When it comes to choosing whether or not you want to fire something single-fire or bisque fired, you’re also given the option of firing this with a low-fire too, since it works better that way. Here, we’ll go over the process of it, the advantages and disadvantages, along with some of the best single-fire low fire glaze you can use in your pottery to give it that extra look to it.
What is It?
This type of glazing essentially means you’re literally glazing this, and then throwing it through the kiln just once.
The exact process includes the following:
- Waiting till the piece is dried
- Put it in the glaze you choose
- Let the excess come off
- Throw it in the kiln
This is actually a process that potters have used for years, and it is proven to actually be really beneficial.
When we hear about glazing, we typically know about this from pottery that’s gone through a bisque firing already. This is basically two-step firing that has the following process:
- The clay gets leather hard
- It’s fired once, but not to the full temperature
- When taken out, it’s then cooled, and you put the glaze on it
- Once it’s finished, you fire it once again for the full firing process, so the glaze changes the pottery
What’s surprising, is that method was actually not discovered until much much later, and it was actually a tin oxide glaze that was used.
When choosing glazes for this, never use tin oxide in them, because it creates the following:
- Too much damage to the piece
- It doesn’t hold very well
But, if you’re learning single-fire glazing, this is a great way to do it, and we’ll even give you some glazing options later on.
The Best Methods?
When doing this type of method, there is one certain way that actually makes it work really well, and below, we’ll discuss what it is, and why it matters.
- First thing you do, is you glaze the inside of the pot when leather hard
- Then you put it outside when it’s bone-dry
- The second one is you glaze the whole piece when leather hard
Now, the former is better for those who are starting out, and that’s because you’ll be able to make more mistakes. Unfortunately, with the latter method of pottery firing and single-fire glazing, it actually doesn’t leave a lot of room for error, and it puts the piece at risk for shock during the firing stage.
The Pros and Cons
So why would you do this type of firing? What will it do for your pottery?
Well below are a few advantages that this type of pottery firing brings to the table:
- It can save you a boatload of time
- It can also save you a lot of money
- You’re basically cutting down the process since it can take a long time to get items made
- It also doesn’t try your patience as much, since you don’t need to fire it too long
- It is good for pottery that isn’t super high-firing since this can reduce the time
- You only need to fire up the kiln once, so it saves you money
- It can create some awesome effects in the glazing itself as well
- You won’t have to wait around as much for the kiln to finish your piece
Now, there are a lot of great advantages to this, but as well, there are some serious disadvantages too, especially if you’re trying to create functional ware.
Of course, though, you will have to work with these disadvantages too, and if you’re new, this can also be a bit problematic for you.
These disadvantages include the following:
- Cracking is very common with this
- You should also ensure your pottery is dry beforehand since they can explode in the kiln
- You have to very slowly increase the temperature because too quick will cause it to explode
- You also run the risk of the glaze flaking or cracking in the can
- There is also the chance that bubbles will happen
- It isn’t good for functional ware since not all of the moisture will be gone
- It’s incredibly fragile, so you’ll have to be very careful when putting the glaze on
Of course, this is a good skill for you to learn, and something worth trying out if you do love to glaze, but always keep in mind that it’s nowhere near as easy as you probably think it is, so always have that in mind when you’re thinking about doing this, and know that it definitely takes some skill.
Clear Cone Low-fire Glaze
When using this formula, you’ll notice that it can be a bit hard to fully master, but it’s a great one that’s perfect for terra cotta.
To make this, you add the following:
- Ferro Frit 3134 30%
- EP kaolin 25%
- Ferro Frit 3135 45%
- Calcium Oxide .68%
- Sodium Oxide .31%
- Boron Trioxide .85%
- Silicon Dioxide 2.70%
- Aluminum Oxide .52%
Now, you can typically get this for a lot of low-firing glazes and pottery that is single-fired. However, there are a few cautions you need to keep in mind.
- When you’re using this, you should never apply it too quickly
- You should understand that it will have a pretty decent thermal expansion
- The boron is also very high, and it can be a bit cloudy if you’re not careful
- The aluminum oxide is very glossy, and if you put too much it does run the risk of crackling and glazing
- It does have a high kaolin content, which can potentially cause crawling and cracks, so be careful
This is a good basic recipe and is perfect for low-firing glazes that are done once, just make sure you know of these small little tips to help with this.
