How to Tell if Your Tub Is Cast Iron

Bathtubs come in a number of different materials.

What kind of tub is it?What kind of tub is it?
From lightweight fiberglass tubs to heavy cast iron to stainless steel, tubs are made out of materials that are very different to remove and to clean. Older cast iron tubs with claw feet can be coveted collectors' items. Cast iron is very difficult to move, so if you are changing a tub, you will need several people to help. Acrylic tubs, on the other hand, can be taken apart very easily.
Cast iron objects make a deep sound when you hit them.

Tap on the tub. Does it sound like it is solid or hollow? An acrylic tub is light and will sound hollow inside, like you are knocking on a door. A stainless steel tub will make a ticking or clacking sound. A cast iron tub will sound like a deep gong, just as if you hit a cast iron frying pan.

Steel looks metallic or is covered with a layer of paint, while cast iron is often black.

Look at the bottom of the tub if possible. A cast iron tub will be black, and a steel tub will be metallic, although it may be covered with a layer of paint. An acrylic tub will look like coated plastic.

A cast iron tub is usually over 300 lbs.

Try to lift the tub. If you are removing the tub, it is easy to tell if it is cast iron. A cast iron tub is at least four times heavier than a steel tub.

Housing complexes often have records of the original installation of materials.

Ask your neighbors and the people who owned the house before you. If you live in a housing complex where all the houses are similar, there may be records that state what tubs were installed in the complex. If you are just moving into a house, ask the previous owners who installed the tub and when, and ask them what the tub is made of.

Things You Will Need

  • Bathtub

About the Author

Anise Hunter began writing in 2005, focusing on the environment, gardening, education and parenting. She has published in print and online for "Green Teacher," Justmeans and Neutral Existence. Hunter has a Bachelor of Arts in English from the University of British Columbia and a Master of Resource Management in environmental science from Simon Fraser University.