Ceramic Toners and Glazes

A ceramic toner and glaze combination can be used to decorate ware such as table china, porcelain, tiles, giftware and promotional ware, earthenware objects, glass and glass ceramics and vitreous enamelled metals.

This technology is well established to screen print inks or suspensions of ceramic colours onto water-slide paper to form decals for permanent decoration of ware. These decals are applied to ware and then fired to produce a durable decoration on the surface of the ware.

Inorganic Colour

Inorganic pigments for ceramic applications are a major part of the decoration process. The particles used in inorganic pigments have to be very fine and their particle size distribution must be well defined. This is important for their optical behavior as well as for their chemical stability, which is dependent on the amount of surface that is exposed to attack by oxidation and other chemicals.

A number of different types of inorganic pigments can be used for ceramic tones and glazes, each displaying a unique set of properties that are important to the design and appearance of the final product. These properties include the size of the particles, the particle distribution, their chemical stability, and the ability to withstand chemical attacks.

For example, some of the inorganic pigments used in ceramic tones and glazes include colloidal metallic gold, silver chloride, and cobalt oxide. These pigments produce a variety of colors depending on their ratio of metals to the base. The most popular color is pink, which is achieved by using tin-gold (or selenium). Additions of other metals, such as chromite or copper, can also be used to achieve different shades and tones.

Another type of inorganic pigment is a glass frit, which can be used for creating ceramic color prints on glass plates. In this case, the glass frit and the fine inorganic pigment particles are mixed to form a paste, and the paste is printed on the glass plate by screen printing. Then, the paste is heated to decompose the resin content and fix the glass frit to the glass plate, resulting in a ceramic color print.

The particles used in the ceramic toners are a mixture of fine inorganic pigments and a heat decomposable binder resin having an acid value of at least 5. The fine inorganic pigments are kneaded and heated at a temperature of 150 to 200 deg C to prepare pellets, and then pulverized.

The powder generated from the pulverizing and classification process contains a very high specific weight of the toner. This can cause several problems when using it for electro printing, including the problem of particle agglomeration and the difficulty in obtaining a narrow particle size distribution. In order to avoid these problems, the particles were treated with a nanometric silica additive. This additive increases the flowability of the toner particles and prevents the agglomeration of the inorganic pigment particles.

Organic Polymer

Organic polymers are a versatile material that can be used in a wide range of applications. They are also suitable for use in ceramics, as they can be easily incorporated into glazes or tones.

Toners containing an organic component are often produced using traditional manufacturing methods, such as melt blending, extrusion and chipping, particle formation and crushing ceramic tile and mosaic pigment or solution polymerisation. However, these processes require a polymer that is able to maintain good melt flow characteristics and have a glass transition temperature (Tg) above 30deg C. In addition, the component must be able to produce large particles of toner that can be used in milling or aqueous printing.

Alternatively, toner can be made by flocculating a liquid suspension of an organic polymeric material and particles of an inorganic ceramic colour. In this case, the polymeric material is selected from olefin polymers such as polyethylene or polypropylene, diene polymers such as polybutadiene, polyisobutylene or polychloroprene, vinyl or vinylidene polymers such as polystyrene, styrene butyl-methacrylate copolymers, acrylonitrile-butadiene styrene terpolymers and polyvinyl butyral, polyvinylethers or polyvinyl ketones, fluorocarbon polymers such as polytetrafluoroethylene and polyvinylidene fluoride, heterochain thermoplastics such as polyamides, polyesters, polyethanes, polypeptides, casein, polyglycols, polysulphides and polycarbonates, and cellulosic copolymers such as regenerated cellulose.

The inorganic ceramic colour may consist of a ceramic pigment or of glass frit. The inorganic pigment may be dissolved in the polymer or the polymer may be dissolved in the inorganic colour. Inorganic pigments are usually of particle size 0.1 to 20 mm, but larger or smaller particles may be used.

