STTP is used as a food preservative. And surprisingly it is considered about as toxic as salt, vinegar or baking soda. The worst part of it is it can be an irritant if it gets in your eyes.
We did our test last night with STTP and Palmolive Lavender Non Phosphated Gel. Perfect results. We used 1 tsp STTP mixed in with the gel. The load was unrinsed plates & bowls from a scrambled egg/hash brown breakfast that had been sitting for at least 14 hours before washing. While this gel will clean the plates and glasses well, it leaves food on the pan it was cooked in and hardly touches the spatula we used. With STTP everything came out clean.
So tonight I will test with only 1/2 tsp of STTP and see if the results vary.