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Why is your bathroom sink cracking?

by Badeloft | April 25, 2021

First, do not be alarmed, as many bathroom sinks crack. Lower quality materials such as fiberglass and porcelain are less durable and need to be handled with care to avoid cracking. So today we will discuss common reasons why your bathroom sink is cracking and how to repair it and ensure that it doesn’t happen again. 

Common bathroom sink cracking issues

It’s a fact that many bathroom sinks inevitably crack due to poor use with a more delicate material like porcelain. Here are some common reasons why your sink may be cracking. 


Extremely hot water in a cold sink

Like most things, sinks do not enjoy drastic temperature shifts. Extreme temperature changes, such as hot water in a cold sink or ice cold water in a hot sink can denature and change the physical aspect of the material. In the case of less durable materials such as porcelain, fiberglass, wood and glass, these materials will eventually break down and erode if exposed to drastic temperature shifts over long periods of time. These usually will manifest as cracks, material stripping or warping. 

Natural Hairline Cracks

Overtime, some sink materials can begin to age and crack. If not repaired and treated properly, natural cracks can result in even bigger cracks that can cause the deterioration of the sink itself. Natural hairline cracks are common in natural stone sinks as a result of the construction process which creates grains and points of weakness in the sink structure itself.  

Dropping heavy items

Most sink and bathtub materials on the market cannot sustain heavy impacts. They are made to resist and weather natural erosion, not blunt force. This statement rings true for common sink materials such as porcelain, fiberglass, acrylic, fireclay and glass. Copper, stone resin, stainless steel and quartz can weather heavy impacts, but you can easily scratch these materials, so avoid dropping heavy impacts on your sink. 


Many manufacturers use layers of steel to strengthen sinks constructed from weaker materials such as porcelain and fiberglass. While this does strengthen the structural integrity of the sink, the steel will eventually rust. Rust poses many problems as it is a result of the metal oxidizing with the air around it which causes it swell and place more strain on the supports of a structure. If not treated properly, any sink constructed from steel or other metals will cause hairline cracks in your sink’s structure. 

Avoiding Sink Cracks: How to care for your sink 

Now we’ve established the dangers to your sink, how do you protect it? Here are some ways you can safeguard against cracking and ensure that you do not have to deal with a larger headache in the future. 


Repair Sink Cracks ASAP

As we discussed previously, cracks in your sink can ultimately lead to larger cracks and eventually structural loss of your sink, ie, your sink breaking in half. To prevent this, it is important that you repair cracks as soon as you notice them. This can be done with either an epoxy, also known as plumbers putty which creates a watertight seal in the crack. Similarly, many professionals also use silicone caulk-both are acceptable options for repairing cracks.  

Daily Cleaning

To prevent cracks from forming in the first place, you should advocate daily cleaning of your sink. Although it may seem mundane, just a daily wash of debris and other elements can lead to better longevity for your sink. Excess moisture can lead to mildew, which can ultimately lead to the denature of the material, which will weaken the structural integrity, resulting in cracks. So, to preserve the quality of your sink, make sure to clean it regularly. 

Using Warm water vs hot

As expressed previously, avoid exposing your sink to extreme temperature shifts. Try to use warm water to gradually bring your sink to a higher temperature before switching to hot water. Or, if you see yourself using hot water quite frequently, consider purchasing a sink material such as copper or stone resin that can handle higher temperatures.

Following manufacturer instructions

All sink manufacturers will provide you with a list of do’s and don’ts. Similar to what we’ve stated before, this list will inform you about the material your sink is constructed from and what it can and cannot handle. Like in the case of porcelain, avoid high temperatures and heavy impacts on the sink to avoid cracks. Or in the case of natural stone, repair hairline cracks as soon as they are readily visible. Be sure to follow your manufacturer’s instructions so you can practice good habits with your sink to ensure it’s longevity. 

What if you cannot repair the sink?

Sometimes, even after a great deal of effort, your sink cannot be salvaged. Here are some things to consider when looking for a new sink to avoid the headache of your last sink.

Replace the old sink with a new sink 

Sometimes, it is much easier to replace your sink than attempt to repair it. This is especially true if the material is expensive or difficult to work with. Fiberglass and porcelain sinks are fairly inexpensive materials compared to other sink materials, which makes it more worthwhile to simply replace rather than attempt the repair. When replacing, focus on higher end material such as stone resin, copper, cast-iron or natural stone. A higher quality material will be much easier to use and can withstand a greater deal of abuse, saving you fewer trips to the store. 

  1. Different material-A different material affords you different benefits with your sink. Higher end material such as copper, cast-iron and stone resin affords you a higher heat retention, which means your sink can withstand and absorb higher temperatures and hold it for longer. They also can withstand blunt impacts better than cheaper materials and ultimately require less maintenance and cleaning. So while it may seem like these materials are much more expensive than a fiberglass or porcelain sink, they are much more cost-effective in the long run. 
  1. Different styleSinks are available in a large variety of styles which caters to a variety of lifestyle options. Wall mounted sinks are popular as they save a great deal of space without losing functionality. Then we have more simplistic designs such as a drop-in single vanity and basin styles which are ideal for smaller homes. And lastly, there is the freestanding sink which is ideal for all homes as it can be placed almost anywhere without being overly intrusive on space. Freestanding sinks are also popular as they are among the easiest to install and maintain with fewer drawbacks. 

Many bathroom fixtures such as sinks and bathtubs will eventually wear out with heavy use. To avoid the headache of having to repair your sink constantly, do the research and invest in a higher quality material for your bathroom. A better sink material will result in less cracks and fewer headaches for you down the road. 

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