Ceramic frit paint is a great way to create a wide color palette for single-fired wall cladding. It also offers a high level of consistency, batch to batch color matching and a reduced warehousing requirement.
By using frits sourced from different oxide percentages a glaze can easily be adjusted to improve a variety of glaze properties such as firing range, flow, viscosity and resistance to leaching. This is a very powerful technique to have in your tool box.
What Are Ceramic Frits?
Ceramic frits are a mixture of different oxides, silicates and carbonates melted together and quenched in water, which is ground to a fine powder. They are indispensable components in most industrial glazes and enamels which mature at temperatures below the melting point of glass, and can be used to impart a wide range of characteristics to a glazing including color, opacity, texture, thermal expansion and surface smoothness.
This ceramic supply are also useful in improving glaze consistency and preventing problems such as crazing, slumping, and pinholes. They can provide the chemistry needed for specific glazes and are available in a variety of different formulations, and are very easy to use.
Because they are man-made, frits have a chemistry that is more controllable than raw materials, which can be prone to crystal growth, decomposition and other uncontrolled reactions. They are a cost effective way to improve glazes by adjusting slurry chemistry and adding new glazes and colorants.
Ceramic frits are used to prepare low temperature firing colors and glazes as well as being a cost effective way to decorate large glass panels for wall cladding, spandrel glazing and more. They offer an expansive color palette, batch consistency and a low volatile organic compound (VOC) level. They are an excellent alternative to paints and are used in conjunction with digital printing technology, allowing for the creation of a wide variety of patterns and designs.
Why Are Frits Used?
Frits are used because they allow us to make glaze effects on a large scale that would be very difficult with raw materials. In addition, frit chemistry can be very consistent from batch to batch. This is important because some of the chemistry of a glaze depends on how it behaves in the kiln, not just the chemical makeup of its components. When a glaze behaves inconsistently, it can be difficult to understand its characteristics and to suggest adjustments, improvements or fixes.
As an example, a raw material like feldspar may start to melt at a very low temperature in a glaze, and this can cause problems because it cannot supply fluxing oxides as early as other materials that melt much earlier (like soda frit). A ceramic glass frit however, will melt at much lower temperatures and can easily supply the oxides needed in a glaze at an appropriate time.
Another benefit of ceramic frits, is their ability to be blended to produce a wide variety of oxide mixtures. This gives a tremendous amount of control over opacity. For example, zircon can be added to a frit during its manufacture to make a high-opacity glaze. This is important because many glazes need to be opacified and having different opacifiers available allows one to use the best mix of oxides for the job at hand
How Are Frits Made?
Frits are a major component of glazes and enamels that are compounded from raw materials. They are pre-mixed, melted and then cooled by quenching in water to become solid. Then they are granulated to form a fine powder.
They are a critical ingredient for a wide range of glaze and glass applications including interior architectural glazing, insulating glass units, storefronts, wall claddings, skylights and glass railings. These color-rendering technologies allow architects to create glass facades and storefronts that express their creative vision by infusing vibrant, opaque colors into building edifices.
When a frit is added to a glaze slurry it encapsulates the otherwise water-soluble flux elements, alumina and, in some cases, boron. Because of this, a glaze slurry containing a frit will not easily dissolve.
Unlike raw materials that melt suddenly, frits have been pre-melted so they soften over a wide range of temperatures. This allows for easy remelting in production situations where consistency and ease of use are essential.
For example, the chemistry of a feldspar-based frit is very consistent and can be remelted over and over again. This makes it a great choice for making glazes that require a very stable chemistry. Oftentimes, frit chemistry is used to replace raw materials that are expensive, difficult to source in small quantities or have poor stoichiometry (causing glaze bubbles and defects). In addition, there are frits with unique properties such as low expansion that can be very helpful for crazing glazes.
How Are Frits Used in Glazes and Enamels
The ceramic frits we use are a combination of oxides, silicates, carbonates and boron compounds that are fired as a molten mix in a special glass furnace and then quenched rapidly with water. This process turns the raw materials into glassy, insoluble shards that are then ground up and used as glaze ingredients.
Most frit manufacturers have a range of specialized products that they spend significant R&D resources developing. They are marketed as a solution to specific problems and for producing certain kinds of glaze properties. This can include higher gloss, resistance to devritification (crystallization of the glaze), coloration, etc. Unfortunately, the chemistry of these specialized frits is often kept secret to prevent competitors from copying their formulations.
This can make it difficult for potters to understand the chemistry of the products that they are using and therefore difficult to create matching recipes. The absence of frit chemistry information also makes it more difficult to use ceramic calculations to manipulate glazes, and to target or maintain a stoichiometric chemistry.
Traditional frits for decorative and sealing applications belonged to the PbO-B2O3-SiO2 family of glasses. While these types of glasses are still produced today, they are less in demand than previously because of health and safety concerns. Lead-free alternatives have been developed for these uses, characterized by wide and forgiving firing temperatures and high durability under specific conditions.