There are a few different ways to turn something yellow into brown. The most common methods involve oxidizing the yellow material, adding brown pigments or dyes, or mixing yellow with other colors to create a brown shade.
Oxidation
One of the simplest ways to turn a yellow material brown is through oxidation. Oxidation is a chemical reaction that occurs when a material is exposed to oxygen. Over time, the oxygen interacts with the chemical bonds in the material, causing it to change color from yellow to brown.
For example, yellow metals like brass or copper will slowly oxidize and turn brown when exposed to air. The oxygen reacts with the metal, creating a brownish layer of copper oxide or brass oxide on the surface. This is why older brass door knobs or copper roofs tend to be brown rather than shiny yellow.
Foods can also oxidize and turn brown after being exposed to air. Avocados, apples, and bananas are examples of foods that oxidize. An enzyme called polyphenol oxidase causes oxidation in fruits and vegetables when they are cut or bruised. This reaction turns their flesh brown.
To speed up the oxidation process, you can apply heat. Cooking yellow foods like eggs or baked goods will encourage faster oxidation and browning. The high temperatures break down the pigments and acids in the food, accelerating the reactions with oxygen.
Adding Brown Pigments
Another way to turn a yellow substance brown is by adding brown pigments or dyes. There are a variety of natural and synthetic brown pigments that can be mixed with yellow to create a brown shade.
Some examples of natural brown pigments include:
- Cocoa powder – Made from roasted cocoa beans
- Coffee – Made from roasted coffee beans
- Tea – Brewed from tea leaves
- Turmeric – Ground spice made from turmeric root
- Beet powder – Made from dehydrated beets
These can be dissolved or mixed into yellow batter, frosting, paint, or ink to shift the color towards brown. Generally, the more pigment you add, the darker the brown color will be.
There are also many synthetic brown dyes made from petroleum and coal derivatives. These include dyes like:
- Chocolate brown
- Raw umber
- Burnt sienna
- Raw sienna
- Sepia
Textile manufacturers, paint companies, and printing businesses commonly use these standardized dyes to create predictable brown tones.
Mixing Colors
You can make brown by mixing complementary colors together. On the color wheel, brown is located between the primary colors yellow and blue. So adding blue pigment, dye, or light to yellow will shift it towards brown.
The more blue you add to yellow, the darker the brown tone will get. Here’s an approximate breakdown of how to mix different shades of brown:
| Yellow | Blue | Resulting Brown Shade |
|---|---|---|
| 80% | 20% | Light brown |
| 60% | 40% | Medium brown |
| 40% | 60% | Dark brown |
You can mix yellow and blue paint, dye, pixels on a screen, or gels over stage lighting to create the full spectrum of brown tones.
Alternatively, you can mix yellow with red and green to make brown. Red, yellow, and blue are the primary colors so combining yellow and red makes orange. Adding a touch of green neutralizes the orange into a more natural, muddy brown.
Here’s an approximate breakdown of mixing yellow, red and green to make different shades of brown:
| Yellow | Red | Green | Brown Shade |
|---|---|---|---|
| 60% | 30% | 10% | Light brown |
| 40% | 40% | 20% | Medium brown |
| 30% | 40% | 30% | Dark brown |
With paint mixing, the more primary colors you add, the murkier the brown will get. Start with small amounts and tweak the ratios until you reach your desired shade.
Chemical Reactions
There are a few chemical reactions that can turn yellow materials brown. One example is the Maillard reaction. This occurs when sugars and amino acids are heated together. It causes a cascade of chemical reactions that produce brown pigments called melanoidins.
The Maillard reaction is what gives browned and baked foods like bread, cookies, and roasted meats their characteristic brown color. It doesn’t occur at lower cooking temperatures, only at high heats above 285°F (140°C). The reaction continues as long as heat is applied, getting faster and generating darker browns as the temperature increases.
A similar chemical reaction called caramelization can also produce brown colors. This happens when sugars are heated to 340°F (170°C). The heat causes the sugar molecules to break down into many flavorful compounds, including brown ones.
The process of electrolysis can also turn a yellow metal brown by corroding the surface. Electrolysis involves running an electric current through a liquid or molten salt containing metal objects. This causes the metal molecules to start breaking down, producing rust or oxide compounds. With yellow metals like brass or gold, electrolysis will generate brown corrosion on the surface.
Sun Exposure
Exposing certain yellow materials to the sun’s ultraviolet light can cause them to undergo photochemical reactions and slowly turn brown. This is why yellow paints, plastics, and fabrics tend to fade to a brownish tone after prolonged sun exposure.
The UV light breaks down chemical bonds in the original yellow pigment molecules. New bonds form between the fragments, creating darker pigments that absorb light in the brown part of the visible spectrum.
This photodegradation happens because most organic yellow pigments aren’t very UV stable. Inorganic pigments like cadmium yellow are much more lightfast and resistant to turning brown. Using UV-resistant varnish or sealant can also prevent photochemical reactions on yellow materials.
Staining
Some brown liquids or solids can act as stains and dye a yellow material brown. Common staining agents include:
- Coffee, tea, cola – Contains tannins
- Mustard – Contains turmeric
- Ketchup, barbecue sauce – Contains caramelized sugars
- Chocolate – Contains cocoa solids
- Mud or dirt – Contains iron and organic matter
- Tobacco or nicotine
These staining agents will bond to the molecules in a yellow fabric, paper, or other porous surface, causing a brownish discoloration. With some materials like clothing, the stain can be laundered out. But with other surfaces like antique papers, the staining may be permanent.
Conclusion
There are many options for transforming yellow into brown, whether it’s through oxidation, mixing with other pigments, chemical reactions, sun exposure, or staining. The technique you choose will depend on what kind of yellow material you are starting with and what shade of brown you want to end up with. With a little experimentation, you can find the right approach to turn any vibrant yellow into a mature, natural brown.
