1. How does 4D act on hair?

4D performs the interconversion of the cysteine bonds present in the hair fibers, due to the balanced composition of the components.


  1. May 4Dbe left in the hair after application?

There is no problem keeping the product in the hair for more than a day.


  1. How long does the 4Dsmooth effect last?

The "smooth" effect will depend on the type of hair on which the formulation will be applied.

According to tests performed in a specialized technical center the average time on different

types of hair are approximately 4 months, whenever the application instructions are followed.


  1. Is there a difference in performance when applied 4Dto different types of hair?

Yes! Depending on the type, thickness, and level of hydration of the hair fiber there may be performance

differences. In addition, the application protocol is also very important for the effectiveness of the result.


5. After flat ironing and washing the hair for removal of 4D is there a need to brush the hair or iron it?

There is no necessity. The result is visible only by drying the hair naturally or with the aid of a hair dryer.


6. What kind of shampoo should be used after 4D?

Any shampoo can be used for this purpose including shampoos containing sodium chloride (NaCl). It is

advisable to avoid the use of anti-residue or neutral shampoos.The use of sulfate free shampoo prolongs the duration of the treatment.


  1. After how long can I reapply 4Don hair?

After 30 days the product can already be reapplied.



  1. Can I apply 4Din dyed hair?

Yes! However, like any other acidic pH formulation, hair can lose 1-2 tones of color. We recommend using the product before dyeing the hair or apply a 2 tones darker color, wash, and apply 4D.


  1. How long after applying 4Dcan I dye my hair again? 

This will depend on the condition of the hair. If the fiber is nourished, we recommend applying the coloration within the interval of at least one week.


10. Can I apply 4Din discolored hair?

Yes, we even carry out tests that prove that 4Ddo not weaken blond hair to the point of rupture. But hair can lose 1 - 2 tones.


  1. What to do if my discolored hair changes the hue (tones) after the application of 4D?

A qualified professional can instruct you in the best way to correct the hair tone, and may opt for

tinting or toning. We recommend applying products containing 4D before touching

up or getting highlights/streaksor apply a 2 tones darker color, wash, and apply 4D.


12. I use alkaline straightening in my hair. Can I use 4D?

Yes, 4Dcan be applied to hair that has been smoothed by

alkaline processes (thioglycolate, guanidine). However, you should be very careful if you

want to return to alkaline straightening, as they are incompatible with each other and can not

be applied twice in the same place or it will promote fiber breakage. We recommend that,

once hair is processed with4D, discard the other hair straighteners

and keep using only formulations 4D.