How can you identify red ochre?
How can you identify Red Ochre? It's identified by means of FTIR and Raman. Lightfast: excellent. Degradation processes: the pigment has good hiding power and excellent permanence in all media. non toxic. Ocher is not considered toxic, but care should be used in handling the dry powder pigment to avoid inhaling the dust.
Is ocher toxic to humans?
Ocher is not considered toxic, but care should be used in handling the dry powder pigment to avoid inhaling the dust. Fuller. Carl, Natural. Colored Iron Oxide Pigments pp. 281-6.
What is the chemical name of ochre?
Ochre is a family of earth pigments, which includes yellow ochre, red ochre, purple ochre, sienna, and umber. The major ingredient of all the ochres is iron(III) oxide-hydroxide, known as limonite, which gives them a yellow colour. 3, takes its reddish colour from the mineral hematite, which is an anhydrous iron oxide.
What is ochre paint made of?
Ochres are non-toxic and can be used to make an oil paint that dries quickly and covers surfaces thoroughly. Modern ochre pigments often are made using synthetic iron oxide. Pigments which use natural ochre pigments indicate it with the name PY-43 (Pigment yellow 43) on the label, following the Colour Index International system.
What is red ochre?
Red Ochre is an earth pigment containing iron molecules. “The iron molecules in red ochre paint align themselves with magnetic north and when the paint has dried, the direction of the iron molecules can be used to date any artwork that is still in the exact location in which it was first painted (i.e. frescos)" (Zagorski, 2007). Red Ochre has been mined in many places, most notably Western and Southern Australia, Spain, Roussillon and Luberon in France, the Tuscany region of Italy, and the Great Lakes Region in the United States. In ancient times, red ochre was used in religious ceremonies, including burials. Because red ochre is non-toxic it has a history of being used as body paint in many cultures.
What is the color of kermes?
The kermes insect is a cousin of cochineal. It lives and feeds on the leaves and branches of Mediterranean oak trees, known as kermes oaks, rather than cacti that cochineal prefer. The Ancient Egyptians crushed the kermes insect in to make a red dye, which they added to a colorless powder to create carmine lake. The dyestuff was largely produced in the Mediterranean region, where the insects were readily available. Though the color crimson was named after the dye produced by the kermes insect, its popularity as a red colorant was eventually surpassed by cochineal.
Where is cochineal dye found?
Carminic acid is extracted from egg bearing female insects by crushing them. Cochineal insects were originally found and later cultivated in Mexico and Peru, where they feed on prickly pear cacti. Cochineal is currently cultivated in South Africa and the Canary Islands, while Mexico, Peru, Bolivia and Chile remain major exporters. In the 19th century CE, cochineal cultivation was established by the Dutch on Japanese soil to boost their economy. Traditionally cochineal dye was used to color fabric and fiber. Today, the dye is used worldwide as a red colorant in food and cosmetics.
What are the consequences of the presence of iron ochre?
Firstly, the presence of iron ochre will compromise how your drain and pump operates, as the deposits of this substance will cling to the inner and outer walls of the drain, as well as the water inlet of the pump. Further, iron ochre deposits will block drain openings, which will prevent proper drainage following water buildup, heavy rainfall or melting snow. As a result, water will begin to accumulate around the foundation of your home, as well as under the concrete slab.
How to treat iron ochre?
Another way to deal with iron ochre is to opt for bactericidal and chemical treatments. These treatments will directly affect the elimination of the Ferro-bacterium present in the soil while controlling the pH of the soil.
What causes iron ochre to form?
Iron ochre deposits are a result of the presence of iron, oxygen and water in the soil. Specifically, the appearance and growth of ochre depend on a biological reaction, a chemical reaction or a combined effect of the two. The chemical reaction that creates iron ochre happens due to the presence of iron in the soil and is drawn up ...
What happens if you sell your home with iron ochre?
If you decide to sell your property, an assessment is also required. This will give you the upper hand if the presence of iron ochre is detected , as you will avoid any legal action from new owners. It's important to remember that it is not so much the presence of iron ochre itself, but instead the damage it can cause to a property or home in the long run.
Why does iron ochre appear on concrete?
Another common cause of iron ochre is having very high humidity in your home . This will be visible by the appearance of mould and condensation on your windows, and moreover, traces of efflorescence can appear in the bottom of concrete walls. Photo: Pixabay.
What are the conditions that make iron ochre?
Certain conditions will be favourable for the appearance of iron ochre, and these include: The presence of a filtered drain; If you have a drain that is warped; The presence of sandy soil; A soil which has a neutral pH level, or is close to neutral, and therefore around 7 ;
Is iron ochre bad for you?
Due to the severe damage it can cause, iron ochre is an enemy to watch out for. This oxidizing iron substance deserves special attention, whether for the current homeowner who has dealt with its negative effects or for the potential homeowner, who fears having to deal with it. Regardless, here is all of the relevant information you’ll need ...
Overview
Earth pigments
Ochre is a family of earth pigments, which includes yellow ochre, red ochre, purple ochre, sienna, and umber. The major ingredient of all the ochres is iron(III) oxide-hydroxide, known as limonite, which gives them a yellow colour.
• Yellow ochre, FeO(OH)·nH 2O, is a hydrated iron hydroxide (limonite) also called gold ochre.
Historical use in art and culture
Yellow and red ochre pigment was used in prehistoric and ancient times by many different civilizations on different continents. Evidence of the processing of ochre to a lesser extent, in Africa and Europe has been dated by archaeologists to 300,000 years ago, evidence of use in Australia is dated to 50,000 years ago, and new research has uncovered evidence in Asia that is dat…
Modern history
The industrial process for making ochre pigment was developed by the French scientist Jean-Étienne Astier in the 1780s. He was from Roussillon in the Vaucluse department of Provence, and he was fascinated by the cliffs of red and yellow clay in the region. He invented a process to make the pigment on a large scale. First the clay was extracted from open pits or mines. The raw clay contained about 10 to 20 percent ochre. Then he washed the clay to separate the grains of san…
In heraldry
Ochre, both red and yellow, appear as tinctures in South African heraldry; the national coat of arms, adopted in 2000, includes red ochre, while (yellow) ochre appears in the arms of the University of Transkei.
In Popular Culture
A reddleman named Diggory Venn was prominently described in Thomas Hardy's 1878 novel entitled The Return of the Native.
See also
• Falu red
• Female cosmetic coalitions
• Iron(III) oxide
• List of colors
• List of inorganic pigments
External links
• Pigments through the ages
• A recipe for red ochre paint.
• Aboriginal Art Online Use of ochres in traditional Aboriginal art.
• National Museum of Australia Collection of ochre samples.