In both of these photos, a gel which has completely polymerized has been lifted up out of the casting tray and is now ready to use. Notice the spaces (called "wells") left by the removal of the comb. This can be seen better in the second photo.

Both gels are still resting on the glass support, and would be far too flimsy to rest as they are if not for the support. Notice the bluish tint to the gels. As agarose polymerizes, it takes on that coloring. This is often used as an indicator that the gel is ready to use. The higher the agarose percentage, the bluer the gel. Which of these gels do you think has more agarose in it?

By the way, the grasshopper, while cool, is not to scale...

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