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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.

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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

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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

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What is a porcelain enamel coating?

Porcelain enamel (also called vitreous enamel or glass-lining) is an engineered boro-silicate glass layer, which may be applied in a liquid or powder form and fused on a metal substrates, like mild steel, cast iron, stainless steel, aluminum or copper.

Unique properties

This inorganic porcelain enamel coating was already used by the Egyptians for art and jewels around 1000 B.C. and may be characterized by a number of unique chemical and mechanical properties, like :

  • Color stability (during many years)
  • Corrosion resistance (even against boiling water !)
  • Easy-to-clean
  • High temperature resistance
  • Scratch resistance
  • Typical applications
  • Enamel on mild steel (Also called ceramic steel or glass on steel) has been adopted by many different industries all over the world.It is nowadays used for providing a functional and/or decorative porcelain enamel coating to a wide range of products.This article comes from dtc-bv edit released
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The Purpose of the Black Frit and Spots on Windshield

At some point while driving or examining your vehicle, you may have noticed a somewhat curious pattern along the edge of the windshield consisting of black dots, and commented to yourself, “I wonder what those are for.” The answer to this mystery is rather simple.

The modern windshield is a marvel of engineering, and dare we say one of the most underappreciated components of a vehicle. Part of that engineering involved how the windshield is bonded to the frame. You may have also noticed the black band along the periphery of the windshield, this is called the black frit.

The black frit is a black enamel band that is literally baked into the edges of the windshield glass, accompanied by the border of black dots you are wondering about. The purpose of the black frit is to provide an etched surface that allows adhesive to bond to the glass. When a manufacturer installs a new windshield, or an auto glass specialist like DeDona Auto Glass replaces your windshield, the glass is bonded to the vehicle with the black frit as the contact point between the glass and the frame.

There is a dual purpose here, though. While the inward facing side of the black frit allows adhesive to bond to the glass, the outward facing side of the black frit acts as a shield against UV radiation in order to protect the adhesive bond, which would otherwise be weakened by continual exposure to direct sunlight.

Cosmetically, the black frit also nicely conceals the adhesive used to install the windshield and provides a more “polished” appearance. The dissolving/shrinking effect of the black dots provides a more visually appealing transition from the black border of the black frit to the transparent glass, and also provides a small amount of heat dissipation. The dots do provide some level of sun shade as well.

This article comes from dedona edit released

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Green Chrome Oxide Compound for sharpening

This is a blend of green chrome oxide compound and aluminum oxide which cuts faster and polishes more smoothly than traditional red rouge.

Green chrome oxide compound rouge will buff steel, brass, chrome & stainless steel to a mirror shine, and will bring Lexan® Sheets back to clarity. It’s ideal for polishing plane irons & soles, chisel backs, hardware and anything else that needs smoothing & polishing.

Charges and adheres well to leather, wood and felt strops. The average size of the scratch pattern measures .5 microns. Six ounce bar.

This article comes from highland edit released

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The Color Cobalt Blue Pigments Through The Ages

Although smalt, a pigment made from cobalt blue glass has been known at least since the Middle Ages, the color cobalt blue established in the nineteenth century was a greatly improved one.

The isolation of the blue color of smalt was discovered in the first half of the eighteenth century by the Swedish chemist Brandt. In 1777, Gahn and Wenzel found cobalt aluminate during research on cobalt compounds. Their discovery was made during experimentation with a soldering blowpipe. The color was not manufactured commercially until late in 1803 or 1804.

The Minister of the French government, Chaptal, appointed Louis Jaques Thénard and Mérimée to look into the improvement of artists’ colors. Thenard developed this new cobalt blue by his observations at the Sevres porcelain factory. He experimented with roasting cobalt arsenate and cobalt phosphate with alumina in a furnace. He published his results in late 1803-4 in the Journal des mines, “Sur les couleurs, suives d’un procédé pour préparer une couleur bleue aussi belle que l’outremer.”

