How to Make Better Clay Joints: Scoring and Slipping

When you score and slip, you connect two pieces of clay together better than you otherwise could. When making a handle for a cup, joining coils, making a foot, or making a serving bowl, you want the clay to stay together. You might have noticed that it’s easy to stick two pieces of clay together and it looks fine until it dries and the two pieces pull apart. Making a better joint starts with giving the two surfaces some texture and getting both surfaces to the right consistency so they can stick together.

To score, scratch the surfaces where the two pieces will connect. You can use a needle tool, a serrated rib, or any number of other modeling tools to scratch a series of shallow lines on the clay. Don’t worry about cutting into the piece too deeply; you just want to make enough scratches so the two pieces can grab onto each other. You don’t have to score only one side of the connection. Remember that there are two sides to every joint!

Slip is a watery version of the clay you’re working with. It goes in between the two scored surfaces. You don’t want too much slip because it can weaken the clay nearby and cause the handle to fall off. It should be just enough to fill the scratches and no more. After scoring both surfaces and putting slip on them, press the two sides together. You want enough slip to squeeze out between the two sides of the joint but not so much that it creates a weak connection.

If you’re having trouble getting your joints to hold up well, try experimenting on some smaller pieces of clay first. Make some small flat pieces or short coils and see how they respond to different connections. Try sticking them together by hand. Then try connecting two pieces after you’ve scored them. Now try connecting them after you’ve scored them and added slip. Let all of them dry out slowly and then see which connection feels stronger. You don’t have to break them apart to test them, you just want to see how much more connected the pieces are after you’ve given them the proper tools to hold themselves together.

Make sure the two sides of the connection aren’t too far apart in terms of their consistency. If you put a very wet handle on a stiff cup wall, the handle will dry and shrink at a different rate than the wall, causing stress around the connection. They don’t have to be exactly the same consistency, but they shouldn’t be worlds apart either. If one piece is softer than the other, wait until it firms up a bit so it’s easier to position and won’t get distorted when you put it on the cup.

Once the pieces are attached, compress the seam rather than smear it. Use a finger, a small modeling tool, or a rib to push the seam into the surrounding clay. You’re trying to hide any gaps and smooth the edges so the connection is as seamless as possible. Don’t go back and add water over and over just to try to smooth out the seam. Even if it looks good on the surface, the connection could still be very weak if the clay wasn’t properly scored, slipped, and pressed together.

After connecting the pieces, look over the connection from a few angles to see if it looks okay. Are there any open seams? Is there any spot where the handle is peeling away from the wall? Is the connection very thin? Do a quick stability check on the handle, just enough to see if it holds up but not enough to stress it. If it looks like it’s already falling apart, fix it now. Don’t trust the drying or firing process to fix the problem for you.