urability of vitreous enamel coatings and their resistance to abrasion, chemicals, and corrosion

Despite all the positive aspects previously underlined, some issues limit the application of this type of vitreous enamel coating in many industrial fields. Vitreous enamel shows nonexcellent abrasion resistance, despite its superficial hardness, and this is mainly due to its brittle behavior.36,37 Abrasion is a very common mechanism of degradation of enameled surface, as fracture may occur and propagate,36 leading to loss of aesthetical properties, disclosure of the intrinsic enamel porosity, and loss of mass through the formation of flakes. Degradation due to abrasion negatively affects corrosion protection properties, as cracks can reach the metal substrate and allow a direct contact between the substrate and the aggressive environment.

This review focuses on the durability and degradation of vitreous enamel coatings, taking into consideration the external agents that can cause a relevant loss of their protective properties. Each section will consider a different property that makes vitreous enamel a coating of industrial interest, focusing on abrasion resistance, resistance to chemicals and detergents, and resistance to corrosion. The work highlights how these properties can be improved and examines the main scientific studies published in this regard. The review makes a critical analysis of the methods that are currently used to characterize these properties, highlighting their positive aspects and limitations as well. In conclusion, a discussion about the future perspectives of scientific research on vitreous enamel coatings will be introduced, showing possible research paths to be followed.

Enamel properties affecting durability

Vitreous enamel represents a particular type of vitreous enamel coating as it is made from low-cost materials, but at the same time it entails interesting technological properties. The degradation and durability of this vitreous enamel coating are key aspects to be taken into consideration when thinking about industrial applications. It is then necessary to investigate the external agents influencing the loss of properties of these vitreous enamel coatings and to study possible ways to improve their resistance and durability.

This article comes from springer edit released

Pigment: Cobalt Blue, the 19th century sky

Blue is not just a primary colour, but the colour of the unclouded sky, of many bodies of water, and by convention of the Virgin Mary’s clothing. Blues occur in nature in a wide range of chromatic intensity, so having a reliable lightfast deep blue is one of the first requirements for any palette.

Blues are also among the most fascinating pigments in terms of their history and use. Ultramarine Blue is one of the oldest pigments still used in painting, and its history could fill a book. Over a similar period, artists also used Smalt, made from powdered blue-coloured glass, in which the active pigment is cobalt oxide. Thénard discovered cobalt aluminate in 1803-04, and recognised its potential as a pigment. As this preceded the introduction of artificial Ultramarine, cobalt blue material was quickly introduced into artists’ paints, becoming available in oil paints and watercolours from around 1806-08.

So far, I believe that the earliest recorded use of cobalt blue material is in the sky of JMW Turner’s oil sketch of Goring Mill and Church, thought to have been painted in 1806-07. This shows how similarly Turner started his oil and watercolour paintings. Once brought to this state, Turner could return to the sketch later and add foreground detail before completing it.

In this sampler of modern oil paints made by Williamsburg, each is shown straight from the tube, and below in approximately equal mixture with Titanium White. The pigments are, from the left: Cerulean Blue (genuine), Cobalt Teal, Cobalt Turquoise Bluish, cobalt blue material, Ultramarine Blue (synthetic), Indanthrone Blue, and Phthalo Blue.

Cobalt blue material is an excellent and lightfast pigment which is not as deep blue as Ultramarine, thus has lower tinting strength, and is semi-opaque. It remains popular today, but has always been expensive. Once Ultramarine was being manufactured commercially after 1826, synthetic Ultramarine Blue quickly became considerably cheaper than cobalt blue material.

Cerulean Blue had actually been discovered before cobalt blue material, but was not introduced as an artists’ pigment until the middle of the nineteenth century, after both cobalt blue material and synthetic Ultramarine. Indanthrone and Phthalo Blues are modern organic pigments which became available after 1900.

This article comes from eclecticlight edit released

Glass Painting – Enamel Powder for Copper

ENAMEL SUPPLEMENTS – For Medium Temperature Enamels for Copper, Gold, Silver, Low Carbon Steel, Window Glass, Stained Glass, Bulls-eye and Spectrum Glass, Effetre (Moretti), 400 Series Stainless Steel and Pottery (A.K.A. Ceramics)

Glass Painting – Enamel Powder

A series of vitreous enamel powders which fuse slightly below 1200ºF. Mix with your favorite painting medium.

The glass painting enamel powders will attach to glass at 1250 degrees F. They will gloss between 1300 and 1400 degrees. F. They may be taken up to 1450 degrees F. without loss of color. Firing times and temperatures are only guides. Your actual experience may indicate the firing may need to be more or less time and temperature.

You may want to vent your kiln as it heats up to allow for any painting medium fumes to escape kiln.

This article comes from thompsonenamel edit released