Mixing a powder for a dipping/pouring glaze, to the right consistency, for a particular clay body is complicated. There is much to consider. If you want a simple answer, then the best we can advise is a starting ratio of 1kg powder to 600ml of water. Give it a good mix, preferably with a No Splash Glaze Mixer. Add more water little by little until it meets a single cream consistency.
But as you will begin to understand in ceramics, nothing really is that simple.
A bisque clay body will absorb water from a glaze. A different clay body, different thicknesses, and different bisque temperatures will all change that absorption rate. This then, needs to be considered with the dipping time and frequency of dips, which will all go to create variation in glaze coverage and ‘take up’. I have not even mentioned the individual properties of each glaze.
Dipping and Pouring glazes are designed to be a quicker method of glazing. A dipped pot should dry fast so you don’t get dribbles and runs. And ideally, you would be dipping efficiently getting as much on in one dip as possible. To get it perfect, you need to test.
To help this process, we have written some guidance with each of our ‘Vitraglazes’ in an attachment pdf. This is called ‘The Really Useful Dipping Guide.’ Although we have measured each to a specific gravity and given a water volume to powder equivalence, we are aware this is only half the story.
Having the right viscosity of a liquid helps. For instance, a glaze that is too runny can be gelled so it moves very little (flocculating). A thick liquid which does not flow well can be altered with more water or in some cases other suspension agents (deflocculating). In ceramics, we use ford cups to measure the viscosity. These are cups that have a hole, and when you fill it up, the glaze will run out of the hole. We time this, to when the glaze breaks in flow, this gives you an idea of its viscosity. Now depending on the powder, most notably the clay content within that makes the difference, you might want to thicken it or thin it.
It can happen that a dipping glaze dries too quickly, if you notice that the glaze is cracking shortly after the dip then it is possible that the drying needs to be slowed a little. CMC is what we normally add for a brush-on glaze, but a little of this can help slow the drying and help reduce the potential for crawling. We have further instructions with the product.
You will now appreciate there is more to a dipping/pouring glaze than simply adding water. As each powdered glaze is different with its own raw material ingredients and with the variation of the clay bodies, it is nearly impossible for us to advise precisely.
Having made your dipping mixture, don’t forget to sieve. Use a 60# mesh sieve for earthenware and an 80# mesh for stoneware.
Note: A traditional test is sometimes advised in which you can judge the consistency of your glaze by dipping your hands. However, we would avoid this as there are glazes which contain toxic materials and irritants to the skin.
Further Information
All dipping mixes should be tested for their colour, drying speed and quality of glaze fit. We advise that you do not apply your dipping glaze straight to the final ware without knowing its fired finish.
