Applying underglaze over the top of glaze. There were some comments a week of so ago about doing this and it seemed the opinion was "don't do it, it won't work".
Here are two mugs, with a ^6 white glossy glaze and stencilled over the glaze is Amaco Velvet underglaze. The effect is exactly what I wanted. Not solid, but stippled. The file size makes them look much worse than they really are.
And these two didn't crack. They are for Essex Young Farmers to sell for their own funds or to help with #Forageaid for the flooded Somerset Levels. Now I know it works, I've got to make a whole load more.