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How to Tell What Your Bathtub is Made of? – Pro Tips!

how to tell what your bathtub is made of
Written by Elizabeth Fincher
Last Update: August 10, 2023

You’ve just bought your new house but after checking out the bathtub, you’re not sure what it’s made of! How would you be able to take good care of it if you don’t know the material in the first place!

So, if you’re wondering how to tell what your bathtub is made of, here’s what to keep in mind –

  • If you think that yours is an acrylic or fiberglass bathtub, put pressure on the side of the tub and it will have a bit of giving. If not, it may be something else. Cracks and scratches on your tub indicate acrylic and fiberglass
  • If you hard press on your bathtub and it shows completely no response, perhaps your tub is constructed or coated with enamel steel or other metal substance
  • Porcelain-coated tubs don’t necessarily crack but are prone to chipping if heavily hit. A rusty tub is a sign of metal
  • Cast-iron and steel tubs will respond to a magnet. Most claw foot bathtubs you see are made of cast iron
  • Inspect the flooring of your tub if there is any second flooring support to hold the weight of your bathtub. Heavier tubs like porcelain or cast iron need extra support when acrylic or fiberglass don’t, as they are lighter in weight

Why Does the Tub Composition Matter?

When you know what material your bathtub is made of, you have clear ideas about the amount of weight your floor carries, or how you would deal with your bathroom renovations.

You would understand how long your bathtub may last and if it is good or bad for your choice and overall health.

How Bathtub Materials Affect Refinishing

No matter what material your tub is, you can get it refinished. But the material impacts the refinishing procedure.

Special tools and chemicals are used to repair cracks and chips before the enamel coating comes in. Some tubs take longer to refinish than others depending on the material they were made from.

Most Durable Bathtub Materials

Pure cast iron, copper, and enamel steel are considered the most durable bathtub materials.

Since many users have faced rust issues with cast iron tubs, consider choosing copper as the best choice of material to take your bath in.

How to Tell What Your Bathtub is Made of?

1. Fiberglass (FRP) Bathtub

A fiberglass bathtub would be thicker and have thin edges. They come in different shapes and styles. Most of these bathtubs are white and lightweight.

A regular fiberglass tub weighs around 70-80 pounds. They are usually flexible and flimsy but appear modern in looks.

Fiberglass tubs have 10-15 years of lifespan. Lower price and easy reparability make the fiberglass-made bathtubs a popular choice.

2. Porcelain Bathtub

Porcelain bathtubs are built from a base of iron, steel, tile, and glass. Then they are coated with porcelain enamel steel which makes them, extremely resilient and easy to clean.

On the downside, they are heavier than acrylic or fiberglass bathtubs and their exteriors are likely to rust over time.

3. Acrylic Bathtub

Acrylic tubs are built of vacuum-formed acrylic sheets, fiberglass insulation layers, and fiberboards. Acrylic is a soft and supple material, perfect for creating a diverse range of shapes and sizes.

You can bed in the acrylic bathtubs on every level of your house as they are super light and easily repairable. Acrylic bathtubs cost a little more than fiberglass tubs.

4. Ceramic Bathtub

Ceramic bathtubs are classics that are still popular in modern days. Plenty of ceramic tiles is put together to form them. They are a special kind of clay that is hardened with high heat.

They are found in numerous shapes as they are easily molded and cost relatively less.

5. Stone Resin Bathtub

To construct a stone resin tub, the actual natural stones are crumpled and crushed and then they are bound together with the use of polymer resin and a few other minerals.

Water cannot discolor these tubs and they are coated with a glossy gel layer. You’ll find countless shapes, colors, and designs for these expensive tubs.

6. Cast Iron Bathtub

The enameled cast-iron bathtub is another classic and is known for durability and heaviness. They are molded iron with porcelain enamel coating. If maintained well, a cast-iron tub is an investment that will serve you for a long time.

It may require the structural reinforcement of the floorboards as you install the cast-iron bathtub because of its heaviness.

7. Cast Polymer (Cultured Marble, Granite, or Onyx) Bathtub

Cast polymer bathtubs are built with engineered natural rocks and dense surface materials.

Polymeric substances, minerals, and resins are mixed to produce a Corian-like hard material and then coated with gel to finish off.

They are affordable tubs with various color options. These cultured marbles are stain-resistant and easy to clean.

On the downside, they are brittle and the gel coat gets weary with time which may lead to unrepairable cracks

8. Copper Bathtub

Bathtubs that are made of copper are highly durable and antibacterial. Generally, they are not mass-produced, they’re custom-made to fit your desired shape.

Copper bathtubs are special, they are eco-friendly, mold-resistant, hold up maximum heat, and last a lifetime.

A copper bathtub promotes surprising health benefits and contains natural antiseptic properties. It will remain hygienic and provide you with a healthier and safer bath each time.

9. Wooden Bathtub

Wooden bathtubs are innumerable pieces of wood glued together in the shape of bathtubs. Like copper bathtubs, modern wooden tubs are not mass-produced but are custom-made.

Wood is an ancient organic construction material, but the wooden bathtubs of today are nothing like from the middle ages.

These are some of the most high-priced bathtubs on the market as they are handmade pieces of art that resemble luxury.

10. Metal Bathtub

Mix metal bathtubs are strong, sustainable, and heavy. They are a great family choice and can endure the test of time.

Metal bathtubs keep your water warm and hygienic for longer and they are comparatively easier to clean.

On the negative side, these tubs are cold to touch in the first place and call for a strong base. Metal tubs may get chipped if something heavy falls onto them.

11. Plastic Bathtub

Plastic bathtubs are the cheapest on the market but you will find the most options and variants with them. They are available in every color, style, shape, and size you may think of.

Though plastic bathtubs don’t hold up over the long term, they are easy to carry and great for bathing outdoors. Plastic tubs also come in handy for your beloved children or pets.

12 Proprietary composites

Proprietary-composites consist of porcelain enamel, heavy gauge steel, and resins, which make a tub that has all the advantages of cast iron but weighs almost half. They are a relatively new type of bathtub on the market.


1. How can I tell the difference between cast iron and cast steel?

Ans: Cast iron has more vibration damping properties than Cast steel. Cast iron is brittle and cast steel is ductile. Cast iron has weaker machinability and weldability than cast steel.

2. How can I tell if it’s brass or bronze?

Ans: You can easily differentiate brass and bronze by their color. Brass resembles dim gold, like a muted shade of yellow. And bronze has a darker shade, like the reddish-brown.

3. Do steel bathtubs rust? 

Ans: Yes, steel and iron bathtubs eventually rust due to their inevitable exposure to water. But you’ll have the option at hand to refinish or recoat them once they get a little rusty.

4. How do I know if I have fiberglass or plastic?

Ans: Plastic and fiberglass are confusing because they have the same look. The major difference between them is plastic is organic whereas fiberglass is inorganic.

About the author

Elizabeth Fincher

Elizabeth started her career as an interior design artist at a multinational interior design farm. She completed her masters degree from the University of North Texas back in 2010. She was also a Spelling Bee runner-up when she was 14. She took interest in bathroom interior designing after joining her first job. Later she started her own firm as an independent artist. She’s been one of the founding members of Toiletsguide. She examines the design and ergonomics of the units we review and directs the interior decoration team of our in-house research facility. Elizabeth plays piano masterfully and always finds time to entertain us in between our busy schedules.

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