Another fun glaze that you can use is this one. Now, as of note, it is incredibly toxic due to the lithium in this, and you should never work in an area that isn’t ventilated with this.
The parts of this include the following:
- 8% lithium carbonate
- 46.4% Ferro Frit 3269
- 13.6% silica (325 mesh)
- 21% kaolin
- 11% whiting
Typically, in order to get the best results with this one, you need to do the following:
- Mix this immediately before you apply it
- When applied, make sure it’s very even in the texture
- Fire this to max cone 06
- This can work as a single-fire, or also a multiple firing glaze, and it does produce some great results.
RCA Alkaline Glaze
This is another pretty glaze that works very well in low-firing atmospheres and for single-fired pieces. To make this, you need to mix the following together:
- 5% whiting
- 10% EPK Kaolin
- 85% Ferro Frit 3110
After that, you then add the trace amounts of this into there:
- 3% copper carbonate
- 1% bentonite
At this point, you then put it onto the pottery piece and end up firing it. There are a few things to keep in mind during the firing, and they include the following:
- This glaze is typically a bright and coppery blue-green
- Apply this thick
- Fire this on a low to medium speed
- Keep it only to cone 04
- Let it hold at the top temperature for a bit in order to really get the best results
This is a great one, and it’s relatively simple to do compared to some of the other pieces out there.
If you want a simple mate glaze, then this is a great one. It doesn’t have any special recipes or the like, but here, we’ll talk about this below.
To make it, you have to add the following:
- 7.1% lithium carbonite
- 40.5% Ferro Frit 3134
- 12.9% whiting
- 21.7% EPK kaolin
- 17.8% silica (325 mesh)
At this point, you simply mix this one together, and then you’ll have a glaze that’s matte, which is perfect for that type of pottery, especially if you want something that’s simple, and incredibly effective.
Tips for this type of firing
When firing in this way, there is a lot that you should always make sure that you do, and you’ll want to make sure that you consider these following aspects in order to make it work.
- First, you should make sure that the clay is incredibly dry before the glaze is put on
- You could leave this to bone-dry before you glaze, but leather-hard works well too since it can help you get a really nice firing aspect on it
- If you’re going to be single-firing, it’s best if you at least have a decent amount of knowledge with glazing
- You should make sure that there is a lot of clay on your pieces since you’ll need to rehydrate it
- If you notice that there isn’t enough clay in the glaze or piece, it will flake, so the solution is to add more clay pieces before you fire
- Shiny glazes can be a bit harder for some of these, but if you add more clay to it, it can work well as a single-firing pottery glaze
- Some people will use a spray glazing technique in order to minimize the water that’s absorbed
- Spraying is another good way to reduce your actual physical handling of it
- If you are going to handle this type of clay, some of the best ways to do it include having gloves that are water-resistant, so it’s not getting onto your hands, and instead keeps the water on the piece
When you’re single-firing pottery, do keep these in mind, and realize that it does take a bit of time, and some serious effort to manage to create a piece. You should also realize that the glazes can vary in texture and type, so always be willing to try a new glaze whenever you can, in order to achieve the best results possible.
Cautions with Glazing
When it comes to a lot of these glazes, there are also a few cautions that you should have in place. This doesn’t even include just the glazing process, but also the firing process too.
They include the following:
- Always wear protective clothing, gloves, and a mask and respirator, and also protect your eyes when glazing, since it does contain silica which is toxic.
- Do know your kiln and how fast it fires before you try any of this since if it fires up too fast, it risks explosions
- Know glazing and become an expert in glazing before you try this
- Always make sure you’re around when you try this type of firing, and never leave a kiln unattended
- Always practice kiln safety when you’re doing this
- Make sure that you never open the chamber of a kiln with this type of piece too fast, since it is incredibly volatile and can shatter
- Make sure that you are careful during each step of the process since if you are too rough, it can break
- Understand that this type of pottery isn’t ideal for functional ware, but works best with decorative pieces
When choosing whether or not you want to single-fire your pottery, you need to consider the glazing content of what you’re putting on there, along with the process of this as well. By understanding that, you’ll be able to create and craft a better, more rewarding piece than you have before.
For a lot of people, the right type of glaze matters with this, and understanding how to glaze will benefit you and your pottery experience in many ways, especially when single-fire glazing.