The clear goes on first to create a perfectly smooth top coat on the playfield before paint and decals.

Think of it like this: It's a layer, like in photoshop. Where virtually anything can be done, and UNDONE, without damaging the playfield underneath. Once you're complete with all the touchups, you lock it in with your final thicker layers of clear to protect it for an eternity.

This is precisely why proper playfield repair isn't for everyone, and why there are more shoddy repairs all over the place. If you're going to do it, do it right once. If you can't do it right, don't do it at all...or alternatively, pay someone else to do it.

The bottom of the playfield doesn't need to be cleared, but yes. Obviously you can use a little clear to repair a small portion of the field if you want to. But anytime I've seen a playfield "touched up" with clear, it usually looks like s&*t. I'm not sure why you wouldn't want to clear coat the playfield anyways...every playfield should be cleared imo. It protects it forever.