I feel like working in a hair salon, one of the most common errors I feel that people find is when they go to the store, and they buy a hair color that they thought was going to be temporary. Suddenly, it's the wrong color, and they can't get it out of their hair.
I feel that part of the problem is the marketing on products. The marketing on products gives a very big leeway on what the products are allowed to say. So for example, you might see a product that says "lasts two to three shampoos." In your head, that sounds very temporary, and I would agree. I would absolutely agree.
How do you decipher in the store what's going to wash out and what's going to stay a little longer than you wanted it to? One tip I have is this. Any time you have to mix two bottles together, two bottles together equals a developer and a hair dye. By mixing two bottles together, you're making the product come alive. Once the product can come alive, it's going to alter your hair a little bit more.
A real temporary hair dye is just one bottle. Temporary hair dye is used best to either slightly change the tone of your hair, maybe go one shade darker than your hair. Some temporary dyes are used on gray hair to take the yellow out. The number one thing to consider if you'd like to buy a temporary color is that you're not mixing two thing together. You'll know that it's going to wash out.