How can you determine when molten lead is ready to pour if you do not have a thermometer?

To assess the readiness of molten lead for pouring without the use of a thermometer, observing a bluish tinge is crucial. As lead melts, it will take on a shiny, silvery appearance, but as it reaches a temperature suitable for pouring, it develops a characteristic bluish hue. This color change indicates that the metal's temperature has reached an optimal state for casting without being too hot, which can cause issues like overheating and oxidation.

The other options do not indicate the correct readiness of molten lead. If it were to become solid, it would obviously no longer be in a state suitable for pouring. Bubbling can suggest that the metal is still heating or may contain moisture or impurities, which is not ideal for pouring. Emitting a strong odor can indicate overheating or the presence of contaminants, which can compromise the quality of the poured lead. Thus, recognizing the bluish tinge is the most reliable visual cue for determining the appropriate pouring temperature.