Cover Coat Frit
Cover coat enamel frit is coated on the surface of enamelware. By appearance, it can be classified into white frit, colored frit, transparent frit. By features, it can be Acid resistant frit, Alkali resistant frit, Abrasion resistant frit, Microcrystal frit, optical luminescent frit. High temperature resistant enamel frit and insulative frit etc…
White frit can make cover coat in a white color with strong covering power. By the opacifiers used in cover coat frit, it can be classified into Titanium cover coat and Antimony cover coat. In Titanium cover coat, when Titanium dioxide is fired, it can make the surface in super white color, And its enamel layer is thin, so it can save material. It’s most widely applied in daily enamel cookware. The opacification of Antimony oxide in Antimony cover coat is not good as Titanium Dioxide, so its enamel layer is thicker. It’s usually used in cast iron bathtub or other enamelware not for food containers.
(Antimony White Frit:)
②Colored cover coat frit:
It’s made by white frit with pigment. Pigment can be added when firing or milling. Colored cover coat frit has colored Titanium frit and colored Antimony frit etc…
(Titanium Ivory Frit:)
It has no opacifying power, and it’s transparent enamel frit. It’s usually coated on cover coat to enhances glossiness. And it’s also used as a basic frit to mill pigment together, which is called decal transparent frit.
④Enamel frit with chemical properties:
This type has Acid resistant and Alkali resistant frit. Acid resistant frit contains more than 65% silicon dioxide, it’s mainly used in chemical industrial enamel product. Alkali resistant frit contains much Zirconium dioxide and it also need silicon carbide and Titanium dioxide to enhance its Alkali resistance.
(Acid Resistant enamel frit for pipe:)
⑤Enamel frit with mechanical properties:
It’s Abrasion resistant frit. There are two ways to improve abrasion resistance of enamel frit. One is to add Silicon Carbide, Boron Nitride worked as milling additives. Other is to micro crystallize enamel frit to gain microcrystallization enamel frit with better abrasion resistance.
⑥Enamel frit with optical properties:
Namely, luminescent enamel frit. Enamel frit with Zinc Sulfide and Cadmium Sulfide added, mainly used in enamel signage and instrument panel etc…
⑦Enamel frit with thermal properties:
High temperature resistant enamel frit can be used in more than 750℃ temperature, can bear sudden change of temperature. It can’t contain any alkali metal oxide, and it contains much (40% or more) Boric oxide and few Beryllium oxide. It also need to add some refractory materials like Aluminum oxide and Chromic oxide. High temperature resistant enamel frit mainly applied in jet parts protection or paint for nuclear power reactor.
⑧Enamel frit with electrical properties:
It’s resistor enamel frit. It has very big electrical resistivity and it’s insulative enamel frit. It’s not allowed to contain any alkali metal oxide. It’s usually used to be wire of insulating material or insulative coating material for printed circuit board.
Enamel coating for the edge of enamelware. The expansion coefficient is higher than normal cover coat frit. And it has wide firing temperature range, elasticity also better. Edge frit has many colors, usually worked as decorations for the edge.
(Blue Edge Frit: )