This week at the studio, Otto talked about having made slip to use in plaster molds. A little piece he’d slip cast was on the work table when I came in. It’s been so long since I’d done any slip casting, it made me wonder what the ratio of clay to water should be, how it is made smooth enough to pour, etc. So, I found a couple of articles to share that concentrate on these aspects and more. I think the last time I did slip casting was with my Mom’s friend Nancy when I was seven or eight! Maybe it’s time to give her a whirl. Slip casting is a good article covering the process from start to finish and includes formulas. Basically, the ingredients consist of clay in dry form, water, water glass (sodium silicate). I’m a fan of allexperts.com and found some good information from one of their ceramic experts. He said, “any clay can be turned into a slip. Cut the wet clay up into small pieces and let it dry out completely. Put the dry pieces in a container and add water until it just covers the dry clay. let it sit, do not stir, you will be able to see the clay disintegrating as it absorbs the water. Within a few hours it will be ready, next day is better, mix up and use.” This is exactly what I wanted to know and I have some pieces I never bisqued for one reason or another. So, I think I’ll just break them up and follow Sam’s advice. Here is another site that gives good basic information. It is not an in-depth article, but covers the process of slip casting rather well. I cannot vouch for the veracity of the article, though, in terms of the length of time needed to mold a piece, because these articles have conflicting advice and I don’t know what to believe. Another article suggests 20-40 minutes, whereas the ‘another site’ article above says eight hours or longer, depending on the size. That sounds like an awfully long time. I guess I’ll just have to experiment and follow-up with Otto. I like the idea of slip casting something, then altering it to make it more of my own. Since a piece is leather hard when unmolded, I would still have the time to make changes. This video below on “Clay for the Slip Casting Process” gives more depth. Based on what this ceramist says, I would have to add a deflocculant like water glass or soda ash to make slip the right consistency. Also, I have to consider whether the clays I’m considering using are appropriate, a white and a red clay. According to the video, porcelain is a good choice. Because there are many questions still unanswered, I am going to have to ask the centre’s artist-in-residence more about slip casting to get a better idea and I will report what she says at a later time.