Are Mason Jars Dishwasher-Safe and Are They Clean When You Buy Them

Mason jars are vital for home canning and food preservation. People use them for decades to preserve fruits and veggies. These jars have grown in popularity since people learn more about the dangers of storing food and homemade beverages in plastic containers.

Mason jars are also great for storing dry goods to keep them protected and fresh. They help you to be more organized (you can easily see what’s inside) and keep your pantry clean and tidy.

Mason jars are composed of a glass jar and a screw-type silver lid that creates a tight seal.

Newbies to preserving food in mason jars commonly look for instructions on the internet to be sure that everything is done properly. Here are some of the most common questions asked by people who are new to home canning and preserving food.

mixed vegetables in mason jars

1. Are Mason Jars Clean when You Buy them, or You Must Wash them Before First Use?

When you buy new jars, they are not sterile, no matter how well packed. The jars can be contaminated with dust and debris and may even contain pieces of broken glass. That is why you must clean the jars before using them for storing food. Sometimes the jars require sterilization to remove any contamination by microorganisms and prevent food from spoiling.

You can sterilize the jars in the dishwasher by selecting the sanitize cycle or you can boil them in water.

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Can Mason Jars Go in the Dishwasher?     

This is one of the most frequently asked questions about mason jars. Yes, mason jars are dishwasher-safe. These jars are made of glass that is safe to wash in the machine. Don’t forget to remove the lids before putting the jars in the dishwasher. Avoid overloading the dishwasher to allow water to circulate. Once the cycle is over, remove the jars from the dishwasher and allow them to dry completely before storing.

Mason jars are easy to clean by hand, much easier than plastic storage containers which may be stained if you freeze liquids in them. Wide-mouth jars allow you to reach the bottom with a sponge easily. For regular mouth jars use a bottle brush or canning jar cleaning brush to properly clean it.

To remove hard water stains from the glass, soak the jars for a few hours in a vinegar solution (1 gallon of water and 1 cup of white vinegar). Scrub the glass surfaces with a sponge and rinse well.

While glass jars are dishwasher safe, you might want to wash traditional metal lids by hand. Harsh dishwasher detergents and the heat of a drying cycle can wear down rubber seals on the lids.  If you wash the lids in the dishwasher place them in the kitchen utensil rack and use mild detergents.

Since lids can be made from other types of materials like plastic, wood, and silicone it is important to read the manufacturer’s instructions to make sure it is safe to put them in the dishwasher. Plastic and wood lids don’t rust which is a plus, but they are not as airtight as regular mason jar lids.

How to Clean Mason Jar Lids?

Before the first use, make sure to wash the lids with warm soapy water. Rinse the lids well and allow them to dry completely. Avoid machine washing as a dishwashing cycle may damage the rubber seal.

To remove rust from the lids, use a cloth soaked in white vinegar. Rub the rusted area with the cloth until the rust is gone. Hand dry the lids well immediately after washing, because water trapped inside the lids may cause them to rust.

Used lids often retain the smell of food that was in the jar. To reuse the same lid, you need to get rid of unwanted smells. One easy way to eliminate any trace of odor is to use baking soda and vinegar. Sprinkle baking soda into the lid and pour vinegar over it.  Leave the lids with this foaming mixture in for a few hours and then wash them off.

You can purchase new mason jar lids separately for an affordable price.

How to Pre-Sterilize Mason Jars? 

If you are processing your food for less than 10 minutes, you need to pre-sterilize empty jars to prevent contaminants from getting into your food.

Take a jar with a tong and submerse it in a large pot or canner filled with water. Ensure that the jars are filled and completely covered with water. Bring the water to a boil and leave the jars in boiling water for 10 minutes. Then turn off the heat and leave the jars in hot water for an hour.

Grasp the jars with a tong and empty the water. Place the jars on a clean surface to let them dry.

To sterilize the lids put them in a small pot with hot (not boiling) water and let them stay immersed in simmering water for at least ten minutes. Boiling water can harm the rubber sealing rings on the lids. Use a tong to take the lids out of the pot and place them on a clean surface to air dry.

Pre-sterilization is not necessary if you are going to process the food for more than 10 minutes because the jars will be sterilized during processing.

Are Mason Jars Microwave-Safe?      

Generally, mason jars are not microwave-safe. However, Ball mason jars have a microwave-safe symbol on them. But caution is still necessary because these jars are made of glass that is not reinforced to withstand temperature fluctuations. So, use them in the microwave for a small amount of time (up to 5 minutes). If you microwave them for longer than five minutes, the heat can cause the jar to expand and crack. Don’t forget to take the metal lid off before putting the jar in the microwave because metal parts are not microwaveable.

Are Mason Jars Oven-Proof?    

Mason jars are made of soda-lime glass which is not treated to withstand extreme high temperatures and sudden temperature changes. Mason jars can withstand temperatures up to 392F but must be heated gradually to avoid shattering. You shouldn’t use those jars as bakeware. If you put the jar in the oven to bake desserts and treats, high oven temperature can cause the glass to explode.

Another problem is that is not possible to achieve even heat distribution through the jar. The sides of the jar may get too hot while the middle of the jar fails to heat up.

Can You Put Mason Jars in the Freezer?             

Mason jars can withstand low temperatures, but it is important to take some precautions before putting them filled with food in the freezer. Frozen food increases volume, so the jars mustn’t be filled to the top. If you decide to freeze home-prepped soup, leave some space so that the content in the jar can expand without causing the glass to crack. If you fill the jar to the top and screw on the lid, the soup can push against the jar and crack the glass.

How to Store Empty Mason Jars?     

It is important to dry the jars and lids well before storage. Do not place the lids on the jar but keep them separate to reduce the possibility of moisture retention. Moisture encourages the growth of mold and may cause lids to rust. In addition, the lids often get stuck and may be difficult to unscrew.

To protect the jars from dust and insects, cover them with a cloth or paper. Keep them in a place where they will be safe from moisture and insects.

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