Methods of Treatment: Go to this website for detail information. http://www.retrofixes.com/2013/10/how-to-clean-whiten-yellowed-plastics.html The following information listed below is for review only.

Pure Hydrogen Peroxide with no additives. This is the easiest method and perfect for small items. The peroxide strength ranges from 3% to 12%. Higher concentrations above %3 can only be purchased from Hair Salon stores. This is the simplest method IF the item can be completely submerged. Weaker 3% peroxide requires longer application time.

Hydrogen Peroxide Homemade GEL. This method has many names online: seaglow, sauce & retrobright. Recipes & more info available online. Honestly I dislike to complicated process.

Hydrogen Peroxide ready made GEL. This method is perfect for large items. The peroxide gel will stick to the plastic during application."Cream Peroxide 40Vol" 12% Strength. Its found in hair salon stores. Simple, cheap & works. Note: Some versions of Cream contain unwanted bleaching agents that can have unwanted effects on the plastic. Test your Cream before applying to your beloved item. I have also noticed the same issue with retrobright recipes.

Peroxide Treatment:
Use protective goggles and wear rubber gloves. Peroxide will irritate your skin and can cause blindness! Place the mixture away from children or pets! Be sure to remove all nonessential items from the plastic. This method is only suitable for previously white or light gray plastics. Colored plastics will have mixed results and damage the surface color. Never treat paper decals and delicate labels.

Ingredients for this Tutorial:
Hydrogen peroxide 12%. "Cream Peroxide 40Vol" Found at hair salon stores. No mixing or other ingredients needed. Once coated, seal the item in a large ziplock bag or large clear garbage bag. Sit the item outside in direct sunlight. After 3-4 hours the item should turn to its original color, rotate item every hour. Rinse and repeat until desired color is obtained. DO not allow the cream to dry! This will cause scars on the plastic surface. Avoid hot areas such as black asphalt.

Methods of Treatment: Go to this website for detail information. https://www.wikihow.com/Clean-Circuit-BoardsThe following information listed below is for review only.

Circuit boards can become notoriously dirty, accruing dust and whiskers from soldering. By using higher-grade alcohol, circuit board users can thoroughly clean and maintain a circuit board of any size in a few simple steps. Higher-grade (around 95 to 99 percent) isopropyl alcohol and ethyl alcohol are the most effective cleaning solvents.

On the other hand since isopropyl alcohol dries quickly, it is selected as preferred method to cleaning electronics. ... In these case also we can apply isopropyl alcohol as a cleaning agent.

How do you clean corroded circuit boards? - Insert a toothbrush into the baking soda paste and apply it onto the corroded parts of the circuit board. Scrub the circuit board gently with the toothbrush to loosen some of the corrosion.

https://www.techwalla.com/articles/how-to-clean-electronic-circuit-boards
https://www.wikihow.com/Clean-Circuit-Boards