Should you be washing your hair with hot or cold water? 
There are advantages and disadvantage to washing your hair with hot or cold water; but is one temperature better than the other; and is there a perfect routine?
 

Washing your hair with HOT water (+/-)

+ Hot water rinses oil and dirt
Hot water is the best temperature for washing hair that contains a lot of dirt, oil or product build-up. The heat from the water opens the hair cuticle open, allowing shampoo to more deeply clean.

+ Hot water dissolves hair products
Heat speeds up the rate that cleansers can dissolve product residue. This allows you to more effectively clean your hair before applying new product.

– Hot water can make your hair overly porous
Hot water can dehydrate the scalp, resulting in reduced moisture in the hair. It can also dry your hair as it strips it of its natural oils – making it vulnerable to breakage.

– Hot water causes frizz
Every type of hair needs moisture to stay frizz free. As hot water strips the hair of natural oils, moisture escapes the hair shaft and can leave your hair frizzy.
 

Washing your hair with COLD water (+/-)

+ Cold water makes your scalp cleaner
Cold water shuts the hair cuticle and also closes your pores. By rinsing your hair with cold water, you protect the scalp pores from things like dirt, grease and oil. Also, if your pores are sealed, then you are also much less likely to suffer from hair fall.

+ Cold water makes your hair shinier
Cold water will close the hair cuticle, resulting in a smoother, glossier surface. This is exactly the same as using cold air from a hair dryer to reduce frizz and add shine.

+ Cold water seals the moisture in your hair
On closing the hair cuticle, cold water also seals in moisture. Whereas hot water can remove the moisture from your hair, cold water retains the moisture and the hair’s natural sebum.

+ Cold water improves the blood circulation to your scalp
When you’re cold, your blood moves faster and your capillaries widen to warm you up. Blood will rush to the scalp and hair roots, giving them all the valuable nutrients they need to stay healthy. It should also be noted that poor blood circulation can contribute to causing hair loss!

– Cold water can be uncomfortable
Showering in a cold shower is not pleasant, especially in winter.

– Cold water can reduce the volume of your hair
Cold water can make your hair look less dense and reduce its volume.
This could be a concern for guys who have naturally thin hair.
 

Hot or cold water: The perfect hair washing routine?
I’d always recommend using warm water (not hot water) to wash and condition your hair. Slightly cooler water (not scorching hot) will limit the amount of damage you could potentially do your hair, but also allow you to cleanse the hair of product build-up.
 
Use cold water for your final rinse in order to seal and protect the hair. Choose a temperature that you feel comfortable in!
 
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By Kendra Aarhus
Women's Hairstyles Expert
 
1: Turning the Heat to High on Your Flat Iron
Just because your flat iron goes up to 450 degrees, doesn't mean you should turn it to high. Of course there are some exceptions to that rule, like when you're in a super hurry on the occasional night out, or if you hair is incredibly course and unruly and a high heat is necessary for the look you want (even then, keep that occasional). The finer and thinner your hair is, the less heat it can handle, so using your hot tools at a responsible temperature will keep your hair from becoming damaged.
 
A good heat protection spray is also a good idea, but heat protection doesn't mean your hair can't be damaged from heat. It simply helps prevent damage, but does not guarantee it.
 
2: Never Getting a Haircut While it Grows Out
I can completely empathize with the agony of growing your hair out. It's such a long process, but never cutting your hair while you're growing it out is one way to guarantee your hair will look awful. While cutting your hair doesn't actually make it grow faster, as you may have heard, it does clean up the split ends and prevent your hair from breakage. Split ends break your hair off, causing the length to shorten from the ends.
 
Bottom line: get a haircut at least every 8-12 weeks while you're growing your hair out and work with your hairstylist to trim as little as possible for the healthiest hair and optimum hair growth.
 
3: Using Shampoo Completely Wrong
From not washing properly to not rinsing thoroughly, the sins of shampoo use are vast. Shampoo should be used to clean your scalp, not necessarily your hair. Sound confusing? Fortunately if you're properly cleansing your scalp, your hair will get clean in the process. To wash your hair the right way try these tips:

• Choose a shampoo that addresses your scalp issues.
• Scrub your scalp with the tips of your fingers, not your fingernails.
• Be sure to pay special attention to the back of your head, directly behind your eyes as that's the spot people miss and build up can get pretty gross.
• Rinse really, really well for 30-60 seconds with clean water.
• Repeat the shampoo once or twice until the shampoo easily creates suds when applied to your scalp.
• When in doubt, rinse again. 

4: Shampooing Daily
The idea of not shampooing my hair daily was simultaneously the hardest and most rewarding hair decision I've ever made. Dirty hair seemed like a deadly sin, if you asked me. Not only does daily shampooing dry your hair and scalp out, it also strips your hair color, invites split ends, and influences frizz. Even if you can switch to every-other-day shampooing, you can improve the overall health of your hair, extend the life of your color, and some say even grow your hair faster.
 
5: Choosing a Haircut for Someone Else
As a hairstylist, the idea of keeping your hair at a particular length or style because someone else told you to drives me up a wall, and it's keeping you from experiencing possibly the best cut or style of your life. So despite what your best friend, your husband, or your grandmother says; yes, you can wear short hair, and no, you don't have to have a perfect shaped face for those layers. Throw the ideas of the world out the window and choose a haircut based on your lifestyle, and for crying out loud, if you want to try that pixie cut before you're 80 years old, then do it.
 
6: Unrealistic Expectations
For crying out loud if you listen to one piece of advice from me ever in your life, please listen to this. If you bring your stylist a photo of a hair cut with pin straight hair and light wispy layers but you have thick curly hair, unless you intend to spend one hour every day making your hair pin straight your stylist can physically not make that happen, ever. If you want your hair to look like the photo, you have to be willing to put the effort into your hair that will be required.

My advice, embrace your hair's thickness and texture and find photos of hairstyles that closely resemble the hair you are living with right here, right now.
 
7: Being Completely Clueless About Your Hair Products
If you're a product junkie, this is your cue to pay attention. I have no real issue with product junkies, I'm certified myself, but product junkies with no real purpose or understanding of the products they're purchasing are committing a huge hair sin. Not only are you probably missing out on some great product benefits, but misuse or overuse or hair products can cause serious buildup that can lead to hair damage.
 
Get knowledgeable about your hair products by talking to your stylist or reading reviews by people that know what they're talking about.

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