i have been using clear basecoats for a few years now especialy for silver blends in fact for most blends as it allows for a much heavier scratch and i also find that with a full base foundation the clears lays nicer than on plain sanded factory clear with far less risk of runs sags and an uneven finish as in my experiance fresh clear doese not lay the same over old clear as it doese over newly aplied basecoat
my process is to sand out the whole panel inc the blocked repair with 400 to 600 on a DA ,lay the clear foundation coat over the whole panel but keeping within any clear blend areas, colour up the repair then add 50% base binder to the colour to fade out with ,any more than 50% and your risk issues with the pearls floating as with a contaminated clear coat ,i think we have all experianced metalics floating in clearcaot due to a poorly washed gun at some stage of the game
as i mainly do custom work i use a lot of so called intercoat clears or control binders as i prefer to call them ,their main use for me is as a candy dye carier, metalflake carrier and for other trick Tricoats ,for airbrush work i use them to extend my colour prior to thinning in order to reduce the pigment loading and mantian a decent binder to thinner ratio at the same time
once you have learned to embrace the use of a control binder such as DBC 500 you will wonder why you struggled on without them before
Paul