Retrobright

Use hydrogen peroxide to remove yellowing from clear or white shells.

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ABS plastic naturally yellows as it ages, which can result in a hazy look to clear shells or a sunburnt look to white shells. Retrobrighting (sometimes spelled Retrobriting) is the process of using hydrogen peroxide to undo this yellowing.

Note that retrobrighting can make shells more brittle, and care should be taken afterward to avoid dropping or other impacts that may damage the shell.

Parts

Cream method

  • Hydrogen peroxide solution
    • The most commonly available recommended product is SalonCare Creme, which is available at most beauty supply stores.
  • Waterproof gloves
  • Small brush
  • Clear plastic bag with seal

Liquid method

  • Hydrogen peroxide solution
    • The most commonly available recommended product is SalonCare Clear, which is available at most beauty supply stores.
  • Waterproof gloves
  • UV light string (example product)
  • Large opaque bin with lid
  • Small clear plastic bin
  • Aluminum foil
  • Glue dots or similar

Process

It is very important to wear gloves when working with concentrated hydrogen peroxide, whether in cream or liquid form. It is not safe on skin and may cause irritaton, bleaching, or other damage at higher concentrations.

Cream method

  1. Thoroughly clean the shell with soap and water to remove any dirt.
  2. Evenly coat the shell with the cream using the brush to get in hard to reach places.
  3. Seal the shell in the plastic bag and place it in sunlight.
  4. Check the shell every couple of hours to see if the yellowing is sufficiently removed. Flip it over occasionally so that both sides get similar UV exposure. Once it looks good, remove it promptly to limit the side effects of retrobrighting.
  5. Wash the shell thoroughly to remove all the cream.

Liquid method

This method involves a little more up-front investment to build a reusable retrobright chamber, but usually results in better, more even results.

  1. Use glue dots to cover the inside of your opaque bin with aluminum foil, including the bottom of the lid.
  2. Use more glue dots to fasten the UV light string to the sides of the bin, looping it around the edges a few times so the light distribution inside the box is fairly even. Your bin is now a retrobright chamber!
  3. Fill the small clear bin with the hydrogen peroxide solution, making sure there’s enough to completely submerge your shell. Place it in the center of the chamber.
  4. Place the shell in the liquid, close the lid of the chamber, and turn on your UV lights.
    • Do not look directly at the UV lights. Direct UV light exposure will damage your eyes. Only turn on the lights when the chamber lid is closed.
  5. Check the shell every couple of hours to see if the yellowing is sufficiently removed. Flip it over occasionally so that both sides get similar UV exposure. Once it looks good, remove it promptly to limit the side effects of retrobrighting.
  6. Wash the shell thoroughly to remove all the hydrogen peroxide.

Resources