Disclaimer: Ink&Iron takes no responsibility for injuries incurred by viewers of this video for attempting the techniques demonstrated herein. You are accountable if you choose to repeat this demonstration yourself.
Joe shows a tip that should work for most plastic keyboards to fix yellowing with readily available chemicals and sunlight. This example shows a typewriter keyboard but computer discolored computer keyboards should also be fixed with this technique. After using both liquid peroxide and salon creme, this channel recommends the creme.