Originally Posted by
tessagin
I used to be a Tupperware agent. I still have a few and I have the cereal containers. I wash mine often but never in the dishwasher no matter what. Whatever piece you have seal or container on the bottom should be a number. The pieces may be free but yes you have to pay for shipping. I just had a seal replaced the other day. I also do not put them in the microwave. I have gotten to where I only use paper plates (not foam) or corning ware or regular cereal bowls or cups in the microwave. Nothing plastic or foam. Those seam in bags of frozen veggies get emptied and put into a regular cooking micro wave safe cookware.
Tupperware became "dishwasher safe" sometime early in the 1980's. The seals before that have a really smooth surface; after that, the seals had a little bit of texture on the surface. That's how you can tell the difference. The smooth ones should not go into the dishwasher. They will warp.
The only Tupperware I put into the microwave are the ones made for the microwave: the ones with the vent in the seal. I use them all the time in the microwave. They are my go-to for leftovers.