What is a frit?

Frit (or frits) is a substance, which results from a number of chemical reactions that involve (and fully transform) a mixture of raw materials. Those raw materials are typically metallic oxides. The chemical reactions involved take place during the melting of the mixture at temperatures well above the 1000 °C and the subsequent quenching of the melt; this leads to the immobilization of metal elements in the resulting glassy flakes or granules. During the chemical reaction, the atomic bonds of the raw materials are broken and their elements (metal atoms and oxygen atoms) are completely rearranged within the amorphous structure of the newly formed substance. The main identifiers as included in the EINECS database are:

Substance name: frits, chemicals; EC #: 266-047-6; CAS #: 65997-18-4.

Is the frit a substance or a mixture?
Frit is a substance. The reason is that in the manufacturing process the raw materials are transformed into a new substance. Once the reaction is completed, they cannot be separated again as such from the frit. The physico-chemical properties of the new substance frit are a function of the network formed.
What is the production process used in frits manufacture?
Frits are obtained by fusing at high temperature, either in a continuous or discontinuous process, a mixture of a wide variety of possible raw materials (generally inorganic oxides), and then rapidly quenching the molten mass. Quenching can be done in water, or by means of cooling rolls (with this option, air is used to facilitate the quenching), resulting in flakes. Afterwards, frits can be grinded to a powder, milled with water to a slurry, or be used directly in granular form.
If the frit is a substance, why do I receive from my frit supplier a composition expressed in metal oxides?
Traditionally, the convention between frits manufacturers and downstream users was to express the composition of the frit as percentage of the oxides of the elements contained in the final substance. Indeed, X-ray Fluorescence results (the most common analytical technique used to establish compositions of frits) are expressed as the amount of oxides of each element. However this does not mean that the oxides are present as such in the frit.
Are there any metal oxides present “as such” in the frit?
No. Because of the chemical reactions that take place during the manufacturing process, a new substance frit is created, in which the elements of the raw materials are incorporated via new and strong chemical bonds that become an integral part of the frit structure.
How does the Safety Data Sheet of a frit have to be prepared?
SDS of frits should be prepared following the criteria used for any other substance.
I receive a Safety Data Shet of a frit with oxides in section 3 is this correct?
No. Frit is a substance; therefore it should not include any reference to metal oxides in section 3. In case that a company wishes to receive details of the composition of a frit, it should contact its provider of frits asking for technical specifications; however this does not have to be included in the SDS.
Why are there some frits that are classified and others are not?
The Frit Consortium, together with other national associations, has evaluated different typologies of frits. It has been demonstrated that while some frits do not pose any hazard for human health nor the environment, other frit compositions (which include hazardous elements in the raw material composition) may show levels of bioavailability of metals that could generate hazards that require certain classification under CLP Regulation.

Frits that are not classified under the above mentioned legislations are considered to be exempted from the obligations of registration under the REACH Regulation.

Why do I receive frits with a REACH registration number and others without it?

Frits are included in Annex V of the REACH Regulation as substance that can be exempt from registration. Certain conditions are necessary to demonstrate the exemption, which include the demonstration that the elements included in the network of the frit do not become bioavailable during the life-cycle of the substance. The work developed by the Frit Consortium and other national associations has demonstrated that certain frits compositions can be exempt from registration, while others have to be registered under REACH.

It has to be noted that exempted frits do not require any kind of classification or labelling.