinyls

Hi guys. Here's the thing:

I bought 2 traktor timecode vinyls. They are pretty warped. I want to flatten them.

I watched videos like this one from qbert: http://www.youtube.com/watch?v=UfcLZRr4VDU

The thing is: That works cause vinyl is black, but as you know, white reflects sunlight, so it doesn't get heat up as it should.

So then, maybe I should use the oven technique, but i don't know exactly for how long and how much weight i should use. Or maybe any other technique I'm not aware of?

How do you flatten your white vinyls, or vinyls in general?