Why Do Slow Cookers Crack? (Plus Some Safety Tips!)

I love my slow cookers. I’ve used them hundreds of times and sometimes left them on overnight or while I was at work. But lately, I’ve heard concerns about them cracking. So I decided to investigate why do slow cookers crack.

Here’s what I found out:

Slow cookers will only crack under 3 circumstances: 1. They will crack due to quick drastic temperature changes, using it on a stovetop burner, or setting it down too hard on the counter.

But there’s a lot more to dig into, so let’s keep looking at some of the top related questions.

If you’re looking to buy any small kitchen appliance, don’t forget to check out my Recommended Products Page (click to see my page) which breaks down all my best picks by category.

I always hand-select items that I either own, have used, or have researched well to ensure they are great items. I also give not only top of the line as well as inexpensive alternatives so my choices work for any budget.

What are the top causes of slow cookers cracking?

Here are the number one reasons why slow cookers crack:

  • Drastic temperature changes, such as having had the ceramic insert in the refrigerator all night and then placing it right in the shell to heat up.
  • Placing a large completely frozen item in the Crock-Pot and heating
  • Submerging a hot ceramic insert into cold water
  • Using the ceramic insert directly on a stovetop burner
  • Setting the ceramic insert down too hard in the sink or on a counter and creating a small crack that will later expand when heated

But cracking is most likely to occur when you place a hot slow cooker into cold water.

For instance sometimes after we’ve plated the food from the Crock-Pot, it’s tempting to stick the insert right into the sink and fill it with water to soak.

Doing that while the ceramic insert is still hot, could definitely cause your slow cooker to crack if the water was cold enough.

Setting the ceramic insert down on a hard surface with too much force could also cause cracks. In some cases, those cracks might be microscopic but the next time the slow cooker is heated, it could cause the cracks to break apart.

Crock-Pot themselves recommend to always fill your slow cooker at least 1/3 of the way full.

Also, without at least some liquid in your slow cooker, you risk scorching (ie: burning) your food. And also drying it out unless the food has high moisture and/or fat content already.

But if left on for too long, there’s also a slight possibility of cracking.

Lastly, if the ceramic insert from your slow cooker is in the refrigerator with leftovers you want to warm up, make sure it comes to room temperature before any reheating.

Do this by setting it on a kitchen counter until it no longer feels cold.

Can you fix a cracked Crock-Pot or slow cooker?

No, you cannot repair a cracked or broken Crock-Pot ceramic insert. If the outer piece is in good condition, you can, however, order a replacement insert. But you may find it’s not any costlier to just buy a new one.

You could superglue the crack. However, its food safety would certainly be questionable. Plus, the fix might not hold up to the heat over time.

Plus as inexpensive as slow cookers are these days, why bother with trying to fix a cracked Crock-Pot?

Is it safe to leave the slow cooker on overnight?

Yes. It’s perfectly safe to leave your slow cooker turned on overnight. Slow cookers are actually designed to be left on for long periods of time.

Most Crock-Pot owners aren’t entirely certain how to use them. They also wonder if it’s safe to leave a slow cooker cooking all night.

Fear not!

But leaving them on all night doesn’t mean the wrong combination of ingredients might not scorch on the bottom. It also doesn’t mean that if you add too much liquid it won’t splatter on your counter.

But as a general rule, it’s totally fine to leave your slow cooker going all night while you sleep. Just keep it at least 6″ away from the walls and make sure the cord is not near the sink or any liquids.

For splatter reasons, I LOVE my Crock-Pot with a locking lid (click to see the one I bought on Amazon)! No more mess on the counter when I wake up or come home from work.

Is it safe to leave a slow cooker on while at work?

Yes, it’s totally fine to leave your slow cooker on all day while you are at work or otherwise out of the house. Ideally, set it to low which is most typically the setting you would use for 8 or more hours.

Also, make sure your Crock-Pot is on a heat-proof surface like granite countertops.

Lastly, make sure the slow cooker is on a totally flat surface. Tile countertops can sometimes be bumpy and you don’t want to risk it tipping over and cracking or spilling. This is especially true if you have cats that like to jump on countertops.

Some slow cookers allow you to seal the lid closed which helps prevent a mess.

Want further confirmation about their safety?

