In this post I describe a technique for using absolutely every last drop of your underglaze.
After equipment for mixing and using colour underglaze have been washed you can use the resulting rinse water to make watercolour style brushwork on pottery.
Most ceramic colours, especially the bright non-earthy ones, are manufactured pigments that are made from a huge range of different mined oxides. In Aotearoa, the commercial ones are all imported, and are one of (if not the most) expensive ceramic materials that we often buy in tiny amounts at a time.
The technique you choose to colour ceramics makes a big difference to how much colouring oxides are needed. I have found that colouring the clay body for example, can use a whopping 10% colouring oxide as a proportion of total materials used to make each piece, whereas light watercolour brush work on just the surface uses a fraction if hardly any at all.
This technique takes that one step further and uses up the underglaze residue on brushes and tools that would normally be lost during washing up.
Equipment needed:
small containers
small sponges on a stick (plastic ones I use come from Daiso)
water spray bottle with adjustable fine jet
some greenware pottery to decorate
Diluted underglaze rinsed and sponged off equipment
I started using this technique as a way of using up all the wasted coloured underglaze that results after mixing and sieving underglaze ready for use. As I often use about 6-10 colours at at time, I was wasting a lot of underglaze every time as residue left on the sieve and mixing containers. I didn’t flush this down the sink, all of my rinse water is collected in a bucket but it is mixed together with all other sources of colouring oxide to make a lucky dip glaze. With this new technique, however I get a great result while keeping the colour I purchased (rather than a random blurky colour in the lucky dip glaze).
Use the water spray bottle to sluice water off equipment such as brushes, pottles and sieves into a container, using as little water as possible by adjusting the jet. Use a sponge on a stick to mop up any residue as well and add to the container. Try to clean the equipment using as little water as possible and collecting the diluted underglaze in the container. Now you have some watercolour underglaze to decorate pots and can use the sponge for dot decorations.
Use a fine jet setting on the spray bottle to remove as much underglaze from brushes as possible before washing
Sponge dot decorating using watercolour underglaze.
You may need to adjust the wetness of the underglaze and the greenware you are working with so that the watercolour underglaze will absorb into the surface adequately and not be too runny e.g. it might work better on dryer pottery or you may have to let some water in the watercolour underglaze evaporate before using.
Once finished you can add the diluted underglaze back into the main container of underglaze (leave the lid off to evaporate some of the extra water as necessary.)
As ever, test your results in the kiln before committing to a big project!
