Temporary hair dyes make it easy to switch up your color using a non-permanent hair dye alternative — you’ll score tons of compliments, and the best part? It’s only temporary! The only other thing you should differently when you have gray hair? Limit how often you use hot tools. Both Dr. Fusco and de Zeeuw say that heat can make already dry hair even more dehydrated. If you do need to use a blow-dryer or flat iron, prep hair with a heat protective spray. Gray hair can also develop a yellowish tint — not unlike the plight that blondes are familiar with. So, the other concern is neutralizing these unwanted brassy tones so that gray hair looks shiny and vibrant. To achieve this, Linda de Zeeuw, master colorist at Rob Peetom Salon in New York City, says to use a color-depositing shampoo or conditioner or a gloss, and to avoid styling products that have gold tints to them all together.

Use these [color-depositing] products once every three weeks, because they add pigment to the hair," she explains. "If you use them during every wash, it will cause too much build-up of pigment which can make the hair look darker or even purple!" Many colorists get asked how to transition to gray if you've been coloring your hair for years. Korab advises "to either let your natural hair grow out fully or see a salon professional who can guide you in the right direction." While going gray or silver can be fun and a welcome change, it does require some maintenance and upkeep. Korab suggests touching it up about every four weeks and consistently using a shampoo formulated for silver or gray hair, like Oribe Silverati Shampoo or Redken Color Extend Graydiant Shampoo. How we test at-home hair color

The verdict: Root cover ups

Hair mascara isn't just for covering up grays: it's an easy technique to add a fun pop of bold color. Apply the wand directly to your hair and brush on some color. It's the most temporary dye, lasting just 1-2 shampoos. The GH Beauty Lab evaluates root touch-up products both in the Lab using technical instruments and on consumer or expert testers. Temporary root touch-up products are assessed by testers on factors including ease of application, color coverage (including gray) and blending, transferring and staining, flaking, lasting power and ease of removal. We already know that it affects both our skin and our joie de vivre, and now new research has shown the toll stress takes on the colour of our hair. The study, published this week by Nature, found that mice who endured stressful events were more likely to have grey hair, thanks to an acceleration of the process by which pigment (which makes up hair colour) is produced. Put simply, when our nervous systems are put under stress, we run out of the stem cells that change into pigment-producing cells faster than we would if they weren’t. Cue grey hair. Sprays and powders are best for camouflaging large areas of regrowth and the scalp, as they can deliver high pigment load with a single application, Aral says.

In the Beauty Lab's permanent root touch-up products test, scientists dyed human hair samples in brown, red and blonde shades mixed with gray, then assessed initial gray hair coverage and shine using the Chromameter machine. Next, each dye's color retention was gauged by putting the dyed hair samples through 20 wash and dry cycles using the Swatch Wash Station and four hours of UVA light exposure with the Q-Lab QUV Accelerated Weathering Tester. Final Chromameter readings where taken, then Beauty Lab scientists assessed color change in the dyed hair samples to determine how well each resisted fading. S emi-permanent hair dye lasts at least a week. "Semi-permanent hair color molecules are larger, so they don't penetrate into the hair and instead act as a stain in the cuticle layer of the hair," explains Diaz.

Here are the best products to embrace your greys or blend them away...

There's a catch, though: If you have ultra-light, natural hair, even temporary color might wind up being more permanent. "The darker the temporary color and the lighter the hair, the longer it will take the color to wash out," warns O'Connor. It won't necessarily ruin your natural hair color, but it may alter it for a bit longer than you hoped for. What is the best temporary hair dye? John Mouzakis is a stylist and co-owner of 3rd Coast Salon in Chicago. He has over a decade of experience in the industry, working as both a hairstylist and educator across the globe.