And the winner is – Humbrol Acrylic Spray Number 135 (Satin Varnish)!
My biggest problem with most of the varnishes I tried was that either they were too glossy (I like a satin finish) or that the level of gloss seemed to be inconsistent from figure-to-figure. Several minis suffered extremely glossy coats during my experiments!
Thankfully, the last varnish I tried from my orders is giving me some great results. I’ve separately sprayed half-a-dozen minis so far, and all have a resulted in an even, satin finish.
So, for the moment, I think my search has ended. I’m still ready to go back to Testors should a supply become available, but I’m happy to use the Humbrol at the moment.
The can suggests spraying at a distance of 20 – 30cm, but, if you try it yourself, I suggest giving it a bit more distance than that, as it is a very powerful spray.