Hi Brendan, If I wanted to add to a slip cast item I have made, is this the clay that I should use to add to said item?
That is correct yes.
Hi, I assume this comes as a solid block. How much water should I add? Should I add any other ingredients?
Yes this is a plastic clay. To make a casting slip we recommend a basic recipe of
23.5g Sodium silicate 75's
This may require adjusting based on your water hardness etc.
Or you can buy it ready made
Hope this helps!