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Sunlight exposure naturally lightens the hair follicles, which makes your hair blonder. The more time you spend in the sun, the lighter your hair will turn over time. Spend as much time as you can outside, and you’ll notice your hair change shades in 1-3 weeks. Make sure you wear sunscreen to protect your skin!  Try to go outside every day, weather permitting. While this may not be possible every day, the more sun exposure your hair receives, the more blonde it becomes. You can go for a walk, lay out on the beach, or ride a bike, for example. If you live somewhere that is warm and sunny year-round, you can do this at any time of year, not just in the summer. Lemon juice is made up of citric acid. When it heats up, lemon juice causes the cuticle of your hair to open and the pigment to lift from your hair. Pour a dime-size amount in your palms, rub your hands together, and run your hands through your hair. Do this right before you go outside, and you’ll notice your hair get even lighter! Wash your hands with soap and water after you apply the lemon juice.  You may need more lemon juice for longer hair. An easy way to apply lemon juice to long hair is to put the juice in a spray bottle. Mist your hair before you leave the house. Additionally, lemon vodka works in similar ways. You can use this as a substitute for lemon juice. Simply pour 1–3 US tbsp (15–44 mL) into your hands, and spread it over your hair. Alternatively, you can mix lemon juice with your conditioner and rinse your hair with it. This lightens your hair over time, instead of only when you are in the sunshine. Pour 1-2 tbsp (14.8 g - 29.6 g) of salt into a spray bottle, and fill the rest with water from your faucet. Then, spray the salt water solution over all of your hair. Do this before you go outside on a sunny day, and within a few weeks you'll notice your hair pigment turning lighter and lighter.  Saltwater helps lighten hair that is already color-treated because the salt opens up your hair cuticle, making it easier for the sun to penetrate the follicles and lighten the pigment. This is a great option if you already have blonde or light-brown hair and want to go even lighter. Apple cider vinegar is great for your hair because it gets rid of oil and residue buildup from your scalp, and it also lightens your hair gently and gradually. To use,  grab a spray bottle and pour in 1 part of apple cider vinegar and 6 parts of water. Spray the mixture over all of your hair. Then, shampoo and condition your hair as normal.  Alternatively, you can use white vinegar as well. Apple cider vinegar works the best, but any vinegar will have similar results. Apple cider vinegar also helps detangle and defrizz your hair. While this helps lighten your hair, it may take several rinses before you see results. Smash 3-5 500 mg vitamin C pills with a can of soup or a rolling pin, and crush the pills until they make a fine powder. Squeeze a moderate amount of shampoo into your bowl, and pour in the powdered vitamin C. Mix the ingredients together, work the mixture through your hair, and cover your hair with a plastic shower cap for at least 1 hour. Rinse your hair thoroughly and apply conditioner. With a few vitamin C washes, your hair may begin to lighten in tone. The proteins and vitamins in beer nourish your hair while opening up the cuticle. To use, open a can or bottle of beer, and leave it out until it is flat and at room temperature. Before you shampoo your hair, pour the beer over your head and massage it through your scalp. Rinse your hair thoroughly, then shampoo and condition as normal. Beer is known to help lighten pigment over time, and it also makes your hair extra shiny. The chemical reaction that takes place when you mix baking soda and hydrogen peroxide can lighten your hair several shades. To use, mix together 1 cup (236.6 g) of baking soda with 3 US tbsp (44 mL) of hydrogen peroxide in a bowl, and apply it to your hair from root to tip. Leave the mask on for 30-60 minutes, then rinse it out completely with shampoo and conditioner.  After you rinse, your hair may look 1-2 shades lighter! Do not leave the mix on your hair for more than 60 minutes. This will cause excessive dryness, and it can damage your hair. Combine 1 tbsp (14.8 g) of cinnamon, 1  c (240 mL) of honey, 1 US tbsp (15 mL) of extra virgin olive oil, and 2  c (470 mL) of distilled vinegar in a bowl until you have a smooth paste. Let the ingredients sit for 30-60 minutes, then apply it to wet hair. Cover your head with a plastic bag or hair cap, and let your hair process overnight. In the morning, shampoo your hair as normal, and your hair may look lighter in color.  Comb through your hair to spread the mixture evenly, or apply it wherever you want highlights Alternatively, you can wash out the mixture after 1-3 hours. This will gently lighten your hair, and you won’t have to worry about sleeping with a plastic covering on. You may have to try this a few times before you see major lightening. If you don’t have cinnamon, you can use cardamom instead. If you have fresh rhubarb, chop up about 1/2 cup (118.3 g) into small pieces. Place your rhubarb in 2 cups (0.5 L) of water, and bring the water to a boil. Cover the pot as the water starts to boil, and remove the pot from heat. Let the ingredients steep for about 10 minutes, and then use a strainer to get rid of the rhubarb pieces. Pour the rhubarb mixture through your hair after you shampoo it, and let your hair air dry.  After several applications, your hair will start to lighten. This works well for medium to dark brown hair. Put 1 tea bag in 1 cup (236.6 mL) of hot water for about 10 minutes. Let the tea cool down to room temperature, then rinse your hair with the tea. Leave the tea on your hair for 15-20 minutes. You can repeat the tea rinse 2-3 times before you shampoo to maximize your lightening potential.  Chamomile is said to lighten hair that is already blonde or light brown. Alternatively, you can use black tea.

Summary:
Soak up the sun for 1-4 hours a day, especially in the summertime. Apply lemon juice to your hair if you want a natural lightening agent. Spray your hair with a saltwater solution to lighten color-treated hair. Rinse with apple cider vinegar if you want to gently lighten your hair. Mix vitamin C pills with shampoo to lighten your hair as you wash it. Try rinsing your hair with beer after you shampoo it. Mix baking soda and hydrogen peroxide to lighten your hair 1-2 shades. Mix honey, cinnamon, olive oil, and vinegar to lighten hair overnight. Rinse with 1/2 cup (118.3 g) of rhubarb to lighten dark hair. Make a chamomile tea hair mask if you want to brighten up light hair.