Basically Ken has said it all. I too have about thirty bottles and have experimented with all but the latest DAK and NATO sets. A matt or satin clear is best for the AK stuff. It is important to let the effects dry before applying the next one, or they will mix and the previous work will be lost. I normally wait an hour or two then I apply an acrylic clear flat to seal the effects, then I continue with the weathering, sealing in between. I'm usually in a hurry and don't want to wait for things to dry. If you apply a lot of diff effects it wouldn't hurt to apply an occasional acrylic flat.

Cheers

Rob