Should you seal both sides of the ailerons and elevators or can you just seal one side like the bottom? Also, how about the rudder....any need to seal these?

Thanks in advance.

You need seal only one side, ie, the bottom. The rudder
is less critical but I always seal it.

Technically you only need to seal one side to make them not leak. But if you only do the bottoms, air can push through the top and push the covering out and it can peal off from my experience. On my giant scale planes I seal both sides so they don't "blow out". I also like to seal the rudder. I use my rudder as much as or more than any other control surface.

BTW, clear Monocoat works great on any color. But solid colors hide imperfections in the hinge job (gap-o-rama).

I would seal only one side, both if you can do a good job and want to make the seam invisible

I have Ultracote on my plane but would it be okay to use Monocote clear to seal the gaps? Also, does the material that one uses to seal just put in the gap or should it come out slightly onto the aileron and wing....for example?

Thanks in advance.

If you run smoke or glow, that tends to be oily, do both sides. this way oil wont seep under and peel off the sealing...