To clean brushes after painting over-glaze paints use 91% isopropyl alcohol or denatured alcohol, mixed 50/50 with lavender oil.
You can use each alone, whatever works for you.
Also pure grain alcohol from liquor store will do the job.For oil paints (oil based china paints are included) turpentine ( or turp's substitute Durotine) and "Liquin" Winsor & Newton work. linseed oil is used to thin the oil paint down. White spirit is good dissolving agent.
More brush cleaning tips are here
