Can You Reuse Hair Dye After Opening It?

Hair dye allows us to radically change our appearance and the many colors available range from muted to bleach blond to beyond vibrant. However, there are a million products out there, and many different methods and types of dye. Each has its own system, and there are different rules for different products.

In order to understand them all, you need a cosmetology license!

Here’s one of the most common questions that we get about hair dye: “Can you reuse hair dye after opening it?”

It depends on the type of dye, and whether it’s been mixed with a developer. You may be able to reuse hair dye as long as it is fully sealed and hasn’t been mixed with a developer.

If you hate the idea of wasting your hair dye, in this article we’ll discuss how you can ensure that it lasts as long as possible and the cases in which you can still use it if you have some left over.

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Can You Reuse Hair Dye After Opening It?

The first thing that you’ll have to determine is the kind of hair dye that you’re using.

Semi Permanent vs Permanent Hair Dyes

If you have to mix your dye with a developer, it’s almost certainly a permanent dye. These dyes will not last long after they’ve been opened, and once they’ve been mixed, they need to be used in about 30 minutes or they go bad.

The most common type of hair dye that people may expect to have leftover at home is the kind that comes in a box that you can typically find at pharmacies or on amazon.

Or you may have some hair dye in a tube that you got from a professional salon.

These are all likely permanent hair dyes, and will likely have varying expiration dates.

Be sure to always check the box or tube that your hair dye came in to determine whether you should still be able to use it or not.

If a hair dye is past its expiry date, then it will not penetrate your hair as effectively. And it may even get to the point where it could be harmful if you expose your scalp to it.

If you’ve run into this issue, our article on how to hydrate hair after bleaching may be of some help.

Even though most hair dye is supposed to last for a long time, be sure to check the expiration date for yourself.

Semi-permanent dyes, on the other hand, do not get mixed with a developer. Once opened, they can last for as much as a year if cared for. But this brings us to the next issue.

Storage and Sealing

A great deal depends on how well-sealed a semi-permanent dye is. Did you put the cap back on completely?

Semi-permanent dye reacts with oxygen in the air to produce color, but it doesn’t work as deeply (nor does it last as long). If these products are completely sealed from oxygen getting to the dye, they should last for up to a year.

Semi-permanent dye reacts with oxygen in the air to produce color, but it doesn’t work as deeply (nor does it last as long). If these products are completely sealed from oxygen getting to the dye, they should last for up to a year.

Leftover Hair Dye

So let’s say you’ve opened your hair dye and decided that you don’t need to use all of it to dye your hair. Can you reuse hair dye after opening it? How long will mixed hair dye last?

The key question is: did you mix the dye with a developer? If so, it has undergone a chemical reaction that activates the hair dye. Most types of permanent hair dye will have to be mixed with peroxide (H2O2).

It is the main ingredient in hair bleach.

When mixed with peroxide, hair dye will be able to penetrate the shaft of your hair and alter the color. If you were to apply a hair dye solution without mixing it first, then it wouldn’t even alter the color of your hair.

Unfortunately, mixed hair dye will also be rendered unusable soon after you mix it with peroxide.

If your leftover hair dye has been mixed with peroxide, then it’s time to throw it out. It will soon start clumping up and eventually be useless anyway.

Can You Reuse Permanent Hair Dye That Has Not Been Mixed With Developer?

If you haven’t mixed your permanent hair dye with peroxide, can you reuse it? Yes, you can likely store excess hair dye and developer for later use assuming they have not been mixed. Make sure you seal everything to make it completely air tight (in separate containers).

If you do that, you should be able to reuse the hair dye at a later date.

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Can You Reuse Semi-Permanent Hair Dye After Opening It?

Whether or not you’ll be able to reuse semi-permanent hair dye depends on the kind of package that it comes in. Since most semi-permanent hair dye is designed for a single use and not several, you most likely won’t be able to use your semi-permanent dye at a later date.

This is especially true if it comes in an unsealable packet.

However, there are pricier semi-permanent hair dyes that are meant to be used on several occasions, and these will typically come in resealable packs, tubes, or even hairspray cans.

If the packaging of your semi-permanent hair dye has clearly been designed to be used again later, then the dye likely won’t go bad.

Most semi-permanent dyes aren’t designed to react with peroxide, so you won’t have to worry about mixing before use.

Instead, these semi-permanent dyes will react with oxygen in the air, so you’ll typically find this kind of dye stored in containers that are airtight, preventing oxygen from getting in.

If the packet will expose the dye to oxygen before you’ll be able to use it again, then the dye will be activated and it will soon be unable to adhere to your hair.

At this point, you may as well throw it out, as the hair dye is about as useful as a permanent hair dye that has already reacted with peroxide.

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How to Save Your Hair Dye for as Long as Possible

You have a few options if you’d like to save some money on your hair dye and reuse your current packet in the future.

Estimating Need

The first thing to consider is that you’ll get better at estimating the amount of hair dye that you need to give your hair the right color over time.

When you can estimate the amount of hair dye that you’ll have to use, you can lay it out and quickly seal away the rest in a container to ensure that it doesn’t react with the oxygen in the air. If you’re working with permanent hair dye that you’re supposed to mix with peroxide, don’t mix all of it.

Leaving a little bit of permanent hair dye in the box or the tube will allow you to save it for the future when you can mix it with peroxide and eventually activate it for use.

Get a Friend to Help

Another great way to ensure that you save as much hair dye as possible is to let someone else dye your hair. Since we can’t exactly see the entirety of our head when we’re dying our hair, it becomes more difficult to measure out the right amount of hair dye for use, and we tend to use too much of it to be safe.

If you have a friend or family member that can apply the dye to your hair for you, you’ll likely be able to use your hair dye more efficiently, saving you money. Getting someone else to dye your hair may also save you time, as it will be easier for them to apply the dye and the task will be done sooner.

See also:

• Can You Wash Your Hair With Dish Soap To Remove Color?