Synthetic industrial inorganic pigments

Synthetic industrial inorganic pigments are created through chemical manufacturing rather than by grinding and washing clays or minerals taken directly from the earth. The techniques for producing these substances on an industrial scale were developed after 1800, making them the first modern synthetic pigments of importance to artists.

The amazing story of these early industrial inorganic pigments is well told in Philip Ball’s Bright Earth. Nearly all synthetic inorganic pigments were discovered or identified in the grand European flowering of inorganic chemistry that occurred in the century after 1750, when European industries sponsored intensive minerological and metallurgical research, and early chemists isolated and identified many new metallic elements — cadmium, cobalt, chromium, zinc, manganese, magnesium, and so on. (These new puzzle pieces helped John Dalton to formulate modern atomic theory in around 1805.) Several synthetic inorganic pigments still used today, including iron blue, cobalt green, cobalt blue and zinc oxide, were discovered prior to 1800.

These manufactured pigment compounds generally have excellent chemical purity and color consistency, and are cheaper to buy and available in larger quantities than natural inorganic pigments. With very few exceptions, all inorganic pigments used in artists’ paints today are industrially manufactured. (Some dry powder natural inorganic pigments are available from specialty pigment retailers.)

As an artist, your primary concern is to understand the generic attributes of these industrial inorganic pigments across different manufacturers and different pigment hues (chemical or crystal variations) — that is, to see paints as physical substances rather than as “colors”. For example, the violet and blue ultramarines are typically granulating and moderately transparent; the many lemon yellow to deep red cadmiums are all powdery, permanent, opaque and quite staining; compounds made with mercury are poisonous and fugitive. The historical information can also help you to understand the rapid expansion in artists’ pigments that occurred in Europe between the 18th and 19th centuries.

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High Gloss Industrial Enamel Surface Coating

Industrial Enamel is a modified single pack urethane enamel made in a high gloss finish. It can be applied to a variety of surfaces including Concrete, Timber and Metal Surfaces that have been primed with a suitable Metal Primer. EPiC Industrial Enamel is for general purpose use.

Features

EPiC Industrial Enamel has excellent durability for a single pack coating. It has very good corrosive and abrasive properties. It is hard-wearing when cured and has excellent Gloss and Colour retention.

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Applications of chrome oxide green

Chrome oxide green, also known as chromium oxide, chromium oxide green, chromium sesquioxide or chromia, is one of four oxides of chromium. It is commonly called chrome green or chromium green when used as a pigment. Chromium oxide is a crystalline green powder, which has been classified as Pigment Green 17 and C.I. 77288 by the Colour Index System.

Its basic chemical composition is Cr2O3. Chrome green is not soluble in water, acids and alkalis. It can be used to refer to a mixture of chrome yellow (Lead Chromate) and Prussian blue (Ferrocyanate). Chrome Oxide Green is used in a wide variety of applications because of its excellent opacity, outdoor durability and heat fastness. Its hardness is also highly valued for surface finishing, where Chrome Oxide Greens are used as abrasive components. They are also used as a base oxide to produce several other metal oxide based pigments.

Chrome oxide green is used as raw material in the preparation of pigments for porcelain, ceramic glazes, plastics, cements, roofing tiles, linoleum, industrial coatings, frits, colored glass, stainless steel electrodes, paints, industrial coatings, inks and as catalyst in the chemical industry. In addition to these areas, it is also used in the production of aerospace super-alloys and refractory bricks for glass and fiberglass industry.

In order to meet the requirements from customers in different lines, we produce several grades of high quality and stable quality chrome oxide greens, they are refractory and technical grade, metallurgical grade, pigment grade, coating grade, construction grade.

