Blog by @junimargrie
What are ceramic stains?
Commercial ceramic stains are a mixture of pigments and metallic oxides or carbonates and usually purchased in powder form. They can be used to add subtle or vibrant colours to glazes, slips/engobes and clay bodies. Traditionally, potters have used metallic oxides and carbonates such as cobalt, copper, manganese and iron, and blended them with opacifiers to make colourants. Dependable commercial stains are now used in preference to for a more predictable, consistent and stable colour. The variety of colours and tones you can obtain on your ceramics from commercial stains is limitless.
How can I use ceramic stains in my pottery?
Ceramic stains can be used in many different ways such as in the following examples:
1. Stains used in a base glaze
Stains can be added to a clear base glaze recipe. Stains added to a clear glaze can produce bright, vivid colours or more pastel shades. It is suggested to start experimenting with small amounts. It is possible to get a translucent colour (almost like a celadon effect) from mixing as little as 2% of stain into a clear glaze. Sometimes you might be surprised that as you increase the amount of stain, the translucent glaze then becomes opaque, and this is because of the addition of other ceramic materials in the stain like silica, alumina and opacifiers. Be careful not to add too much stain – a general recommendation is to stay below 10% – because too high percentage of stain used in glazes can create issues such with fluxing – this can manifest in crazing, or the glazes running more than expected. It’s also a good idea to sieve your glaze once stains have been added in order to reduce speckling.
2. Stains used in slips and clay bodies
A stain can give you great colour and vibrancy to your pieces by mixing them directly into your casting slip, surface slip, or clay body.
- mixing with slip: When adding powdered stains into slip or clay potters either add the dry powder directly to the slip, or some mix the stain dry powder with water first and then add to the liquid slip. Either way, it is recommended to let your stained slip sit for 24 hours or more. This helps it to absorb into the slip and reduce speckling. Sieving through a 120# sieve is also helpful.
- mixing into a clay body: There are different ways of doing this, and it depends on your personal preference.
- Some potters prefer to mix powdered stain into powdered clay, then wet the coloured clay and reclaim it on a plaster bat and then wedge, wedge, wedge.
- Some prefer to mix powdered stain with some hot water, then mix that into wet reclaimed clay and dry the coloured reclaim on a plaster bat and then wedge, wedge, wedge.
- Some prefer to wedge powdered stain directly into their clay body, and if choosing this option it’s recommended that you use gloves. A good technique is to cut the clay into several slabs, sprinkle powdered stain on the surface of one slab and spray it with a little water, then layer another slab piece on top and repeat. This will result in a layered cake effect of clay and powdered (damp) stain. The next step is, yes, wedge, wedge, wedge.
In any of these cases, when using stains in your slip or clay body it’s best to give it a day or two to slake into your clay to increase the chances of even colouring and avoid speckles. Be sure to stir/wedge thoroughly!
Start with testing a small amount, such as 3-4%, and increase the amount of stain based on the intensity of colour you wish to achieve. Again, it is recommended to NOT exceed 10-15% of stain content.
3. Stains used as a wash
Potters sometimes use stains as a wash, either under or over their glazes. If applying stain as a wash onto greenware, it’s also a good idea to add some flux (either frit or gerstley borate) or a body slip, in order to help the stain adhere to the surface. Otherwise after drying the stain might become powdery and could smudge.
Any tips I should know?
There are a few general tips and guidelines to keep in mind when working with stains.
- experimentation is a critical part of the process. Be sure to test, test, test, as results can vary depending on stain concentration, clay body, glaze ingredients, firing temperature and kiln atmosphere.
- a little goes a long way – you’ll start to see colour from as little as 2%, and generally recommended not going beyond 10% as there is a risk that a higher concentration of stain could cause issues with glaze and clay.
- be sure to read the guidelines produced by commercial stain companies, as it will include information about recommended maximum firing temperature, what oxides are included in each stain colour, and whether zinc should be avoided.