Which one, pick one. . .
Foil caps, traditional shower caps, disposable shower caps, plastic bags to cling film, the best way to cover your hair for maximum conditioning seems to be an ever-changing answer. In truth, “the best” method varies, depending on what type of deep-conditioning you are doing, as well as the characteristics of your own hair. Knowing the benefits of each option will help you select the best of these tools for your particular conditioning needs.
Foil is great for speeding up the work of ingredients that penetrate the hair, part of why foil wraps are widely used in highlighting. The metal is a great conductor, which works excellently for ingredients which need to be heat-activated to work.
Foil caps are not that great, however, at keeping moisture in the hair – especially if you are using a dryer in place of a steamer, your foil-covered hair can become dehydrated fast. The elastic on these caps tends to fail pretty quickly and foil strips can't provide full enough coverage under the baking heat. Plus as a good conductor, it's little surprise that foil is not the best of insulators.
Plastic Shower Caps
Plastic shower caps come in two varieties, and one tends to outshine the other when it comes to conditioning. The thin, usually see-through disposable variety is the most widely-used conditioning cap by hairdressers and it's not hard to see why.
Purpose built for steaming, these caps encourage the hot, wet air to build up inside their bilious interior space. They are great insulators, and the elastic band at the hairline keeps the cap on snug. as long as it is not reused too many times. Still, while the material they are made with holds onto moisture well, overuse can allow water to escape at the sides as the elastic gets loose, and the plastic itself can get damaged. So remember to replace them as soon as you notice the slightest hint of loosening.
Where these conditioning caps tend to slip up is on longer or thicker hair. Usually not available in extra large sizes, they are often too small to steam a headful of thick, lengthy tresses while providing good coverage to all of the hair. What's more, should they slip off the hairline, they can leave vulnerable tresses exposed to drying heat, if a dryer is used as a heat source. An important note: If placed directly on the hairline, the elastic can have an erosive effect on your edges, so always remember to keep them pulled forward and off this delicate area.
A lot less successful in the conditioning stakes is the at-home variety of shower caps. Designed for re-use, these tend to be made from bulkier, heavy-duty material to ensure durability. Given that they are built more for comfort than conditioning efficacy, the bands around the hairline to keep the shower cap in place often do not fit to the head as closely as some of the other options.
Unlike the caps used in the salon, they are principally intended to keep splashes of water off your hair as you shower, so they don't usually do a good job of keeping moisture locked in.
Also known as plastic wrap, this is the best option for the drippiest of treatments, like infusions or at-home mixes, which would easily flow out of the rims of other options. Its flexible structure allows it to fit perfectly and precisely to your head shape, making it the most secure.
Downsides are typically a case of user error. For instance, not wrapping the cling film on quickly enough can cause it to lose its tackiness, especially as it becomes wet with product. Also, if it's not wrapped on tightly enough, it can slowly come loose during the conditioning process. Another common failing is leaving gaps during application. While cling film is usually the most watertight solution going, water will escape away from any gaps left, so be sure to apply it as thoroughly as possible, double wrapping some sections as necessary.
Aside from user error, wrapping hair with cling film can be problematic for those with very thick or long hair, especially if tangle-prone. To get all the hair sealed in, it does require that you pile up, doobie, or randomly compress your hair against your head, processes which many tangle-prone folk are loath to do on wet hair. The compression required to keep the cling film in place can also work against treatments that perform best with a little bit of space for the warm, wet air to circulate to each and every strand.
If you run out of every single one of the other conditioning items, you’ll probably still find one of these lying around. Not only do they have the highest availability and lowest cost of any on the list, plastic bags also have some functional advantages.
For one, they are extremely adjustable – just tie it to fit the size of your head. They fit pretty securely, too (though not as secure as the cling film), so moisture won't easily escape.
Best of all, they are also roomy, great for long hair or thick hair, since you don’t have to tie it up and risk tangles. This ample space also makes it easier for the humid air to float its way through your stands, unlike with cling film where your hair is compressed.
Tips for all methods
If you're using a conventional steamer, water and heat loss from these caps is not a problem as the steamer will simply infuse more vapour back into your hair. However, leakage can be a problem if you are using only your body heat to deep condition your hair, so be extra-vigilant about water-tightness when conditioning this way. If your heat source of choice is a hair dyer, seepage is a major deal. Under a dryer, the hot, waterless air can wick away your hair's moisture very quickly, defeating the purpose of a hydrating DT. For best results with this method, sit under the dryer for no more than 10 minutes. Then, come out and allow the heat that you've trapped under your conditioning solution of choice to deep treat your hair the rest of the way.
Need a quick re-cap on the optimal method for your hair? Consult this chart:
DHA Hair Care Experts