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All the information on Cadmium

(a) Plastics

Most cadmium pigments are used in plastics. These pigments disperse well in most polymers to give good colouring and high opacity and tinting strength. The pigments are insoluble in organic solvents, have good resistance to alkalis and in most cases will remain colour fast for the life of the plastic. As a result, cadmium pigments have been used in a wide range of plastic products. Nowadays, their greatest application is in complex polymers which are processed at higher temperatures and require the unique durability and technical performance of a cadmium pigment. Their use is almost mandatory in many nylon, acrylonitrile butadiene styrene (ABS), polycarbonates, high density polyethylene, silicone resins and other modern thermoplastic polymers processed at high temperatures which preclude the use of organic pigments and also most alternative inorganic pigments in the range of hues provided by cadmium. Cadmium pigmented engineering polymers such as ABS are widely used in products which include telephones, gas pipes and fittings, electricity cables, beverage crates and motor vehicle radiator fans. Pigments are usually incorporated in plastics in proportions of 0.01 to 0.75 per cent by weight.

(b) Specialist and industrial paints

Bright cadmium yellows, oranges and reds are major pigments for artists’ colours where their permanence and opacity are the accepted standards against which other pigments are judged.

Cadmium yellows and reds can have service temperatures well above 300 C and are used in coatings for process chemical and steam pipes. They can also be incorporated in latex and acrylic coatings.

Cadmium pigments are usually incorporated in these paints in proportions of 10 to 15 per cent by weight.

(c) Ceramics and glasses

The unique abilities of highly stable cadmium pigments to withstand high processing and service temperatures make them the only choice in much of their colour range for glasses, ceramic glazes and vitreous and porcelain enamels. In transparent glasses the cadmium pigment particles are colloidally dispersed to produce the colours by selective absorption and scattering. The addition of 0.5 percent by weight of cadmium pigment produces bright transparent glasses with colour ranging from intense yellow through to ruby red depending upon the composition.

The bright colours of cadmium pigments are ideally suited to ceramics, vitreous enamels for glass and porcelain enamels for iron and steel domestic products.

(d) Miscellaneous uses

Cadmium pigments have a number of other minor uses in rubber, paper and inks although these are small in terms of cadmium consumption.

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Lead-free transparent frit for ceramic preparation

The invention discloses a lead-free transparent frit for ceramic preparation.

The lead-free transparent frit for ceramic preparation is made of, by weight, 60 parts of SiO2, 20 parts of Al2O3, 5 parts of MgO, 30 parts of CaO and 20 parts of K2CO3. The optimal composition and proportion are determined by screening from a great amount of tests according to the property requirements of the lead-free transparent frit.

Test results show that the lead-free transparent frit for ceramic preparation is scientific and reasonable in component proportion, and ceramic products prepared by the lead-free transparent frit are fine in glaze smoothness, excellent in enamel, especially transparent and bright, free of lead, environment-friendly and wide in application range.

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Introduction of Cadmium Orange Pigmen

Introduction of Cadmium Orange Pigmen

Cadmium Orange pigment is cadmium zinc sulfoselenide (CdS, CdSe) produced by co-precipitating and calcining, at high temperature, a mixture of cadmium sulfide and selenide sulfide in varied ratios forming a partially crystalline structure with sometimes hexagonal or cubic forms.

Cadmium orange pigments are the most durable yellow, orange and red inorganic pigments commercially available. They have excellent chemical and heat stability, and can be used in chemically aggressive environments and durable applications without color fade.

Cadmium sulfoselenide pigments were developed in response to the need for stable shades of cadmium orange to red colors. Cadmium and selenide salts are co-precipitated and then heated to 300°C.

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Applications and process of vitreous enamel

The word enamel comes from the High German word ‘smelzan’ and later from the Old French ‘esmail’. The Collins English Dictionary defines enamel as ‘a coloured glassy substance, transparent or opaque, fused to the surface of articles made of metal, glass etc. for ornament or protection’. Vitreous enamel is specifically on a metal base. It is thus defined as a vitreous, glass like coating fused on to a metallic base. In American English it is referred to as Porcelain Enamel.

It should not be confused with paint, which is sometimes called ‘enamel’. Paints cannot be enamel. They do not have the hardness, heat resistance and colour stability that is only available with real vitreous enamel. Beware of companies or products implying the use of enamel. Check their credentials and warranties.