Thénard tried the blue in oil and gum media and by the time his report was published, the color had not changed after a two-month exposure test. Production began in France in 1807. Most sources cited regard Thenard as the inventor of the blue. However, Leithner of Vienna is also mentioned as one who developed cobalt arsenate as early as 1775.

Cobalt blue was generally regarded as durable in the nineteenth century. It requires one hundred percent of oil to grind it as an oil paint otherwise its cool tone can turn greenish due to the yellowing of linseed oil. To avoid the yellowing, Laurie suggested that it be used as a glaze color or mixing it with white. It is totally stable in watercolor and fresco techniques. Field called it a “modern, improved blue”. John J. Varley, author of List of Colours, recommended it as a good substitution for ultramarine blue for painting skies.

This article comes from webexhibits edit released

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Porcelain Powder in the 21st Century

With the invention of powder coating about 60 years ago, a lot of work began in the coatings and finishing industries to leverage this new technology. The porcelain enamel industry was an early adopter of electrostatic powder coating, but a lot of development was required from both the material and equipment aspects. By the 1980s, porcelain powder coating was taking place in many factories, primarily for flatware but also in several lines for cavities, like ovens and dishwashers.

The physics of powder coating of porcelain powder is the same as for traditional powder paint, although there are some differences in behavior, etc. One of the most noticeable is the transfer efficiency; porcelain powder is about 40 percent efficient, so much more powder travels through the recovery system in comparison with traditional powder paint. Additionally, porcelain powders are often applied in a thicker film; usually six to eight mils. Almost all of the electrostatic dry powder porcelain enamel application is for major appliances; for exterior parts it is usually a two coat/one fire process, and for interior (non-appearance) parts it is a one coat/one fire process. In two coat/one fire processing, the first coat is a special ground coat enamel (designed to adhere to the steel) which is applied to a thickness of one to two mils, directly followed in a second application booth with a cover coat (for the final color of the part) at a thickness of five to seven mils. Both layers are melted/cured at about 1500 degrees Fahrenheit in a single pass through the furnace. Firing times are typically dependent on the thickness of the metal; for successful enamel coatings the time at peak temperature is two to three minutes.

For electrostatic powder enameling, the benefits are similar to powder paint systems. They include full recovery of overspray, coating thickness control, film uniformity, better edge coverage, gloss, and smoothness of finish after firing, plus the advantages of the automation and control of today’s powder application systems. The primary limitation for electrostatic powder enameling is the choice of colors; this is because the color must be smelted into the frit. The use of frit plus pigment is problematic due to differences in particle size, density, and electrical charging parameters – thus, recycling is difficult since the various constituents apply at different rates. Color change requires either multiple booths or significant clean-up time.

We have seen recent growth in the combination of robotics with powder application, which is improving production repeatability and efficiencies as well as reducing costs. R&D on electrostatic powder enamel chemical formulations and grinding technologies is also continuing with the objectives of improving application parameters and reducing defects.

This article comes from PCT edit released

 

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Deep Sky Blue Transparent Frit

We offer frits, glazes, colours and raw materials for use in the various fields of ceramics like traditional ceramics, decorative tiles, enamelware and abrasive wheels.

Transparent frits are mainly used to formulate transparent glazes, crackle glazes and different colored glazes as required. These can also be used for making partially fritted glazes for 1150C – 1180C firing temperatures.

Transparent Frit Types :
Alkaline
Alkali Borosilicate
Borax
Calcium Borosilicate

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Direct on Enamel Frit

Enamel frits are the basic ingredient of porcelain enamel. Frit is most commonly a borosilicate glass and is formulated to incorporate desired properties like chemical resistance, heat resistance, color, cleanability, and more.

Enamel frit is made by melting raw materials together at about 2400°F (1315°C). The molten glass is quenched to provide flake particles that are used to make porcelain enamel coating.

This article comes from centerfrit edit released