How much sodium silicate to use?

[Julie Bergeron]

I want to make thick slip for slip trailing and surface decoration from my  em 103 low fire clay. I do not have a scale to weigh chemicals or how to determine specific gravity, I know that I need to add a defloculant, but what kind and how much?

Thanks

[Min]

To thicken up slip you can dribble in a tiny bit of darvan then add some more dry powdered clay until the slip reaches the consistency you need. Just add a tiny amount at a time, for a couple cups of slip you might only need 1/2 tsp so go slowly, mix then add more if necessary. John Britt video showing this:

 

[neilestrick]

An easy way to make deflocculated slip:

Completely dry out a bunch of your clay body and break it into chunks. Put the chunks into a container and completely cover with water by a few inches. Let it sit overnight. In the morning, without stirring it, pour or decant all the water off the top. What you're left with will be a very thick slip. Use a stick blender to mix it a bit, which will be difficult because it's so thick. Then take your deflocculant, either Darvan or sodium silicate, and mix it with an equal amount of water. For small container you'll probably only need a teaspoon or so. Drop by drop add it to your slip and blend it to smooth it out. You'll see it thin out a little bit with each drop. When you get to the consistency you want, stop! If you go too far it will eventually go whoosh and become super watery. Go way too far and it will seize up like bad chocolate.