Thanks for replying

I've now got the hang of spraying with a water based aerosol

, i've now taken the mirror covers off, done the blue base coat, let it dry for 6 hours in a sealed cardboard box above the cooker

I've now applied 5 coats of acrylic laquer, wet flatting between each coat of laquer.
I'll be leaving the laquer to fully harden for 6 or so days, then i'll wet flat the whole mirror covers with 2000 grade paper, then polish them up to look like glass

i'll post a few pictures of the outcome of these second hand mirrors very soon.
ian.