Glazing pottery is a great way to protect them from water or wear and tear. It involves adding a layer of glaze to the surface of your pottery and then fusing them by placing the pottery in a high-temperature kiln. But the bottom of pottery cannot be glazed in the same way, as the hot liquid glaze will fuse to the kiln shelf.
So, how do you glaze the bottom of pottery? There are a few different ways you can do this. You could leave the rim unglazed, and place the pot upside down in the kiln. You could also use a technique called wadding, which involves temporarily adding to the bottom of the pot. Alternatively, you could also simply use ceramic stilts.
In this article, we will discuss each of these techniques in detail. By the end, you will know which technique will suit you the best.
The first and one of the easiest ways to glaze the bottom of pottery is to leave the rim (the outer edges of the pot) unglazed. Apply wax resist to the rim and glaze. You can then place the pot with the unglazed rim upside down in the kiln for firing.
The rim, being unglazed, will not fuse with the kiln shelf. And this will instead allow the rest of the surfaces to fuse well with the glaze, including the bottom of the pottery. Sometimes, the glazed ceramic can drip and stick to the shelf of the kiln. So, it is always a safe bet to have some sort of protective layer, like Kiln Wash or a Cookie. It’s best to apply wax resist on the rim to ensure no glaze sticks to the rim after glazing.
You must be aware that leaving the rim unglazed will prevent it from getting the same smooth texture as the rest of the glazed pottery. But you can always apply various decorative covers over the unglazed rim.
For example, some ancient pottery made in China has had some sort of metal (silver, gold, brass, or some alloy) covering the unglazed rim of the pot. These metal covers were creative ways to cover the last unglazed surface of the pottery.
So, one of the simplest and the most popular ways to glaze the bottom of pottery is to leave the rim unglazed and then fire the pot upside down.
But suppose you want every part of the pot to get glazed, including both the rim and the bottom of your pottery. Wadding is a great technique that can help you achieve this.
Wadding is the process of symmetrically putting some sort of material, usually balls of clay, at three or more different points at the bottom of the pot once the glazing material has been applied. The balls are placed in such a manner that the balance of the pot is maintained and that it can still be placed upright inside the kiln while firing.
What this does is allow the heat during the firing to reach every surface of the pot, including the bottom. Since the wadding will lift the bottom slightly over the shelf of the kiln, the glazing material at the bottom of the pot cannot fuse with the kiln. Hence, the objective of glazing the bottom gets achieved. It’s best to place the wadding on a cookie to protect your kiln shelf from any glaze that may drip while firing.
There are several different forms of wadding. These include the likes of clay wadding, calcium wadding, and alumina wadding. Some of these have to be removed or broken off once the firing is over, while others will crumble or fall off on their own.
This process will leave dots at the points where the wadding was placed since the fire and heat from the kiln will not reach them. But these can always be covered decoratively.
The third and final method we will be looking at involves the use of ceramic stilts. This requires you to get some extra furniture for your kiln. But once you have these ceramic stilts, this is perhaps the easiest way to glaze the bottom of pottery.
In some ways, this method seems related to the previous method of wadding. The bottom of the pot is placed on the pins of the stilts instead of the shelf of the kiln. This will help the bottom of the pot avoid contact with the shelf of the kiln during the firing process. A cookie is also recommended because the glaze may drip off the bottom during firing.
Like with wadding, this will leave a mark at the points where the pins held on to the pot. But this can always be corrected by grinding the marks.
Should You Leave the Bottom of Pottery Unglazed?
While the desire to have some of your pottery glazed on the bottom. For instance, if you are making a ceramic pipe, spoon, or hanging planter. There are some arguments against this.
The first argument, of course, is very much related to this article. If you’re planning on leaving the bottom of your pottery unglazed, it can be placed in a kiln for firing without much problem. All the solutions we have discussed so far have assumed the glazing of the bottom.
The second argument has to do with friction. Glazing will make the bottom of a pot smoother, and hence more slippery. This makes it much easier for the pot to slip or slide, and hence, much easier to break.
There are, of course, plenty of reasons to want a glazed bottom for your pottery. We just wanted to make sure you got all the information from both sides.
More Glazing Tips
It seems suitable at this point to share some general tips on glazing pottery. If you’re a beginner, some of these tips could be extremely valuable:
- Mixing the glazing liquid well is very important. You should use an electric mixer and then apply the glaze immediately as the ingredients tend to separate after a while.
- Having a good brush can go a long way. Make sure you use a brush that can hold a lot of glaze so that it can be applied more evenly.
- When applying multiple coats of glaze, change the direction of your brush strokes for each coat. This will help prevent the formation of steak marks and will leave you with an evenly distributed coat of glaze.
- Always glaze the insides of your pottery before you glaze the outer surface. You will have to glaze the insides and the outside separately. So, if you glaze the outside first, you will risk leaving marks and spots while handling the pot again when you’re glazing the insides.
- Keep the pot clean right after bisque firing. At this point, any dirt or oil from your hand or something else could resist the glaze, eventually leaving a bare spot at the point of contact.
- When applying multiple coats of glaze, let the previous coat dry before you apply another coat.
- Sandpaper can be a handy tool for smoothing out rough or uneven surfaces.
Glazing the bottom of pottery will give it a nice and even surface. But there is a bit of a challenge to this, as the liquid glaze will easily fuse with the shelf of the kiln.
We discussed three methods to prevent this. The first method involved leaving the rim of the pot unglazed and then firing it upside down. The second method we looked at was wadding. The third method involved the use of ceramic stilts. While each of these methods can definitely help you glaze the bottom of your pottery, there are advantages to an unglazed bottom worth considering.
- Community.ceramicartsdaily.org: Glazing The Bottom Of My Pottery
- Quora.com: In pottery, how do you glaze the bottom of a vase?