This post has investigation report on probable cause of problem I witnessed in restaurants with sauce container. The report can be found here. Oracles and Heuristics used to learn probable cause of problem are:
- Tomato sauce container.
- Tomato sauce.
- Size of sauce container's knob.
- Air circulated around sauce container.
- Warm water.
- Allowing blocking contents to dry and time.
- Dried and wet sauce content.
