Which soldering issue may arise from too little heat applied during the process?

When insufficient heat is applied during the soldering process, one of the primary issues that can arise is the presence of bare spots. This occurs because the solder may not melt properly or flow adequately into the joint. For solder to create a reliable bond, it must reach the correct melting point and fully penetrate the joint surfaces. If the temperature is too low, the solder will not properly coalesce with the metal surfaces, leading to gaps where the solder fails to adhere. These gaps, or bare spots, can result in weak connections that may not hold up under pressure or stress.

In contrast, cracking may be more related to other factors, such as rapid cooling or incorrect alignment, whereas overheating relates to excessive heat that often leads to damage rather than inadequate heating. Excessive flux does not directly result from temperature issues but rather from improper application of soldering materials. Understanding the nuances of heat application in soldering is essential for ensuring strong, reliable joints in pipe fittings.