My solution I call: D'ultimate
FIRST just rinse off the figure. Then use dish soap which has a degreaser and just smother the item/figure/etc. Let it sit then use slightly warmish water and tooth brush to scrub it all down. This will get the grime off.
SECOND when you have few ready/done put them in clear glass container and add dish soap, laundy detergent, (salt if REALLY disgusting), hydrogen peroxide and finally the "secret ingredient" OXY CLEAN (use quite a bit). When you have a reasonable little pool of this crazy sludge on bottom your good.
THIRDLY you run hot water from fauset and add JUST A BIT to container to "activate" and close lid. Shake the heck out of the container until it is thinned out. Now let it sit like 4-5 mins. Shaking a few times. Once temp on container has cooled down (not cold) open it back up and slowly fill the remainder of the container with warm-ish water. Once full ur good. Seal it back up and give it a few light clockwise/counter clockwise shakes to help contents settle.
FOURTHLY, and most important step: Place glass container directly in the sun... A location where it will always be getting rays. A window ceil for instance. For the super adamant, place it directly outside during the daytime. This step can last days or weeks depending on your desirability or the condition you wish to achieve. More yellow = More time etc. Now remember to at least a few times a day to shake the container to both let the solution NOT settle but also to move the objects inside around for maximum exposure/treatment. Open and move/re-shuffle items when necessary, but always keep the lid closed for treatment sake.
FINALLY, Once you have noticed the desired amount. Simply open and pull out items "ready" for final rinse. Lay items out and let them dry, after enough time Use the toothbrush and running water (slightly warm) to clean off the solution. This can take a few times to make sure its off (and out... Aka the inside too) of item. It will look brighter than ever, but yes... Keep rinsing it until you know its (the solution) is really gone from the item. I mean really "go to town" over and over since you want none of that left. Period.
Just let items/figures/etc. Air dry and afterwards you'll notice not only the brightest finish but will be really nice clean smelling!
Now WORD of caution: Not all plastics are the same exact materials so some can... And will often change color... As In a NEW color. So always keep an eye out. Its like how you don't want to over cook food (whatcha think the sun was for 😉) BUT as a customizer I've found this is a fantastic way to get new original parts, you can even use dyes in the mixture or left-over solution to take it even further. Example: Black RIT DYE will give you the nicest shades of blue or purple-ish to the various types of plastics. I personally love doing this with figures that kids have "customized" with pens and markers on clone troopers etc. the stuff that won't come off becomes part of the design adding new color variations and markings with the solution/dye. Afterwards just make sure you really OVER wash the parts since you don't want dye leaking/dripping out or rubbing off. This can sometimes take many rise/dry attempts.
Have fun my friends.
