Copperas, iron(II) sulfate or green ferrous sulfate, is a versatile compound in various applications, from agriculture to water treatment. A unique aspect of copperas is its ability to change color through a simple chemical process. Here are the basics of making copperas red.
Understanding Copperas
Copperas is typically found in a greenish crystalline form known as green vitriol in alchemy. It's added to soil to improve plant growth. It provides essential iron, the "ferrous" part of its name, a crucial nutrient for many plants. It's even given to treat iron deficiency in humans.
It's used in dyeing fabrics, making ink, and as a mordant in the textile industry. The red hue of copperas is often associated with its oxidized form, while the green color is typically seen when it is in its hydrated state.
The pigment derived from copperas is significant in art, architecture, and traditional crafts, adding vibrance and depth to creations throughout history. Its unique properties and color variations make copperas a valuable material in aesthetic and practical uses.
The Science Behind Color Change
The color change in copperas comes from the oxidation of iron ions, causing rust. In its ferrous (Fe2+) state, it looks greenish. On heating, ferrous sulphate crystals lose water and anhydrous ferrous sulphate FeSO4 is formed.
The color changes from light green to off-white. On further heating, anhydrous ferrous sulfate decomposes to form ferric oxide (Fe2O3), and sulfur compounds. When iron is oxidized or exposed to oxygen to reach its ferric (Fe3+) state, it takes on a reddish hue.
At this point the rust pigment copperas red is made. Cool and grind or sift as desired. The pigment can go down to a very fine grain. It doesn't dissolve in water, or binders like linseed oil. The tiny particles reflect light bringing an extra shimmer to the glaze or other artwork.
Hematite is often responsible for the red color of earth, rocks and clay pigments, owes its intense color to magnetic interactions. Oxidized iron (Fe3+) is most associated with the red color of soils, sedimentary rocks and weathering products.
The oxidation process can happen over time. It can be sped up through several methods.
Methods to Make Copperas Red
Oxidation with Air Exposure
It's suggested to buy the green copperas or ferrous sulfate, because making it involves sulfuric acid and dangerous processes. Here's the link.
Materials Needed:
Copperas (iron(II) sulfate)
Open container
Procedure:
Place your copperas in an open container in a dry area.
Allow it to be exposed to air for several days.
Over time, the copperas will oxidize and gradually turn from green to a reddish-brown as iron ions are oxidized to ferric form.
Using Hydrogen Peroxide
Materials Needed:
Copperas
Hydrogen peroxide (H₂O₂, a 3% solution is commonly used)
Procedure:
In a glass or plastic container, take a solution of copperas and dilute it with some water.
Slowly add hydrogen peroxide to the solution while stirring gently.
The oxidative reaction will cause the color of the solution to change, resulting in a red hue almost immediately.
Heat Treatment
Materials Needed:
Copperas
Heat source (like an oven, Bunsen burner or hot plate)
Procedure:
Place the copperas in a heat-resistant container.
Apply heat carefully and gradually until the copperas is fully dried (around 200°C or 392°F).
As the moisture evaporates from the copperas, it will oxidize and should turn a reddish color.
Safety Precautions
This is a non-toxic substance. However, when working with any chemicals wear gloves, safety goggles, and a lab coat or apron. Make sure the working area is well-ventilated, particularly when using hydrogen peroxide or heat. Properly dispose of any leftover chemicals.
Applications of Red Copperas
The transformation of copperas into its red form has practical applications. Red ferric sulfate has uses in various industries:
Pigments: The reddish hue can be used as a pigment in paints and coatings.
Water Treatment: It can be used in certain water purification processes.
Agriculture: Like green copperas, the oxidized version also provides iron to plants, aiding their growth.
Copperas Red can be filtered down until only the finest color remains, the "bullion" of the rust. The color is often added to paint. Water soluble, it's a good mordant and/or dye. It's has antiseptic properties, and no known toxicity. Use as is, or add other natural colors like ocher.
Making copperas red is a fascinating process illustrating the transformative power of nature. By using simple methods like exposure to air, hydrogen peroxide, or heat treatment, it's an entertaining adventure to achieve this color change.
Impact on Industry
The early modern copperas processes coincide with industrial advancements in Europe, particularly in Britain. By the 19th century, the increasing demand for dyes and inks coupled with the agricultural revolution create a booming market for copperas.
Non-Fiction Books:
Fiction Books:
READ: Lora Ley Adventures - Germanic Mythology Fiction Series
READ: Reiker For Hire - Victorian Detective Murder Mysteries
Comments