Well, things have made a turn for the worst.
I decided to skip the gloss varnish entirely, and just use Purity Seal instead.
It was a disaster.
My Skitarii with the paint scheme I was very proud off look like they passed through a blizzard.
Don't know why it happened. The can hadn't been used for a long time (though I did shake it for just under a minute). It had rained that day so perhaps the moisture level in the atmosphere was high. Or perhaps I applied too much (while spraying, it was hard to see how it distributes over the model), as I saw no misty effect when spraying, but it appeared with a vengeance afterwards.
Adding a layer of Gloss Varnish or 'Ardcoat did not help. However, I've had some success with applying olive oil. Covering the affected areas (i.e. the entire model) in olive oil, letting it set for a hour or so, followed by vigorous brushing with a drybrush removed most of the chalkiness of the brushed areas while keeping the paint intact. It is labor-intensive, as after a single treatment there are still many white areas left, so I will probably need to repeat the procedure twice. The main issue here is that after you applied the oil, the white areas are no longer visible so it is impossible to see which surfaces are clean and which still need cleaning/brushing. Only after washing off the oil and drying the model can you see which areas are still affected.
Edited by Quantum, 13 August 2019 - 06:55 AM.
"The Nova Terra Interregnum has been remembered unfairly by those few who remember it at all. True, many malcontents, provocateurs and petty lordlings flocked to its banner when it seceded. But its attempts to contain the aggressive expansion of the Ecclesiarchy were born from an honest desire to uphold those values at the hart of the Great Crusade. It is ironic that the last gasp of the Emperor's true vision was finally throttled at the hands of those who fought in His divine name, on the planet that once reminded our Lord of 'Urf, long ago...'"
- Archivist & Historian Vedek Parsen, pilloried, emasculated, hung, drawn, crucified, quartered, burnt and disintegrated for heresy extremus. Probably in that order.