Cobalt Zinc Blue Pigment
Cobalt Zinc Blue (Colour Index Pigment Blue 72) is a modification of cobalt aluminate blue spinel pigments (Colour Index Pigment Blue 28). Cobalt aluminate blue pigments are the most durable blue pigments commercially available. They have excellent chemical and heat stability and can be used in chemically aggressive environments and exterior applications without fading.
Pigment Names | |||||||
Common Names (pigment): | English: cobalt zinc aluminate blue spinel French: spinelle bleu cobalt d'aluminate de zinc German: Kobalt Zinkaluminat blauen Spinell Italian: cobalto zinco alluminato blu spinello Spanish: cobalto espinela de aluminato de zinc azules | ||||||
Nomenclature: |
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Pigment Information | |
Color: | Blue |
Pigment Classification: | Synthetic Inorganic |
Colour Index: | Pigment Blue 72 (77347) |
Chemical Name: | Cobalt Zinc Aluminate (Spinel) |
Chemical Formula: | (Co, Zn)2Al2O4 |
CAS No.: | 68186-87-8 |
Series No.: | 7 |
ASTM Lightfastness | |
Acrylic: | I |
Oil: | I |
Watercolor: | I |
Physical Properties | |
Particle Size (mean): | 2 microns |
Density: | 4.49 g/cm3 |
Hardness: | 5.0–5.6 |
Refractive Index: | 1.560–1.662 |
Oil Absorption: | 55 grams oil / 100 grams pigment |
Health and Safety | No acute or known chronic health hazards are associated with this product's anticipated use (most chemicals are not thoroughly tested for chronic toxicity). Protect yourself against potentially unknown chronic hazards of this and other chemical products by keeping them out of your body. Do this by avoiding ingestion, excessive skin contact, and inhaling spraying mists, sanding dust, and vapors from heating. Conforms to ASTM D-4236. |
For a detailed explanation of the terms in the table above, please visit Composition and Permanence.
Origin and History
Cobalt aluminate is identified as the blue pigment on 30 polychromic shards of the 18th dynasty from Theben and Tell el Amarna. The spinel phase has a much lower cobalt/aluminum ratio than modern cobalt blue pigments. It probably contains nickel and zinc, which were found by x-ray spectroscopy. Cobalt salts were first identified in the eighteenth century. The earliest modern history of cobalt aluminate pigments commences with Leithner in Vienna, who appears to have discovered the basic process of calcining cobalt oxide and alumina (aluminum oxide) in 1775. Techniques for manufacturing cobalt blue, the chemically pure salt of cobalt and aluminum oxide, were developed in 1802.
Source
Cobalt blue is cobalt aluminate blue spinel (Pigment Blue 28 or PB 28) with the chemical structure CoAl2O4 of which there are three essential modifications (Pigment Blue 36:1, Pigment Blue 36, and Pigment Blue 72), in which parts of the cobalt are substituted either alone or in combination with chromium and zinc. These variations differ in their tinting strength and hue.
Cobalt Blue Pigment Family | ||
Color | Formula | Color Index |
Cobalt aluminate blue spinel | CoAl2O4 | Pigment Blue 28 |
Cobalt chromite blue-green spinel | Co(Al,Cr)2O4 | Pigment Blue 36 |
Zinc cobalt chrome aluminum spinel | (Zn, Co)(Cr, Al)2O4 | Pigment Blue 36:1 |
Cobalt zinc aluminate spinel | (Co, Zn)Al2O4 | Pigment Blue 72 |
The basic cobalt blue color, Pigment Blue 28, is produced by high-temperature calcination of cobalt (II) oxide (CoO) and aluminum oxide (Al2O4). The variations are produced by the partial substitution of cobalt by chromium and zinc, either alone or in combination with each other. The result is a large variety of cobalt blue pigments that differ in their tinting strength or hues (reddish or greenish blue), depending on the exact chemical composition. The lighter-colored cobalt blue is prepared by adding zinc (II) oxide to the ingredients used for the basic pigment, forming Pigment Blue 72. Blue-green hues are produced by introducing chromium (III) oxide, partially replacing the aluminum (III) oxide in the basic cobalt blue, forming Pigment Blue 36.
