While navigating the death of a loved one, cremation can be an overwhelming and difficult process. For some of us, understanding how cremation works can help us grieve their loss and move towards a place where we can celebrate their lives.

Though cremation sounds straightforward, it’s actually a complex chemical process that varies depending on state laws and jurisdictions. Below, we’ve provided a basic overview of cremation to bring transparency into the process.

What Is Cremation?

Cremation is a funeral service that has been practiced for over 17,000 years. It involves returning human remains into their base elements: oxygen, carbon, hydrogen, and nitrogen. The result is white or light grey powdered ashes.

There are two common types of cremation used at a cremation facility: flame-based and alkaline hydrolysis. Flame-based cremation uses fire (fueled by propane), while alkaline hydrolysis uses a water-based process to encourage a quicker process. Flame-based cremation is the more common of the two, as alkaline hydrolysis is a newer form of cremation technology.

As we mentioned above, specific cremation guidelines vary from state to state. Don’t hesitate to ask questions when you talk to a funeral director, and be sure to choose a cremation service provider that is reputable, trustworthy, and has your loved one’s best interests in mind.

Fire-Based Cremation

Fire-based cremation is the oldest and most common form of cremation. Below, you’ll find a step-by-step explanation of the fire cremation process. 

Step One

The process begins when the cremation chamber, known as a retort, is preheated between 1400 and 1800 degrees Fahrenheit. Next, the body is placed in a heavy cardboard combustible container which is placed inside of the chamber. 

Step Two

Within the furnace-produced flames, the intense heat dries the body. As the remains burn, the bones calcify and crumble. During this process, the body emits natural gas that is released through an exhaust system.

Step Three

Some remains will need to enter the retort twice to be properly broken down, usually within a crematory’s afterburner. If a crematory doesn’t have a secondary burner, a professional will manually crush the skeletal remains into a powder.

Step Four

The remaining ashes may contain metal bits from the casket, pacemakers and other medical devices, the container, pins, implants, prosthesis, surgical screws, or dental work. After the ashes cool, the crematory retrieves these pieces with tools like magnets, then disposes of them. 

Step Five

Finally, a machine called a cremulator grinds the remaining bone fragments and ashes into a finer consistency. This process can take between one and three hours. After this process, the pounds of ash are given to an authorized family member or individual in a standard cremation urn or the desired urn of the family. 

Alkaline Hydrolysis

Alkaline hydrolysis is a newer form of cremation that uses water instead of fire. This involves more chemistry than fire-based cremation, and it’s a more environmentally friendly, gentler process. Alkaline hydrolysis has a smaller carbon footprint than fire cremation or burial in a cemetery, and it uses less fuel than fire cremation.

Below is the step-by-step process for alkaline hydrolysis cremation.

Step One

The body is placed in a single-chamber alkaline hydrolysis machine that is both watertight and airtight. This machine can hold about 100 gallons of liquid. Once the body is sealed into the machine, its chemical contents are balanced depending on the sex and weight of the deceased. 

These machines use alkaline chemicals like potassium hydroxide and sodium hydroxide to break chemical bonds down into their basic building blocks. Essentially, this mimics natural decomposition on an expedited scale. 

In contrast to the one to three-hour process of fire-based cremation, alkaline hydrolysis cremation takes anywhere from three to 16 hours. This time frame varies based on the body’s mass as well as the equipment used.

Step Two

Once the machine is finished, bone fragments are suspended in a sterile liquid. These white fragments are known as hydrolyzed remains. 

Similar to fire-based cremation, the remaining fat and tissues from the body are converted into basic elements and compounds. In fire-based cremation, these compounds are released into the air as vapor. In alkaline hydrolysis, these compounds are released through water in the cremation chamber. 

Step Three

Depending on state laws and federal laws, leftover water is transported to a wastewater treatment facility. In some instances, the water can be used as fertilizer thanks to its sodium and potassium contents.

Alkaline hydrolysis produces more cremated remains than fire-based cremation, so a larger urn may be required to transport remains to family members or authorized individuals.

The Process Outside the Process

The physical act of cremation is just one step within the burial process. In reality, cremation involves the transportation, storage, and return of our loved one’s remains in addition to the cremation itself. As mentioned before, processes will vary based on local and state laws.


After a loved one passes, their body can be transported to a funeral home or directly to a crematorium. Typically, the remains will initially be sent to a funeral home for the embalming process while friends and family consider their next steps. 

Sometimes, a loved one will leave end-of-life instructions to aid in funeral planning and burial preparation. If not, you may need time to discuss how to best honor your loved one’s wishes. 


In addition to cremation and burial decisions, the next of kin need to complete paperwork (like a death certificate) and begin planning memorial services. Making these choices can feel stressful, and you should take all the time you need. 

In order to give loved ones the time and space to process, the body is placed in cold storage. The typical time period between death and cremation is 48 hours, but the body can be preserved for as long as necessary.


If you choose to cremate your loved one, their body will be sent to a crematorium. Depending on the cremation method, this step can take between three and 16 hours. During this time, you can choose an urn for your loved one’s ashes.


Once the cremation process has finished, your loved one’s ashes will be returned to you in the urn of your choosing. If you have yet to choose an urn, the crematorium will typically place the ashes in a plastic bag. The ashes will then be returned to the authorized individual. 

These steps comprise a simple outline of the cremation process. However, it also involves paperwork, analysis, planning, transportation, preservation, and time to grieve.

Next Steps

It can be difficult to move on after a loved one’s cremation. The options for your next steps may seem endless. While some choose to scatter their loved one’s ashes in a meaningful location or display them in a place of honor in the home, you may want a more concrete piece of your loved one to keep with you wherever you go. 

Eterneva allows you to transform your loved one’s ashes into a radiant and beautiful piece of diamond jewelry that you can personalize to capture their essence for eternity. A wearable diamond is a priceless opportunity to celebrate this unforgettable connection and honor the bright light they created in your life. 

Because ashes contain carbon, they can be used to grow a diamond using a combination of pressure, heat, and time. The diamond creation process is an opportunity to share cherished memories of your loved ones with Eterneva’s team to make a unique diamond memorial that reflects their singular impact on your life. 

Similar to a tombstone, a diamond is a concrete memory of your loved one, except you can wear their memory around your neck,on your finger, and more. You can carry this portable memorial through all of life’s milestones, creating a physical connection to this remarkable person even after they’ve passed on. 

Moving Forward

Learning about the different types of cremation can help make these difficult decisions a little bit easier. As with any important decision, you should take the time you need to make the best choices for yourself, your family, and your loved one. 

This step-by-step outline of the cremation process puts a complicated process into simpler terms so that you have all of the information you need to make the best decision. Once these logistical choices have been made, you can begin the complex process of grieving your loved one, celebrating the positive impact they had on your life, and finding special ways to keep their story alive


Cremation Process | Cremation Association

What Is Alkaline Hydrolysis? | VeryWell Health

How Is A Body Cremated? | Cremation Resource