If you have any hobby shops in Australia (Hobbycraft in the UK, Michael’s in the USA) you should be able to pick up a decent spray matt varnish. I’ve tried Plastikote silk before and it’s a bit shiny (so slimy looking) but not quite as bad as gloss.
I’ve yet to try their matt but after the recent disaster with GW purity spray I shan’t be buying any more of that any time soon.
Living in the Top End, I’ve found that Purity Seal tends to leave a white opaic finish, totally ruining you’re hard work. If I do put a finish on my minis I tend to use “Microscale Ind, Micro flat”. I get mine on ebay. Not as convienient as a spray, but a little in a pallet and a drop or two of water mixed in and it gives quite a good finish without too much sheen, also it is non yellowing. It’s not ideal but it’s the best of the whole heap I’ve tried so far.:cheers
I haven’t used the purity because of the possible shiny effect, don’t know if I want or like it. and at least Uncle Fool’s solution can be sent to you through the post unlike aerosol spray cans.