All of them form the crystalline modification of spinel during calcination. The spinels are a class of minerals that crystallize in the cubic (isometric) crystal system with the oxide anions arranged in a cubic close-packed lattice, and the cations occupy some or all of the octahedral and tetrahedral sites in the lattice. Spinel minerals form octahedral crystals that are usually twinned. They have an imperfect octahedral cleavage and conchoidal fracture. The hardness of spinel minerals is around 8 (chalk has a hardness of 2-3), specific gravity is 3.5-4.1, and it is transparent to opaque with a vitreous to dull luster.
Permanence and Compatibility
All cobalt blue pigments are chemically inert, absolutely insoluble, have good hiding power and excellent heat stability, and show excellent lightfastness and weather resistance.
Water-Based Paint
Cobalt blue is a semi-transparent pigment with moderate tinting strength in most water-based paint. When it dries, it appears lighter and less saturated. Although pigment particles are very fine, they flocculate, giving a grainy appearance in watercolor. Differences in how the pigment is ground and mixed lead to considerable differences in its performance.
Oil-Based Paint
Cobalt blue is a semi-transparent pigment with moderate tinting strength in oil-based paint. Differences in how the pigment is ground and mixed can lead to considerable differences in appearance.
Oil Absorption and Grinding
Cobalt blue absorbs a moderately high amount of oil, about 55 grams of linseed oil per 100 grams of pigment, to make a paste. It has been noted in some manuals that the pigment works better as a watercolor than it does in oil and is highly valued on that account among moist colors used by artists. Grinding it for artists' use in oil will require 35 percent dry pigment to 65 percent by weight of poppy seed or walnut oil, either of which some artists prefer to linseed oil. Cobalt blue has a greenish tone that is more or less reddish blue when viewed under incandescent light.
Toxicity
Cobalt blue is not considered toxic; however, care should be used in handling the dry powder pigment to avoid inhaling the dust. All toxicological studies showed no signs of toxicity to humans or the environment.
In animal studies, cobalt blue pigments did not display acute toxicity. No acute irritant effect was shown in tests to determine the acute irritation of the skin and mucous membranes. No statistically significant results were found in studies on rats to determine the carcinogenic potential. Soluble cobalt compounds, as well as cobalt metal, may have a sensitizing effect. However, none have been reported during the experience of many years of handling cobalt blue pigments.
Ecology
Since cobalt blue is inert and practically insoluble in water, it does not pose a hazard to the environment. The pigment can be removed mechanically from effluents. No dissolved heavy metals are released into the seepage water on controlled dump sites.
For more information on handling pigments safely, please visit How to Safely Handle Art Materials and Pigments.
SKU | 417-10 |
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Brand | Rublev Colours |
Vendor | Rublev Colours |
Processing Time | Usually ships the next business day. |
Color | Blue |
Pigment Type | Inorganic, Synthetic |
Order Processing
If the Processing Time for items in your order is "Usually ships within 24-48 hours", your order will usually be processed within 48 hours of receipt Monday through Friday. Orders received during weekends and holidays will be processed on the next business (working) day. Orders with longer processing times will be shipped when all items become available.
Shipping Rates
Please add your desired items and the delivery address to your basket to determine the exact shipping costs and options. The table below provides shipping rates for different weights to the countries we ship to.
Carriers
We use the following carriers to deliver orders:
Below is an approximate guide to shipping costs for locations in Europe. Rates may change without notice.
