How To Make Clay Slip

Slip, also known as a slurry, is a liquid mixture that has many uses in the production of pottery and ceramic items, it’s an essential tool I use all the time and the best part is its easy to make at home by recycling your offcuts of clay.

How do you make slip? First make sure to use the same clay that you are using to create your project.  Break up dried clay and add to a beaker until the beaker is 70% full.  Add room temperature tap water to the same level as the clay.  Add a shot a white vinegar and shake up.  Stir using a stick, then leave to stand for 15 minutes.  Shake again and stir for 5 – 10 minutes until it becomes lump free and a cream consistency.

This method takes around 15-20 minutes and will give you beautifully smooth slip.  Let’s take a closer look at the process and what you can do with the slip once created.

To make clay slip your will need:

• Clay, the same type that you will use the slip on 
• Beaker / plastic container with lid
• Room temperature water 
• Stirring stick 
• Mask (to protect you from clay dust) 
• White vinegar 

I use porcelain and I make slip out of offcuts or broken items.  This is a great way to reduce waste, if you’ve made a mistake or had an accident the item can be recycled into slip for another item, providing the item is using the same clay type.  

You need to use the same type of clay to make your slip as the item you are making, so porcelain for porcelain slip, stoneware for stoneware slip etc, to ensure the slip fires at the same temperature as your item.

5 Steps to Make Pottery Slip

Making slip is very easy:

1. Break the dried clay up and add to a beaker or plastic container.  Fill the beaker up to around 70% of its capacity with broken clay
2. Add room temperature tap water.  The water should cover the clay, but not fill the beaker.
3. Now for the secret ingredient, add a shot of white vinegar, this helps to break down the clay and create a creamy thickness.
4. Put the lid on and give everything a good shake. Leave to stand for 15 minutes before vigorously shaking again.
5. Pop the lid off and begin stirring the mixture until it thickens into a cream-like consistency. This can take 5-10 minutes if constant stirring so don’t give up.  

If the slip is too wet you’ll need to add a little more clay, if it’s too thick add a little more water, stir until the slip consistency is like pouring cream.

How to make coloured slip

To make coloured slip you can either follow the above process but using coloured clay, or if you’ve already made slip and want to colour it you add a coloured stain or oxides as step 6 and mix it in to give a consistent colour.  This can be useful for decoration, which I’ll talk about below.

How to make a LOT of slip

I only need a small beakers worth of slip as my items are small.  If you need to make a large quantity of slip you can follow the same process but at a larger scale, replacing the stirring stick with a good drill with a mixing attachment to ensure the slip is creamy smooth.

What is slip used for in pottery?

Slip is a very versatile potters tool with three mains uses:

• Glue
• Decoration
• Casting

Using slip as pottery “glue”

As a slab builder my primary use of slip is to bond my pieces together.  For example, if you have decorative flowers you want to attach to a mug you would first score the flower and where on the mug the flower is to be placed, then paint slip onto the flower and mug.  Place the flower on the mug and the slip will act as a joining glue, ensuring your decorations are secure.

You can also use slip to join two halves together, as I do in my ceramic pumpkin project.  After creating two halves of a hollow ball the edges are scored, slipped and placed together to create a single object.  When joining two pieces of clay together remember both need to be wet, this helps you slide them into the correct position and aids the bonding process.

Decorating pottery with slip 

Slip, especially coloured slip, can be used to decorate your items.  As a liquid you can use slip the same way you’d use paint, it can be applied via a brush, be sprayed on or your item can be dipped into a large container of slip.

The use of decorative slip opens up many creative possibilities and can allow you to create very intricate and unique designs on your items.

Casting with slip

Slip casting is the technique of pouring your slip into a plaster mould and left to dry.  When the mould is opened you have a sollid item, for example a mug.  Plaster moulds come in all different designs and allows for quick mass production of items.