Strand Test in 5 Easy Steps: don’t forget to do it before you color your hair

before bleaching

It’s very important to do a strand test before coloring your hair so as to check for possible allergic reactions and see how the color will take on your hair.

To do the strand test you must follow these steps:

  • Separate a strand of your hair about 3 or 4 centimeters long, from the back of your head
  • Apply a small amount of dye to the strand that you separated
  • Also apply dye to the inside part of your elbow
  • Let the dye in for 30 to 40 minutes


  It is also very important that you observe how your hair and skin react during the following 24 hours after the test so as to be completely sure that the dye is the right one for your hair. 


Has it ever happened to you that the dye turned out darker than you expected?

Did you apply a light shade and it turned out much blonder than you thought?

Maybe you even started to feel a strange burning sensation on your scalp.

All of this could have been avoided if you had done the strand test.


The strand test is a process that checks three things:

  • Possible allergies to any of the components of the dye
  • Correct choice of color
  • Reaction of the hair to the dye


  If you don’t perform this test, the dye may cause an allergic reaction or the color may be completely different from the one you had chosen. 

Do you think that doesn’t happen?

black and white

Pay attention.

Marisa, one of my clients, decided to dye her hair during her vacations because her gray had started to show.

She chose a light blonde 8 color because the picture of the color in the coloring kit looked similar to hers.


She applied the dye and, when she rinsed and dried her hair, it was completely yellow, like a chicken. Also, her scalp was burning like hell.

What had Marisa done wrong?


Many things, but the main one was that she hadn’t performed the strand test.


 You can’t be blindly guided by the pictures in the dyeing kit boxes, since those colors are retouched by computer programs. 

In addition, to get the same color as in the picture, you should apply the dye on completely white hair.


She hadn’t taken into account other things, such as the underlying shades and the coloring history of her hair.

In addition, as if that wasn’t enough, the dye had irritated her scalp.


Her vacation ended earlier than expected.

The color was the easiest thing to fix because, after a fortnight, she washed it with a purple shampoo.

However, she had to interrupt her vacation to ask a dermatologist, because of the itching and discomfort in her scalp.


“Her distraction” was expensive because, [her_highlight background=”#ffb5e8″]if she had done the strand test, she would have realized that the tone was not the right one, she would have avoided the allergic reaction and would have not interrupted her vacation.[/su_highlight]

Too many “would have” because of not doing the strand test.

Will you continue to push your good luck?


Then, stay with me, because I’ll tell you:

  • How to perform the strand test correctly
  • How to evaluate hair color and health after a strand test

Tabla de Contenidos


How to do the strand test correctly


  • Dyeing kit
  • Gloves
  • Dye brush
  • Plastic container
  • Plastic spoon


Strand test step by step:


Step 1

Comb your hair and separate a 2 or 3-centimeter strand, preferably from the area behind the head or behind the ear.


Step 2

Inside the plastic container, mix 1 tablespoon of dye and 1 tablespoon of peroxide. It is not necessary to prepare all the mixture because, after 45 minutes, the mixture loses strength and must be discarded.


Step 3

Cover and store the rest of the dye and developer perfectly, so you can use it within 24 hours.


Step 4

Put on your gloves and, with the help of the dye brush, apply the mixture evenly on the strand you separated. Also, apply a small amount on the inside of your elbow, to check for any type of allergic reaction.


Step 5

Leave the mixture in for the time indicated by the manufacturer, which will be approximately 30 to 40 minutes.




Afterwards, if you do not have any kind of allergic reaction, rinse the strand and the inside of your elbow with plenty of water and apply a small amount of conditioner to the strand to restore hydration.

Then, wait for your hair to air dry. If it’s completely dry and you feel it stiff or very frizzy, don’t use that hair dye because it means your hair can’t handle the chemicals it contains.


You’ve done the strand test. Now, what?

It’s time to determine the results.


How to evaluate hair health and color after the strand test

before coloring

After the strand test, it’s time to evaluate the color and reaction of your hair to the dye.

I recommend that you wait 24 hours to determine the results of the test because the hair will absorb the pigments better.


 If after those 24 hours, the color is what you wanted and the skin on your arm wasn’t irritated, you can apply the dye on all your hair. 


However, if the results are not what you expected, you will have to make other types of decisions. Let’s look at each case.


  • After the test, the strand turned out very dark.

The solution is simple; you should choose a lighter shade for your hair, which can be up to two shades lighter than the one you used for the strand test.


  • After the test, the strand turned out very clear.

Here we have with two possibilities. The first is that there was a bad choice of color. In that case, you should look for one or two shades darker.

The second possibility is that you used shampoo to rinse the strand, which leads to a fading of the pigments.


  • After the test, the strands are rough and coarse.

Unfortunately, the dye was too aggressive for your hair and took moisture away. Therefore, you will need to repair your hair with coconut oil.

You can do an overnight moisturizing treatment every two days for a week. At the end of that time, test the strand again and see how your hair reacts.

If it doesn’t show signs of damage, you can use the dye on the entire hair surface.

You can also use an ammonia-free dye so that your hair doesn’t run the risk of dehydration.


  • After the test, the strand has unwanted highlights.

You have probably chosen a dye that has orange or yellow secondary pigments.

To solve this, you can tint your hair with blue shampoo for orange highlights, or a purple shampoo for yellow highlights.


  • After the test, the color in the strand is correct, but the skin is irritated.

Whether you notice redness, burning or irritation, you should opt for a semi-permanent dye, which does not contain ammonia or peroxide, even if the strand turned out with a heavenly color.

In addition, it never hurts to ask your family doctor to test for any type of allergy to peroxide or ammonia. He will indicate some alternative dyes for these cases.



The strand test is a simple procedure to avoid many mistakes during coloring, such as the appearance of an allergic reaction, or a bad choice of dye.

It is convenient to observe your hair and skin for 24 hours after the test to detect any change. Only after that time, apply the dye to all the hair.


Now tell me, do you always test your hair before coloring it?

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