COUNTRY | ALPHA-2 | RATES PER PARCELS | CARRIER | |
0–10 kg | >10 kg–30 kg | |||
Austria | AT | 11,50 € | 11,50 € | DPD |
Belgium | BE | 10,95 € | 10,95 € | DPD |
Bulgaria | BG | 20,25 € | 30,25 € | FedEx |
Bosnia and Herzegovina | BA | 49,25 € | 49,25 € | DPD |
Cyprus | CY | 21,80 € | 29,30 € | FedEx |
Switzerland | CH | 25,85 € | 42,98 € | FedEx |
Czech Republic | CZ | 12,00 € | 12,00 € | DPD |
Germany | DE | 5,50 € | 5,50 € | DPD |
Denmark | DK | 12,00 € | 12,00 € | DPD |
Spain | ES | 17,48 € | 28,50 € | FedEx |
Estonia | EE | 21,70 € | 21,70 € | DPD |
Finland | FI | 17,48 € | 28,50 € | FedEx |
France | FR | 14,60 € | 14,60 € | DPD |
United Kingdom | GB | – € | – € | – |
Greece | GR | 17,48 € | 28,50 € | FedEx |
Croatia | HR | 29,25 € | 29,25 € | DPD |
Hungary | HU | 15,90 € | 15,90 € | DPD |
Ireland | IE | 17,48 € | 28,50 € | FedEx |
Iceland | IS | 30,70 € | 62,40 € | DHL |
Italy | IT | 15,90 € | 15,90 € | DPD |
Liechtenstein | LI | 25,85 € | 43,00 € | FedEx |
Lithuania | LT | 21,70 € | 21,70 € | DPD |
Luxembourg | LU | 10,95 € | 10,95 € | DPD |
Latvia | LV | 21,70 € | 21,70 € | DPD |
Malta | MT | 21,80 € | 30,25 € | FedEx |
Monaco | MC | 15,95 € | 24,30 € | FedEx |
Netherlands | NL | 10,95 € | 10,95 € | DPD |
Norway | NO | 25,85 € | 43,00 € | FedEx |
Poland | PL | 14,90 € | 14,90 € | DPD |
Portugal | PT | 15,50 € | 15,50 € | DPD |
Romania | RO | 21,80 € | 30,25 € | FedEx |
Serbia | RS | 49,25 € | 49,25 € | DPD |
Slovakia | SK | 15,90 € | 15,90 € | DPD |
Slovenia | SI | 15,90 € | 15,90 € | DPD |
Sweden | SE | 15,90 € | 15,90 € | DPD |
Turkey | TR | 27,30 € | 46,20 € | FedEx |
Note: Countries in RED type are not members of the European Union.
Postal Service
Shipping (EU and non-EU countries):
Up to 500 grams Tracked: 6,85 €
Up to 1000 grams Tracked: 10,45 €
Up to 2000 grams Tracked: 20,50 €
Tracking
For tracking details, please log in to your Natural Pigments account.
We track all orders where a tracked delivery service has been selected.
We will update your order with the tracking information if the shipping carrier provides a tracking number. You can locate the tracking number for your order in the shipping confirmation email you receive when your order is shipped. (Look for the email with the subject line "Natural Pigments: Shipment # xxxxxxxxx for Order # xxxxxxxxx.") You can also find the tracking number by signing into your account and visiting My Account Dashboard under Recent Orders.
VAT for Orders within the European Union
VAT is not included in prices unless specified on the website as VAT INCLUSIVE. VAT is calculated for Germany at 19% on both order subtotal and shipping cost and is added to the order grand total.
VAT, Duties, and Tariffs for Orders Outside of the European Union
VAT is not included in prices and totals unless specified on the website as VAT INCLUSIVE. Duties, tariffs, and customs broker fees are not included in the prices and totals on the website. These charges are in addition to what you will pay when ordering. These charges originate in the delivery country, so please contact your local customs for more information.
Shipping Rates
The rate charged for the shipping of your order is based on the weight of your products and your location. Before the final checkout page, you will be shown what the shipping cost will be, and you will have a chance to abandon your order if you decide not to place it.
Shipping Damage
For shipping damage, customers should file a claim with the carrier immediately. Any discrepancy, including wrong or missing items, should be reported to Natural Pigments within twenty-four (24) hours of receipt.
Back Orders
We do not accept backorders for out-of-stock items. If you order an out-of-stock item, we will email you when we expect that product to be available. You will be among the first to receive the item when it becomes available. Natural Pigments will not charge your credit card for out-of-stock items.