Yes i use that one as described !Andy, it's the same varnish I've been using for the last couple of years, after Karl suggested it.
My original 60 ml ( 2 fl.oz.) bottle is nearly empty (cost, from memory, around £3 to £4 ), so I got this 500 ml (16.9 fl.oz) for £12 - heck of an overall cost saving.
I've found it works wonderfully, just thinned a bit with tap water for airbrush use ( I believe Karl uses it 'neat', applied with a brush), and gives a nice, matt finish, with a very slight sheen. Less thinning will give a very flat, matt finish and it only needs a small amount of the varnish to cover a Mosquito sized model.,
So far, I haven't had any problems with it, and only wish I'd tried it years ago, and I keep meaning to try their gloss version too.
It works well, like Terry says, matt with a slight sheen