On Crock-Pot’s FAQ page they state “Crock-Pot® Slow Cookers are safe for countertop cooking for extended periods of time. If holding food on the warm setting for a long time, cut back on the cook time accordingly to reduce overcooking.”

Can I leave a slow cooker on warm all day?

No. You should not leave uncooked food, especially raw meat or seafood, on warm all day in a slow cooker. The warm setting on most Crock-Pots and other brands of slow cookers is designed to hold the temperature, but it’s not meant to heat up food or cook raw food.

So just make sure your food is thoroughly cooked (especially important for meats and poultry). THEN you can leave it on warm all day.

So, for instance, if you cooked a brisket all night and want to have it for dinner, you can set it to warm before you leave for work.

Just make sure to add plenty of sauce to it, and it should hold temp just fine all day.

Can you put a Pyrex dish in a slow cooker?

Yes. You can place a smaller oven-safe Pyrex dish inside the ceramic insert of your slow cooker. You do not need to use the lid for the Pyrex dish but do still use the slow cooker’s lid.

Stephanie O’Dea, New York Times best-selling slow-cooker cookbook author confirms it.

Simply put your ingredients into a small oven-safe glass baking or Pyrex-style container and set that inside the slow cooker.

Can you put a slow cooker dish in the oven?

Yes. Virtually all brands of slow cookers are oven-safe up to 400°F, as well as microwave, and dishwasher safe. Do not, however, use them on a stovetop or over an open flame of any kind.

Heating a slow cooker on a stovetop could definitely be another reason slow cookers crack.

As always though, since there are so many different brands of slow cookers, it doesn’t hurt to verify with your manufacturer.

Are slow cookers toxic?

No. Current model slow cookers are not toxic. A 2004 study found that 20% of slow cookers were leaching small amounts of lead into the food cooked in them. However, leaded glaze was commonly used at that time and is not commonly used now.

The concern with slow cookers and toxicity comes from a 2004 investigation by Bill Gebhardt of Salt Lake City’s KUTV.

He was investigating possible lead exposure by lead leaching into the food as the Crock-Pots got hot. He found that about 20% of slow cookers were leaching small amounts of lead into the food cooked in them.

In general, when ceramic containers are heated to 80°, they release 10 times the amount of lead than they do unheated. Since slow cookers heat over 250° he felt it was worth investigating. Acidic foods tend to release more lead when heated as well.

Of course now, over 15 years later, virtually all brands of slow cookers state that their products do not contain leaded glaze. They also state that their slow cooker is in accordance with the FDA Compliance Policy (which states that leach levels of 1 mcg/mL are acceptable).

Luckily the FDA maintains a list of products that have tested positive for lead and there are NO slow cookers on that list.

Can slow cookers catch fire?

No, a slow cooker is not likely to catch fire. At least not if the slow cooker in good working condition. But, almost anything that plugs into a wall could catch fire. So always replace the slow cooker’s power cord anytime you see it worn, cracked, or broken.

 After all, we are pulling electricity through a wire and into an item. The plug could be faulty, the wire could be faulty, or the appliance could be faulty.

That being said, if your slow cooker is in perfect working order, with no broken switches or frayed cords, you should be just fine.

Did I cover everything you wanted to know about do slow cookers crack?

In this article, we took a look at the concern lots of Crock-Pot lovers have over safety.

We examined the truths, lies, and myths that float around the internet about slow cookers catching on fire, rumors about toxicity and if there is lead in Crock-Pots. But we also answered some basic safety questions like whether you can leave a slow cooker on while you sleep or go to work.

Ultimately, though, we answered the question do slow cookers crack, and we explored exactly what might make them do that so you and your family can be safe and still take advantage of these awesome small kitchen appliances!

What’s your favorite slow cooker recipe?

If you’re looking to buy any small kitchen appliance, don’t forget to check out my Recommended Products Page (click to see my page) which breaks down all my best picks by category.

I always hand select items that I either own, have used, or have researched well to ensure they are great items. I also give not only top of the line as well as inexpensive alternatives so my choices work for any budget.


Photo credits:

Beef stew in the slow cooker by Ruth Hartnup is licensed by CC2.0

Jeff Campbell

Jeff was a leader for Whole Foods Market for over 2 decades and is now a recovering foodie. When he's not spending time in the kitchen, he can usually be found with his wife & 3 daughters, he can usually be found practicing martial arts, making music, or blogging on his other sites. Click to learn more about me

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