There is something creative and magical about slip and the numerous things you can do with it. It is such a fun expressive medium to work with. Slip can also be referred to as a slurry. It plays a vital part of joining, decorating and creating ceramic pieces. Here is a list of questions answered about clay slis.
Slip is an exciting and daunting medium because there is such potential. You can use slips in many different ways which can be exciting but yet daunting. Lets learn more about clay slip.
- What do we use slip for?
Joining: Slip is essentially liquid clay. Slip acts as an adhesive by bonding the two pieces. It moistens the clay and once the clay dries in the scored marks it helps make the bond even stronger.
Decorating: You can use colored clay slip to create cool effects. Depending on how thick you make your slip you can create different textures. You can use slip by slip trailing, brushing on slip, sgraffito on slip and so much more.
Slip casting Slip: Slip can be used to actually make pieces. We will explain how this works a little more in depth later in this post. Slip casting is the process of making pieces using plaster molds to dry out the liquid clay to make pieces
2. How do you make slip
There are several ways to make slip. The simplest way to make slip is to get some bone dry clay and water. break up the chuncks of dried clay and mix the water in varying amounts to create slips with different consistencies. Basic slip is usually the consistency of yogurt or sour cream, this is mainly used for joining and sometimes decorating. Slip can also be very liquidy for example when using it to do slip casting.
3. Is underglaze and slip the same?
Slips and underglazes are similar, but not the same. Underglazes can be used on all stages of greenware and also on bisqueware as it contains some frit. Frit is a mixture of silica and flux which aids in the bonding of underglaze to the pottery. Not enough frit to form a glass-like seal but enough to make it workable for bisqueware and greenware.
4. Trying to make slip, but I don’t have a immersion blender or blender. Is it fine if my slip isn’t very smooth?
If you don’t have a blender the best way to make slip is to take some bone dry clay and place it in a Ziploc bag. Use a rubber mallet or hammer (preferably a rubber mallet) and smash the clay until it is very powdery. Do this inside the bag and wait a few minutes before opening as you don’t want to breathe in silica which may cause silicosis. Add water to a container and let it slake (sit) overnight. You may also want to strain it if you are able too.
5. What are the benefits of using vinegar and why?
Vinegar is useful when making joining slips. Vinegar is a flocculant because it helps make things stickier. It also has antifungal properties, which helps prevent mold from growing in slip when it is stored for awhile.
Recipe for joining slip:
Things needed:
- Pint container
2. 4 sheets of toilet paper
3. White vinegar
4. Clay
5. Immersion blender
Instructions
- Use an immersion blender, mix pulpp
2. Break bone dry clay pieces up in a container
3. Mix into the solution
4. Vinegar may foam
5. Mix again
6. Can You Use Fresh Clay to make slip if you don’t have bone dry clay?
Even though bone dry clay is better to make slip, you can still slice off pieces of fresh clay and let it dry out. Break it up and make the slip.
7. Making slip with Wet Clay
Not recommended to make slip with wet clay. It takes longer because it is not absorbent and will not absorb water as easily.
8. Making Colored Slip to decorate your pieces
You can learn how to make colored slip and more information about it here: https://kevinsceramics.com/?p=408
9. When should I add Mason Stains to the slip?
You can use bone dry clay and add water to mix it up to the correct consistency. Then you can add the colorant.
Alternatively I like to weigh the bone dry clay, add 1-10% mason stain to the clay mix that up dry, and in another container add 70-100%, and then add the bone dry clay and stain to that.
10. Do you need a coat of clear or semi-transparent glaze over slip decorations?
If your piece is sculptural or decorative you don’t need to add a clear glaze. If you are using a high fire clay (cone 10 or higher) and it is fired to temperature, vitrified, it makes the clay waterproof and thus food safe.
If your clay is not cone 10 or higher and you don’t want to glaze your slip decorations but want your piece to be water tight, remember to glaze the inside after it is bisque fired.
11. Can I apply Slip to Bone Dry Clay
The short answer is YES… The long answer is it depends. It is best to wet it down before adding the slip but if you want to add the slip to bone dry clay find a slip recipe that is made for bone dry and bisque. You CAN NOT use your clay body to make this slip. You can find many bisque and bone dry slip recipes online. Either way it is a good idea to use thinner coats of slip on bone dry and bisqueware.
12. Can You Use Slip-on Bisqueware
The short answer is yes. The long answer is kind of. You can’t use the slip made from your clay body to make the slip. You need to find a recipe online for bisque slip which is usually made to go on both bone dry and bisqueware.
13. What is slip trailing?
Slip trailing is a technique where you can apply slip with or without a colorant onto leather hard clay using a slip applicator. You can find out more about slip trailing here.
14 What are the different ways I can use slip?
The short answer: slip trailing, slip transfers, mishima, embossed slip, joining slip, and brushing on colored slip. To learn more about the different ways to use slip read this post.
15. How Do You Thicken Slip?
If your slip has too much water there are a few ways you can rectify this issue.
- Wait for the water to evaporate
- Let it sit and pour off the access water on top
- Add some bone dry clay to the slip and blend
- Add an epsom salt solution (add some epsom salts to water)
16. Slip is too thick
If your slip is too thick you can simply add water and shake it up
The other way to thin slip out without adding more water is by adding a deflocculant.
16. What is slipcasting?
Slip casting is the process of turning liquid slip into a clay piece. This is done by placing slip into a plaster mold and waiting a little, pouring the slip out, and demolding. The way slip casting works is relying on two things: plaster, and slip. Plaster is a very absorbent material and when you add slip into a plaster mold we rely on capillary action to help us. Capillary action is defined as the tendency for a liquid inside an absorbent material to rise or fall as a result of surface tension. In this case the liquid is slip and the absorbent material is the plaster. Once the plaster has soaked up some of the moisture from the slip it becomes clay. Pour the rest of the slip out of the mold and you have got a shell which is the piece. Slip casters commonly use soda ash, sodium silicate, or Darvan 7 as deflocculants. You can buy gallon jugs of casting slip read-made or make your own.
17. What is the difference between joining slip, decorating slip, and casting slip?
Joining slip is meant to help bind two pieces of clay together. Decorating slip is similar to joining slip, however, you don’t generally add paper or flocculants to it but you generally add stains to color it. Casting slip is used for slipcasting and because of the process of slipcasting you don’t want to incorporate too much water into casting slip. To make casting slip we instead rely on deflocculants. A deflocculant is a solution that makes clay more liquidy or runny without introducing more water/moisture.
18. Can you make slip using several types of clay?
Working with multiple clay bodies means working with different shrinkage rates and iron content. This may lead to problems with your desired piece. Different clay bodies fire at different rates and/or produce different colors.