The glass will be applied to the metal by a various methods either as a powder or mixed with water. This is followed by heating in a furnace to a temperature usually between 750 and 850 degrees Celsius. This ‘firing’ process gives vitreous enamel its unique combination of properties.

The smooth glass-like surface is hard; it is scratch, chemical and fire resistant. It is easy to clean and hygienic.

Vitreous enamel can be applied to most metals. For jewellery and decorative items it is often applied to gold, silver, copper and bronze. For the more common uses, it is applied to steel or cast iron. There are some specialised uses on stainless steel and aluminium.

The durability of the early advertising signs, still showing the brilliance of the original colours after a hundred years, is one of the best examples of the long-term colour stability of vitreous enamel. Compare them to signs, for example road signs, produced in less durable materials which fade and become shabby. Some of the early vitreous enamelled relics date back to the 13th Century BC and the colours are still as vibrant as the day they were produced (see our page on Enamelling History). If you want something where the colour will never fade – use vitreous enamel.

Following the disastrous King’s Cross fire, where combustible materials underground were the major cause, the specification of vitreous enamel for both decorative and functional parts in underground applications is now universal. It cannot burn, in contrast to paints and plastics. The famous London Underground station signs and maps are instantly recognisable uses of this unique product.

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Metals Suitable for Enameling

Enamels for metal normally used on copper work satisfactorily on good cast iron providing certain precautions are taken. Ideally the surface should be sandblasted, however in most instances it is sufficient to use an electric grinder to remove irregular surface areas such as lumps, projections, ridges, rust areas, etc. We do not recommend any casting whether it be cast iron, cast gold, cast silver, etc. be pickled. Castings usually have a few pores where the pickle solutions hide only to come out as blisters in the firing operation.

Best results are normally obtained if the firing temperature is as low as possible. Select enamels for metal which will fire at 1300-13500F for 20 minutes or more. Sifting is not an ideal method of applying the first coat. At these low temperatures individual enamel grains do not flow out easily. If the surface of the cast iron is exposed between grains of enamel it will oxidize during the long firing cycle. Although a second coat may flow out and cover the entire surface the oxidized areas may produce blisters. The best practice is to use Liquid Form – Water Base enamels for the first coat.

For small articles Thompson’s Overglaze Painting Enamel (dry powder) can be mixed with water and applied for the first coat. Cast iron does not require a cobalt bearing ground coat as described above for certain types of steel. Subsequent coats can be normal enamels for metal used on copper if they fire at these lower temperatures. They may be applied by the usual methods. Enamels for metal with expansions of about 240 to 340 are workable on cast iron.

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The Enamel Material

Enamel material comes in a number of forms: lump, string, liquid, and powder, as well as in the optical qualities of transparent, opaque, and opalescent. The important factor in selecting an enamel material is that it be made for the metal you are using. Enamel material expands as it is fired and then contracts as it cools. This is called thermal expansion. The metal on which the enamel material is fired must expand and contract at a slightly higher rate.

Enamels material arc sold in assorted lump forms and in meshes, probably as coarse as 10 mesh and as fine as #325. Some enamelists use the fines for a painting technique. I principally use 80 mesh powder, overglazes, and the 20 mesh in transparents for some jewelry.

Enamels material arc manufactured in soft, medium, and hard fusing, which refers to how they fire. The soft enamels material fire the most quickly. Some enamelists refer to the soft enamels material as delicate. In Thompson’s catalog, most of the 80 mesh enamels material for copper, steel, silver, and gold are listed as medium fusing.

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Industrial Enamel

A single-component, all-purpose, medium industrial enamel.

Designed for interior and exterior use, Industrial Enamel is an all-purpose enamel with a durable color pigment system. Recommended industrial environment uses include properly prepared steel, concrete, wood, plaster, primed aluminum and galvanized steel.

Benefits

  • Good exterior durability
  • High-gloss coating
  • Excellent application properties
  • Exterior/interior all-purpose enamel
  • 450 g/L (3.75 lb/gal) VOC
  • Suitable for use in USDA inspected facilities

Product data is a representative set of attributes and characteristics for this system or product line. Data for individual products may vary and is subject to change.

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