This is a small porcelain vessel I made, approximately three inches tall, showing one of the problems I had with painted underglaze.  The underglaze designs are a lot more detailed before the glaze is added.  Later I tried to correct this by spraying, which mars the design less, but ends up being thinner, which makes for a rough surface. After firing, to clean up the blurriness of the design, I painted over it with chinapaints and fired it again.