@Mark T @Gary @Lucie Y and everyone – I just wanted to say how touched I am by your kindness. Thank you so much for the things you've said. I'd been really unhappy with what I'd done and came very close to putting it in the bin and pretending it hadn't happened, so I can't tell you how grateful I am.
@Lucie Y I've just seen your incredibly beautiful Fraktur in the other thread – I hope you're enjoying the course. Unfortunately, I think my problems with the Schmincke Calligraphy Gouache were caused solely by me! I tried Winsor & Newton a little later and mostly experienced the same problems. I was struggling to get a consistency that would flow from the nib but was also opaque enough to cover my pencil guidelines.
I'm still not sure I've sorted the problem completely, but I think it was mostly caused by a combination of Mitchell reservoirs (which, four years later, I think I'm only just getting the hang of!), writing at a slanted board (so most of the gouache was pooling at the bottom of strokes) and, well, my general incompetence! After using the gold gouache the other day, I'd like to try reintroducing the reservoir and maybe a slight angle to the board.
The only difficulty I found more with the Schmincke than the Winsor & Newton was the gum arabic separating out. With the W&N's, I mostly found I could just squeeze that top bit out and everything beneath was OK. With the Schmincke, it made a big difference when I stirred the inside of the most-separated tubes with a cocktail stick. (Maybe they were just slightly older?)
But I'm sure you'll love the Schmincke – it mixes to the most beautiful, creamy consistency. I must try out the deep red again – the light red (possibly Vermilion Red?) is my favourite of all their colours. It just pops off the page!