Glass, ceramics and glaze

Cloudiness in glass can come from undissolved batch material, contamination in a raw material, incorrect batch proportions, or a melting temperature or time that is too low. Check the analysis and particle size of each raw material against its specification, alongside the melting conditions.

Comparing each incoming raw material’s certificate of analysis with your specification is a good first step, because a change in one supplier’s lot can show up in the glass. Taskon supplies boron compounds into glass, including Borax Anhydrous and Boric Acid.

Bubbles, called seeds or blisters, usually form when gases from the batch are not fully released during melting, from fining that is not working, moisture, or a temperature or melting time that is too low. It is a furnace and batch question for your glass technologist.

Raw material moisture and consistency can contribute, so check incoming lots against their certificates of analysis. This page does not advise on fining agents or furnace settings.

A green tint in glass is most commonly caused by iron in the raw materials, particularly in the sand. Checking the iron content in each incoming raw material against your specification is usually the first step.

Your glass technologist can identify which material brings in the iron and how the batch should be adjusted. Ask each supplier for a certificate of analysis that reports iron content.

Glaze that does not adhere is often caused by a dusty or oily surface, a body that is too dense or too wet, a glaze applied too thickly, or a mismatch between glaze and body. It is best investigated by your glaze technologist on a test tile.

Changes in raw material lots can also affect glaze behaviour, so check incoming materials against their certificates. Taskon supplies raw materials into ceramics, including its boron compounds. See the glass and ceramics industry page.

Fine cracks in a fired glaze, called crazing, usually come from the glaze shrinking more than the body on cooling, which is a formulation fit problem rather than one faulty raw material. Your glaze technologist can adjust the recipe to bring the two into fit.

Some glaze components change how a glaze expands and contracts. Taskon’s boron compounds are listed in boron sources compared. Any change should be trialled at small scale first.

Turquoise and blue glaze colours from copper depend on the glaze base, the amount of colourant, the firing temperature and whether the kiln atmosphere is oxidising or reducing. A change in any of these shifts the colour. Test tiles varying one factor at a time will show which.

Copper compounds are common glaze colourants. Taskon makes Copper Oxide and Copper Sulphate Pentahydrate. Handle colourants as their Material Safety Data Sheets describe.

Patchy, pale colour usually comes from uneven glaze thickness, colourant not fully dispersed in the glaze, or a firing temperature or atmosphere different from the one the recipe was set for. Check mixing and application before changing the recipe.

If the colour changed when a raw material lot changed, compare the new lot’s certificate of analysis with the old one. Your glaze technologist can adjust the recipe.

Batch to batch colour variation is often caused by kiln position and firing differences or by variation in raw material lots. Log which lot went into each batch and where it fired; if variation follows the lot, check the certificates of analysis.

Asking suppliers for a certificate of analysis for every lot makes this traceable. See what a certificate of analysis should show.

A glaze technologist or ceramic engineer should set the raw material specifications for your formulation. Once you have them, Taskon’s technical team can confirm, parameter by parameter, whether its products meet them.

Send the specification with the enquiry.

The amount of boron in a glaze is part of the glaze recipe and should be set by your glaze technologist through trials, because it changes melting, surface and fit. Taskon supplies boron compounds and can confirm their grades, but does not set glaze recipes.

See boron sources compared and Borax Anhydrous and Boric Acid.

Taskon Industries manufactures boron compounds in Ahmedabad, Gujarat, including borax anhydrous, boric acid, sodium tetraborate and di sodium octaborate tetrahydrate, packed in 50 kg HDPE bags. Send the grade, quantity and delivery location for a quote.

See the borax and boron compounds range.

Taskon Industries manufactures copper oxide, published at 97% min, and is a DGFT-registered exporter, IEC AALCT7695Q, quoting to Asian markets. Send the grade, quantity, destination port and Incoterm for a quote.

See Copper Oxide and the export overview.