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Last updated: July 15, 2022

Swelling or Slipping Foils? Read This!

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3 Tips To Prevent Swelling When Foiling

Do you suffer from slipping foils? Or are foils getting too hot too fast? You’re not alone. To help, we snagged some tips from Schwarzkopf Professional Global Color Ambassador Lesley Jennison (@lesleyjennison) and we’re sharing them below! 


Keep scrolling for advice on how to prevent swelling, getting the perfect processing shot, and Lesley’s double-lock technique to avoid slippage. 



Common client situations where swelling can occur

The best way to prevent swelling is to identify different types of hair that are more likely to swell so you’re prepared. Below, Lesley shared a few specific hair types where swelling is most common:

  • Virgin hair
  • Thicker or coarse hair
  • Darker starting levels 


The science behind swelling

The main culprit of swelling is a chemical reaction. When prepping for a blonding service, there are two main situations when chemical reactions can occur: 


  • Not using proper color bowls. Tupperware or other plastic containers are made with polystyrene. When used to hold lightener, the chemical reaction can cause the product to heat up too quickly and become runny, or begin swelling before it is applied to the hair. 


  • Using an oil-based moisture treatment. We know leave-in treatments are essential to keep hair healthy (especially for thicker-haired clients) but they can actually react with the salicylic acid in the lightener—which can cause swelling.


  • Do this: With Schwarzkopf Professional BLONDME®, Lesley explains, there is no need for additional bond builders. “BLONDME® is our first powder lightener with integrated bond technology,” Lesley explains. “So you’re able to achieve multiple levels of lift while maintaining the integrity of the hair.” 


Pro Tip: “The performance of BLONDME® never changes,” assures Lesley. “Even if there is some swelling or liquefaction the performance will still be incredible.”


3 tips to avoid swelling

Now that we’ve covered how swelling can happen, we’re sharing three easy steps to prevent it! 


1. Switch up the angle of the brush. When first applying the lightener to the section, Lesley keeps her brush horizontal for maximum saturation. Then, she uses the side of the brush to blend the product up and avoid large clumps of product on the hair—which can create uneven lift AND swelling. 


Pro Tip: Adjusting the angle of your brush will also make on-scalp applications easier. “Since I’ve blended that initial line on the first application, it is much easier to blend the scalp application down creating a more even lift,” Lesley explains. 


2. Leave a small space between foil folds. Creating space to allow the air to move freely inside of the foil will help prevent overheating and swelling. That’s why Lesley only folds her foils up once, leaving a small gap (just enough to see through) for proper circulation.


Pro Tip: Maintain space and lock foils in by folding just the corners. “Instead of folding in both sides of the foil, just fold in the bottom and top corners to keep the foil in place,” Lesley explains. 




3. Use the one-third cotton rule. To create more air circulation and extra insurance against swelling, Lesley recommends placing cotton under every third foil. “The cotton acts as a scaffold, holding the foil away so they don’t become bunched together. It is also a GREAT process shot if you’re creating content,” she adds. 




BONUS: Use a double lock to prevent slipping. Foils slipping around the hairline? We’ve all been there. When applying straight to the root, Lesley uses the double-lock technique to avoid slippage. Here’s how:


  • After applying, fold the foil in half past the section leaving a small lip at the top. If needed, fold the bottom half of the again and both sides for extra security. 
  • Place the tail end of the comb just below the lip and gently secure the fold in place.
  • After securing, fold the lip back down leaving a small section of hair visible. Then, double lock by folding the lip back up to align with the section covering the visible hair.





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