Understanding Optical Brighteners: How Do They Work?

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What is optical brightening agent?

An optical brightening agent (OBA), a fluorescent whitening agent (FWA), or an optical brightener is a chemical compound used in various industries, including textiles, paper, detergents, and plastics. OBAs are designed to improve the visual appearance of materials by increasing their perceived brightness and whiteness. They achieve this effect by absorbing ultraviolet (UV) light, which is invisible to the human eye, and re-emitting it as visible blue light, masking any yellow or dull tints in the material. This process creates an optical illusion of enhanced whiteness and brightness, making OBAs valuable additives in various consumer and industrial products.

How do optical brighteners work?

Optical brighteners, also known as oba optical brightening agents or fluorescent whitening agents (FWAs), are chemical compounds that are used in a variety of products, including detergents, laundry detergents, paper, textiles, and plastics, to make them appear brighter and whiter. These compounds work by absorbing ultraviolet (UV) light and re-emitting it as visible blue light, which enhances the perceived whiteness and brightness of the material. Here’s a detailed explanation of how optical brighteners work:

1. Absorption of Ultraviolet Light: Optical brighteners are organic molecules that possess a conjugated system of double bonds, allowing them to absorb UV light in the 340 to 370 nanometers range. UV light is not visible to the human eye, so when a material containing optical brighteners is exposed to natural or artificial light sources, these compounds absorb the UV radiation.

2. Fluorescence Emission: Once the optical brighteners absorb UV light energy, they enter an excited state. This excited state is unstable, and to return to a lower energy state, the molecules release the absorbed energy in the form of visible light. Specifically, they emit blue light in the 420 to 470 nanometers range.

3. Superimposition of Blue Light: The blue light emitted by the optical brightener ob is superimposed on the reflected or transmitted visible light from the material’s surface. This results in an overall increase in the intensity of blue light, which creates the perception of whiter and brighter colors to the human eye.

4. Neutralizing Yellowing: Optical brighteners are especially effective at counteracting the natural yellowing of materials over time due to factors like aging and exposure to sunlight. The blue light they emit can neutralize the yellow or yellowish tint that can develop in textiles, making them appear whiter and cleaner.

5. Persistence and Wash Resistance: In laundry detergents, optical brighteners are designed to remain on fabrics even after repeated washes. They adhere to the textile fibers and continue functioning, maintaining the desired whiteness and brightness of clothing and linens.

6. Application in Various Industries: Optical brighteners are used in various applications. In addition to laundry detergents, they are employed in the paper industry to improve the brightness of paper and enhance print quality. They are also used to produce plastics, such as PVC and polyethylene, to make them appear more vibrant.

It’s important to note that the effectiveness of optical brighteners can vary depending on factors such as the specific compound used, the material they are applied to, and the quality of the product. Additionally, some people may have skin sensitivities to optical brighteners, so hypoallergenic products are available for those with such concerns.

In summary, optical brighteners absorb UV light and re-emit it as blue light, enhancing the perceived whiteness and brightness of materials. They are widely used in detergents, paper, textiles, and plastics to improve visual appeal.

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How to Remove Optical Brighteners from Clothes:

Optical brighteners are chemicals commonly found in laundry detergents and fabric softeners. These additives make your clothes appear whiter and brighter by absorbing UV light and emitting blue light. While they enhance the visual appeal of your garments, some individuals may prefer to reduce or eliminate optical brighteners due to skin sensitivities or personal preferences. Fortunately, there are several methods you can use to remove optical brighteners from your clothes. In this guide, we’ll explore these methods step by step.

Method 1: Wash with Mild Detergent

1.   Check the Label: Before removing optical brighteners, check the care label on your clothing to ensure the fabric can withstand the process.

2.   Use a Mild Detergent: Switch to a mild, dye-free, fragrance-free laundry detergent. These detergents typically contain fewer optical brighteners.

3.   Wash Separately: Wash the affected clothing separately to prevent the transfer of optical brighteners from other clothes.

4.   Extra Rinse Cycle: Run an extra rinse cycle to ensure that any residual brighteners are thoroughly washed out.

5.   Repeat if Necessary: If you’re not satisfied with the results, repeat the process several times to minimize the presence of optical brighteners.

Method 2: Vinegar Soak

1.   Prepare a Vinegar Solution: Fill a basin or bucket with cold water and add one cup of white vinegar for every gallon of water.

2.   Soak the Clothes: Submerge the clothing with optical brighteners in the vinegar solution and let it soak for several hours or overnight.

3.   Rinse Thoroughly: After soaking, rinse the clothes with cold water until the vinegar smell is gone.

4.   Wash as Usual: Launder the clothes using a mild detergent as usual.

Method 3: Baking Soda Scrub

1.   Create a Paste: Mix baking soda with a small amount of water to create a paste.

2.   Apply the Paste: Gently rub the baking soda paste onto the areas of the clothing with optical brighteners.

3.   Let It Sit: Allow the paste to sit on the fabric for 15-30 minutes.

4.   Rinse and Wash: Cover the clothing with cold water to remove the baking soda, then wash the garment as usual.

Method 4: Commercial Optical Brightener Removers

1.   Choose a Product: Look for commercial optical brightener removers at your local store or online. These products are designed specifically for removing brighteners.

2.   Follow Instructions: Read and follow the product’s instructions carefully, as they may vary by brand.

While eliminating optical brighteners from clothing may not be possible, these methods can help reduce their presence, making your clothes more suitable for those with sensitivities or preferences for less brightened fabrics. Always check clothing care labels and perform spot tests on inconspicuous areas before attempting these methods to ensure they won’t harm your garments.


Is bleach an optical brightener?

No, bleach is not an optical brightener. While bleach and optical brighteners can make materials appear whiter, they work through different mechanisms. Bleach removes color and stains through chemical reactions, while optical brighteners enhance whiteness by absorbing UV light and re-emitting it as visible blue light.

What is Optical brightening agent for paper?

Optical brightening agents (OBAs) for paper are additives that improve the whiteness and brightness of paper products. They work by absorbing UV light and re-emitting it as visible blue light, enhancing the overall appearance of printed materials.

Does oxiclean have optical brighteners?

As of my last knowledge update in September 2021, Oxiclean products did not contain optical brighteners. Oxiclean is primarily formulated to remove stains and boost laundry detergent’s cleaning power, rather than to enhance the brightness of fabrics through optical brighteners. However, product formulations can change, so it’s advisable to check the product label or contact the manufacturer for the most up-to-date information regarding specific Oxiclean products.