Does Iron Float in Water?

Iron like many other metals, including Gold, tungsten, lead, etc., does not float in water. You ever wondered how ships float in water when iron sinks in water? To understand this, you can know a little about the concept of buoyancy. Buoyancy is a force with which a fluid pushes a foreign object upwards. This buoyancy or the upthrust should be greater than the force of gravity acting on the object to make it float.

Why doesn’t iron float in water?

Iron doesn’t float because it is heavier than water. More specifically, it doesn’t float because it has a greater density, 7.87 gm/cm3, which means that each cubic centimeter of Iron (1 g/cm^3) will displace more than one cubic centimeter of water (1 g/cm^3). In simpler words, approximately 8 grams of water will be replaced by 1 gram of Iron. When you put an object made of iron in water, water pushes it with much greater force than the object’s weight and thus enables it to float.

Why does an iron ship float in water?

Well, it certainly feels unjust that weighing tons, ships still manage to stay afloat, whereas small pieces of iron are never to be seen again. An iron ship floats in water because it has a lower average density than the surrounding fluid. The buoyancy of any material is equal to its average density-weighted by its sphere-of-fluid volume ratio. Ships have a compartment filled with air which makes their average density lower than that of water. Basically, they are empty vessels.

When an object is floating, or literally “resting on” the surface at its natural buoyancy, this means that an upthrust force is acting on it. That force is caused by either artificial inflation or displacement of water below the vessel keeps it from being pulled out of the area by gravity. Many iron ships also have a double bottom, which can weigh quite a lot and then needs to be balanced with air to be appropriately weighed down so that it has enough weight to stay submerged.

How can I make iron float in water? 

Considering that you have understood the concept of buoyancy, making anything with higher density float in water or any fluid having lower density should be a piece of cake for you. However, here are a few ways you can do that.

Hollow Iron Ball:

It works pretty much on the sample principle as a ship, as we explained earlier. All you need to do is make a hollow iron ball with a large surface area as a smaller ball will not float. It’s also essential to keep the walls of the ball as thin as possible, so it does not have more mass than the water it is supposed to displace. Furthermore, it is crucial to check for any leaks or holes in your ball. If there are, water can fill up, which will make it sink. The air inside the ball makes the average density of the ball (iron + air) lesser than that of water, making it float just like any air-filled object.

Another way you can make an iron ball float is by filling your ball with polyester resin. Fill until the weight at which it starts to float becomes apparent – that’s when you should stop filling them with resin, or else they won’t sink at all once placed on water.

Iron Foil:

If nothing else, you can always rely upon iron foil to float in water but with certain restrictions.

  1. Start by cutting up a sheet of iron foil, so that you have several small sheets.
  2. Place one of these small pieces of foil on the water with an index card sticking out to the side.
  3. When you remove the index card, instead of seeing just one sheet of foil on top of the water, you will see two smaller pieces huddled together. This is because metal and most substances are denser than water and sink to the bottom. The air bubbles trapped in between the sheets serve as a barrier against this surface tension behavior which holds both pieces up on top above them where they are easier to grab if need be.
  4. If too many bubbles leak or dissipate from between two sheets, they’ll sink.

Wrap It With Something Lighter:

The iron itself is approximately eight times denser than water and sinks to the bottom rapidly. However, if you wrap it in something lighter or less dense than water, it will float.


You can always try making a thin layer of oil on your piece of Iron. Although, keep in mind that this only works on thin and lightweight pieces of iron and will not work on small and solid pieces.

Styrofoam and Thermocol: 

These are made of styrene and polystyrene. You can try placing the iron on a block or sheet of either of these materials, and it will float given it is not heavy enough.

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