How Long To Leave Hair Dye On?

We like to dye our hair at home. It can be done easily – all you have to do is apply the dye and then wait for the right amount of time before washing it out. I usually use permanent dyes because they are stronger and last longer than normal dyes. I hope you enjoyed this article, please stay on!

- October

What is a Permanent Hair Dye?

Hair dyeing is a chemical process that changes the color of the natural pigment in your hair. It bonds with the dyes molecules, which are then trapped inside the hair strand. There are many different types of dyes available; some are bleach-based and some not.

Permanent hair dyes work by penetrating the hair cuticle and bonding with the hair by changing the molecular composition in the hair cortex. The permanent hair dye is a dye which, after washing out and other processes, does not wash out as many of the hair’s natural pigment cells are replaced with reactive dyes. These dyes, in contrast to temporary dyes which can be removed with shampooing or running water, may persist for up to three weeks.

- October

Apply permanent dye to dry hair using a brush, comb, or applicator. Use color matching strips to determine the best shade and apply color with care at the roots of your hair. Work up the length of your hair in sections and leave on for eight hours or overnight. Shampoo or use color corrector if necessary.

What components of Permanent Hair Dye can be harmful?

There are a number of chemicals in permanent hair dye, including aromatic amines and p-phenylenediamine. Aromatic amines can include Ammonia, Bishydroxybenzene, Methylene blue, and 2-naphthol, while Phenylenediamine (or PPD) includes Picric acid and Hydroquinone.

Some chemicals are known to be harmful, such as amine derivatives, aromatic solvents, and para-aminobenzoic acid. They are all known to cause irritation on the scalp and hair follicles of both humans and animals.


Ammonia is commonly used in permanent dyes to allow the dye to penetrate through the hair cuticle into the cortex. It removes the color from your hair and then you may create a different color of your hair.


While the product is effective, it can cause severe side effects, especially to people with scalp allergies. or sensitivity. Professional hair dye is only made with PPD and has no other chemicals. There are reported cases of women experiencing scalp irritation, acne, eczema, or ringworm while using professional hair dye products as they were not aware of the ingredients in their products. That said, there are some companies that offer mixing kits so you can make your own at home. When using at home, be aware PPD can trigger allergic reactions and increase skin sensitivity.

- October


Peroxide is the active ingredient in hair dyes and it is the bleaching agent. However, peroxide can damage your hair follicles when used in high concentrations because it has been known to cause scalp burns. If you have thin, fine hair that can get fried easily, then this product may not be as great for you as someone with less delicate hair. If you do decide to go for ammonia peroxide, don’t leave it on your hair for more than three hours at a time.

How To Use a Permanent Hair Dye Properly?

1. Follow the instructions

Before using a hair dye, read through the instructions carefully. The packaging of proffesional hair dye always indicates a detailed method of use, namely: for which hair color it can be used, what the expected result will be on your hair color from darker to lighter, how to apply the dye and – most importantly! – how long to leave it on the hair. As a rule, they also give an approximate time for dyeing the roots (if you do not need dyeing along the entire length).

2. For how long to leave hair dye in?

In average, most hair dyes’ instructions tell you to leave it on for 30-45 minutes. If you don’t, the ammonia and peroxide will not go deeply enough into the hair structure and will change its pigments. The procedure can last 30 minutes to three hours, depending on hair length, dye type, and color.

3. What happens if you leave the hair dye on longer?

If you leave the dye on your hair for a long time, various troubles can happen. Paint can damage hair, make it dry and brittle. strands became dull and unruly; hair splits, breaks. In addition, even hair loss is possible. And if the paint is left on for a longer time than the instructions require, the color you will get on your hair may be significantly different from what you expected.

- October

If you dyed only the roots, the shade may differ from the main hair color along the entire length.


When dyeing your hair, you should always be careful not to overdo the dye on your hair and get the desired color. Always read the manufacturer’s instructions and follow them carefully. This guarantees you a new vibrant hair color and a good mood on top of that!