Really, you should be using Terry Wise’s Airfix rules …😄
I have Airfix type 1 8th Army & DAK. I don’t varnish because I use acrylic which forms a mini gimp suit around the figure and won’t crack like old enamels. The trick is to make sure the figures are covered top to toe and there are no gaps. Indeed, Type 1 Airfix were robust figures anyway and my original 1969 box of 8th Army I painted in 1977 or thereabouts are still in good order. They are at the top of the page here: http://battle77.blogspot.com/2019/08/little-acorns.html. Later figures with spindly weapons would flake enamel by harsh words alone.
Now, it’s acrylics all the way for me and I only varnish metals (and I use special metal primer too).
Apologies for hijacking the thread!
More nonsense on my blog: http://battle77.blogspot.com/