Glossers can be used to enhance and refresh colors. This is ideal for a red head. Red hair color is known to fade faster than brunettes. This is due to the red color molecules being larger. The molecules sit on the outer layer of the cuticle, causing them to wash out more quickly. My recommendation is to "layer in the pigments," meaning that after coloring a redhead with permanent color, layer in the pigments with a glosser. (Think nail polish: you apply the paint, then the gel coat, and last you would seal with a top coat.) This will help prolong the life of the red color, keeping it rich and bright!
To keep your vibrancy and your color lasting longer, I recommend 3 things. ALWAYS apply a glosser and shampoo your hair less often. Use a shampoo for color treated hair like Oribe's "Shampoo for Beautiful Color." It contains bioflavonoids to help preserve the red. Bioflavonoids are found in foods such as citrus fruits, green peppers, lemons, limes, oranges, cherries, and grapes. They are responsible for giving fruits their fantastic hues, and protect the hair from fading and discoloration.
We mentioned above that glossers work like a "top coat" for your hair. They act as a color enhancer, like polish on your nails. The more coats you put on, the richer the color looks and the longer your color will last.
For example, here is a picture of highlights with 3 different red tones. The picture on the left does not have a glosser. The picture on the right has been enhanced with a glosser. You can visibly see the difference in vibrancy, color, and richness.
Glossers need to be refreshed every 4-6 weeks. Shampooing less, with cooler water is the key to a longer lasting glosser and less fadage. If you shampoo daily, or only use hot water, it will be closer to 3-4 weeks for a refresh.