This is an incredible product. I bought it a while ago but just tried it out today. I heated water to prime the thermos to be cleaned and poured out the water. I then heated water again and poured it in the 64 oz thermos. I put 4 tsp of smartsoak in initially but some of this bubbled off so I added two more teaspoons. In only seconds I could see my tea stained thermos interior was white colored again. I let it soak for twenty minutes as suggested. I then decided to try the same solution on a glazed teapot and strainer. I let that soak for 30 minutes. It did a pretty good job on this reusing the solution, making it sparkle too. The only thing it did not do was get all the tiny bits of encrusted tea off the strainer. It did make it sparkle though. I am glad I bought the large size of this and will definitely buy more when I run out. This stuff is worth every penny it costs.