I used to be a Tupperware dealer and Manager years ago and they are well aware of the problem. The only thing that ever worked for me to any degree was baking soda. Add just a tiny amt. of water to make it into a thick paste and then scour like mad. You can also try toothpaste, but that’s more expensive to use a lot of than baking soda is.. Anything stronger than these like Ajax or Bon Ami will just make everything worse as it just abrades it too much.
But, the key here may be that it’s been microwaved and therefore embedded into the plastic. There is no way to get that out because it means that the plastic melted or softened enough to basically fuse with the sauce; not a pleasant thought.
However, there is a possibility that you may have another option to just throwing it out. You can just throw it back to the company and get shiny new back at no cost to you. This is the silver lining for you which is the bane of every dealer’s existence.
Tupperware carries with it a lifetime guarantee regardless of circumstance which every dealer is supposed to honor. This has been from the inception of the company which added much to their reputation and somewhat justified the much higher cost compared to other plastic products. In my time I replaced product which had been left on an electic burner and melted beyond recognition to stuff impaled by a carelessly wielded knife to stuff which had been frozen and shattered when dropped. You name it, I saw it.
and they don’t seem to be touting it as much now. Admittedly, when I worked for them it was many years ago , but afaik they have not changed their policy. Since swapping out damaged product and replacing it with free new stuff is not exactly a delightful adventure for your average hardworking Tware rep. they may tell you something like they can’t do it cuz it was microed to death, or whatever excuse springs to mind so you def. need to check with the company first about what is entailed in the lifetime guarantee. It’s worth a phone call to their 800 line to get the facts and proceed accordingly.
Hopefully the guarantee remains the same as those halcyon days of yore and you will soon have sparkling shiny new Tware replacing all those red stained ones.
Here’s a little word to the wise—instead of putting spag sauce in Tware, plastics have improved tremendously in recent times. Get thee to the supermarket and get the new hard, clear plastics from Rubbermaid which will not stain. It’s a totally different type of plastic and it really is impervious to stains. I have tried it and it’s great. Use your Tware for anything else.
And whatever else you do, stop microwaving food in plastic containers for the sake of your family’s health not the health of the Tware. Some rudimentary research should convince you of the dangers inherent in ingesting the toxins which leech out of melted plastic.
I just run the plastic cont. under hot water for a few moments so I can dump it into a glass or ceramic dish—only takes a few seconds.