Last night I was daubing away (for the first time in a couple of weeks) on some half-finished 15mm Hobilars, finishing off their straps and saddle-work. For some reason I couldn't work out it wasn't going well. The paint texture seemed wrong and the paint was clumping slightly as it dried, but only when using my really fine detail brush. I gave up as being 'too tired' and came back to them tonight. Oh dear. I decided I'd strip and restart, but still couldn't work out why - the same paint and same brush were fine tonight on some Outlaws for LotOW.
Then I packed my stuff up tonight and worked out what the problem was - I have a couple of DIY brushes sitting in a jar beside my workbench. They are soaking in White Spirit. I had dipped my brush in the blasted stuff before starting last night and ruined seven cavalry that were almost done. My comment on that mistake was not very polite, but at least I'd rinsed my brushes carefully when I'd put them away last night so the small amount of white spirit had obviously come off and not ruined tonight's Outlaw painting.
Note to self - BE MORE CAREFUL. Sigh!