The short answer: perler beads are made of low-density polyethylene (LDPE), the same soft plastic used in squeeze bottles and plastic bags. It is chosen because it melts at a low, safe temperature around 130 degrees, which works well for craft irons.
Knowing the plastic helps you understand safety, melting behavior, and how to fix mistakes. Here is what the material means in practice.
Why LDPE?
LDPE melts at a lower temperature than many other plastics, so a regular household iron fuses beads without getting dangerously hot. It also stays soft after melting, which makes finished pieces slightly flexible and less likely to shatter if dropped. The same material is used for food containers, which is why perler beads are generally considered low-risk around children, though they are not food.
Brand differences
Perler, Hama, and Artkal all use polyethylene, but the exact formula differs. Some generic brands use softer blends that melt faster and make the holes close up sooner. That is why ironing times vary between brands, and why mixing brands in one piece can produce uneven melting. Our Perler vs Hama comparison looks at these differences. For a safe melt every time, follow the settings in our ironing guide, and test unknown beads on a small piece first.