At The Factory: Tile Glazing
Glazing a tile transforms it from a parched piece of earth to a durable, brilliant, waterproof finished product. If clay tiles are the bones of our business then the fascinating alchemy of glaze is our lifeblood.
A glaze is made up of silica (the main glass former), metal oxides that act as a flux (control the melting point of the glass), colorants and opacifiers that make each glaze unique. A glaze can be transparent or opaque, matte or glossy, complex or sheer. Sounds simple enough, but add a trip through a kiln firing to 2010 degrees farenheit and results can vary dramatically because of several variables, including location (altitude and pressure), fuel-type ( electric or gas) condition of the kiln, and differences in raw materials.
Glaze making is not for the weak of heart, each and every glaze chemist must thrill to the accidents, celebrate and even try to replicate the randomness that is inevitable when you are playing metals, fire, and oxygen, and our team is the best!
Like working in the kitchen, we start with the raw materials, carefully weighing, mixing, sifting, adding ingredients until the glaze is well blended and the desirable consistency.
The right visocsity is key, and depends on the glaze method we are employing for the specific order.
We are committed to efficient ways of collecting and re-using that wastewater, so our wastewater reclamation system is a critical component of our glazing system. Our glaze sprayer produces wastewater that has over sprayed glaze in it.
Here is how it works. The wastewater is pumped from our collection trench into the tank pictured. After a day or so, the solids from the glaze separate from the water and settle to the bottom of the tank. The "clean" water is then pumped out of the top of the tank and used to clean the automatic glazing machine, which sometimes happens twice a day. The used glaze that has settled to the bottom of the tank is then drained out and mixed into our clay mixes for future tile orders!
Some glazes head for automated application along the conveyor belt.
Others are hand sprayed as they travel down the line.
Still others are sprayed on a stationary pallet.
Once glazed the tiles are lined up and moved to the various kiln staging areas.
Some tiles travel through our roller hearth kiln, it takes around three hours from the start, warming up, to the middle, hitting the high temperature, to finish, when they are cool enough to handle, quality control, and move on to the shipping department.
Even after years of daily production, the thrill of sending tiles into the fire is palpable.
Others glazes are slated for the new gas kilns, the firing schedule is much longer, around twenty-four hours from start to finish. The slower cooling time allows crystals to form creating our satin, matte, and specialty glazes.
Above, our beautiful new kiln that has traveled from the Netherlands to make Fireclay Tile it's new home.
Want to learn more about how we make tile? Check out the first steps in the process.