What material are old tailpieces and traps often made of that can easily break with a gentle touch?

The material commonly used in older tailpieces and traps that can easily break with a gentle touch is lead. Lead has been used in plumbing applications for many years due to its malleability and resistance to corrosion. However, over time, lead plumbing materials can become brittle, especially if they are exposed to moisture or environmental stressors. This brittleness can make lead pipes and fittings susceptible to cracking or breaking with minimal force.

While soft brass, cast iron, and polyvinyl chloride (PVC) have their own characteristics and applications, they do not typically exhibit the same degree of fragility as lead does, especially in aging plumbing systems. Soft brass can be somewhat resilient, cast iron is usually quite sturdy, and PVC is known for its flexibility and durability. Thus, lead is the material that stands out as being particularly prone to breaking with a gentle touch in older plumbing systems.