Identification of enameling defects

Identifying the correct type of enamel defect is the first & perhaps most important step when troubleshooting industrial enameling processes.

Analyzing enameling defects with a digital microscoop.
Analyzing enameling defects with digital microscoop

For this purpose we have invested in a digital microscoop and associated software.

Below some images of common enameling defects.

Little copperheads inside water heater
Large copperhead inside water heater

Enamel slip properties

The consistent liquid enamel slip properties is a critical parameter at any automated wet application process.

Unfortunately enamel rheology is known to change easily under the influence of particle size, specific weight, temperature, milling additives and/or pretreatment chemicals.

Failure to maintain its properties within measurable tolerances, may result in inconsistent enamel layer thickness and eventually even enamel defects.

Do you really believe that you can “feel it” with your fingers as demonstrated on the picture below, or do you rather prefer a more precise testing method ?!

Measuring enamel slip characteristics by hand
Old fashion way

Rotational Viscometer with temperature sensor
Rotational Viscometer with temperature sensor

Fishscaling of porcelain/vitreous enamel coatings

Fishscaling

Fishscaling is an enameling defect, which is characterized by small enamel particles chipping off.

Chipping off may happen directly after firing when cooling down or sometimes even days later.

example of enamel defect called fishscaling

Effected products may usually not be repaired. Due to this reason, this defect is still one of the most described topics within the international enameling industry.
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