This is my recipe for coloured slip. Ball clay powder 35 parts;Kaolin powder 25 parts; Potash Feldspar 20 parts; silica 15 parts. I mix this into water (guesstimate amount), then when it has 'slaked down", i sieve it, and then it can settle so that extra water can be skimmed off so that the consistency is as you want it. I end up with a largish amount of slip, which I then decant into separate containers, and i mix different coloured underglaze powders into the different containers. I use this for painting on leather-hard ware. I have used it for banding onto the pot while it is still on the wheel, but you tend to contaminate the colours, as with each brushstroke, you are putting some of yr thrown clay into the slip bottle. This can also be put into little squeezee bottles for slip trailing. You will get used to what different consistencies you need for the different applications. In the beginning, I followed the recipe exactly, now I just use an approximation.