As ceramic tones and glazes are typically dehydrated, dried or slurry-dehydrated products, it is important that the organic polymer has sufficient hygroscopicity to permit dehydration and drying. This is particularly true for the olefin and diene polymers, which may need to be heated at high temperatures in order to be able to undergo the drying process.

In a further step, a predetermined amount of water is added to the ceramic glaze solid material, so as to obtain a slurry concentration. This slurry concentration is then adjusted by mixing / stirring, and a ceramic glaze is then prepared from the slurry.

Particle Size

The particle size in ceramic toners and glazes is a key factor that influences their properties. This can be related to solubility, surface area and deflocculation. The best way to measure this is with a sieve. The most common sieve used is the Tyler sieve (also called a square screen) which has an opening of 56mm and a mesh of 0.1 mm.

A typical glaze slurry will contain a mix of particles in the range 1 to 50mm, preferably between 10 and 30mm. In general the larger the mesh size the more soluble a material is. This is because the particles have more surface area to absorb water and bind with other particles. It’s also easier to get the slurry to settle out and hard pan when you use a finer mesh.

Another thing to consider is the size of the glass frit. It should be large enough to prevent melting of the pigment particles and adhesion of the ceramic color print to the plate before sintering. This can be achieved if the glass frit has an average particle size of from 0.5 to 3 mm, and if the glass transition temperature Tg is at least 350deg C.

Depending on the type of toner and the type of ceramic it’s applied to, there will be different sizes and shapes of particles. For example, a toner that is applied to a red ceramic will have a higher particle size than one that is used on a white ceramic.

A lot of different materials can be used as toners in ceramics. These can include ceramic pigments, metal powders or flakes and any other type of iridescent, fluorescent or micaceous-type particles.

This can help to improve the color and/or surface appearance of the slurry or glaze. This can be done either by using a wet or dry process.

For example, a nepheline syenite can be ground down to 270 or 400 mesh to improve its solubility and help it to deflocculate more quickly in the glaze melt. This can also help to reduce the amount of sintering required to make the glaze.

Flow Additives

Ceramic toners and glazes can be tricky to work with. Sometimes they perform well when dipping or pouring, but dry so quickly when brushing that it’s nearly impossible to get an even coat. This is ceramic tile and mosaic pigment where a few flow additives can help to remedy these problems.

Flow additives are a category of flow control materials that can be added to a glaze before it is fired or used in conjunction with glazes to improve performance in different firing conditions and applications. These additives can help with a variety of different issues including adhesion, suspension, dry hardness, rheology, and surface leveling.

CMC gum is a common gluing agent that can be used to slow drying times and improve adhesion and dry hardness of a glaze. It also helps to smooth out and soften a hard glaze. It can be diluted with water or with other mediums to achieve different effects, depending on the level of translucency and sheen desired.

Another useful additive is borax. This flux can reduce the melting temperature of a glaze, making it more compatible for lower temperatures and less likely to burn out in high fire. Other fluxes include nepheline syenite, sodium carbonate (also known as soda ash), and boron.

Many of these fluxes can be added to a glaze batch before it is fired or can be used in conjunction with a ceramic slip, stain, or underglaze to achieve a particular color or tone. They can produce a range of colors, from delicate turquoise to rich red, yellow, green, pink, and blue.

Some of these fluxes can be quite toxic, as they contain radioactive elements, so care should be taken when handling them or using them in your work. Some of the most common colorants are gold, ilmenite, iron chromate, silver and bismuth oxides.

Other popular materials include copper oxide, manganese dioxide, rutile and titanium dioxide. These opacifiers can be mixed into a glaze batch before it is fired or added to a ceramic slip, stain, or luster overglaze to achieve a certain color.

These flow additives are a very important part of the process of creating a good ceramic glaze. They can be used to prevent a glaze from drying too fast when brushing or to ensure a better bond between the raw glaze and bisque ware. They can also be added to glazes to make them more opaque.