I appreciate analogies when I start learning something. Although it's not a perfect representation of what's being taught, it makes it easier for me to start thinking about the topic I'm learning. I can fill in the details later. I think it's useful for certain types of learners such as myself. Although I'm not deeply familiar with the characteristics of construction materials, I was more familiar with them compared to types when I was learning about them. So it would've been a helpful analogy for someone like me.
Personally, I avoid analogies because they usually mean I don’t really know how to teach the topic, and I’m “hand-waving” on the fly. I either find a way to build on the student’s existing knowledge or I “park” the topic for discussion when the student has enough knowledge to give a correct answer.