What are ashes? | Cremation ashes explained | Eirene Urn Store

In a funeral setting, the term “ashes” is used to describe the leftover remains after the cremation process, sometimes referred to as cremated remains or cremains. But what exactly are “ashes”? This article will explain what ashes are made of and how they are produced. 

What are cremation ashes? 

In a general sense, ashes are what is left over after something has been burned. It is a powdery substance or residue made of unburned particles remaining after something has been burned or oxidized by chemical means. 

Cremation ashes are what is left over of a body after cremation. In flame cremation, a body is exposed to extreme heat or in liquid cremation (also called aquamation) it is exposed to heat, water and pressure. These processes reduce organic matter into bone fragments. These fragments are then reduced further into a fine, coarse grey powder, similar to coarse sand; these are the ashes. 

What do cremated ashes consist of? 

Cremation ashes mainly consist of bone fragments. However, there are also remnants of chemicals and compounds found in the body before the cremation process. 

One of the main components of the human body is water; however, there are also large amounts of other compounds (e.g., oxygen, hydrogren and carbon) and minerals found within our bodies. Chemical composition varies from person to person, but we also have these general components in our bodies. 

When bodies go through cremation, much of these compounds are consumed by extreme heat or are oxidized. However, not all is destroyed in the process, primarily the constituent materials in bone. 

Human bones are made mostly of collagen, but this is a soft tissue that would not withstand the extreme conditions of cremation. However, bones also contain calcium phosphate to strengthen and harden them; this compound often remains in bone fragments. Therefore, ashes consist mainly of calcium phosphates and small amounts of minerals like potassium and sodium. Most sulphur and carbon are oxidized, but approximately 1 to 4 per cent of the carbon in the body remains as carbonate.  

Since much of the ashes consists of bone fragments, the quantity of ashes will vary more on height than weight. Nonetheless, the remains from the average adult will weigh around 4 to 8 pounds. 

You can follow the general guideline below to determine how much ashes will remain after cremation.   

Before cremation, each pound (or half a kilogram) of body weight equals approximately one cubic inch (16.3 cubic cm) of ashes. If someone were 175 lbs (79.4 kg) before cremation, they would need an urn with a capacity of at least 175 cubic inches (2868 cubic cm). However, this can vary depending on the type of cremation chosen. 

How are cremation ashes produced? 

As mentioned above, ashes are produced through the process of cremation. Cremation can occur in two ways – flame cremation or aquamation. Flame cremation creates ashes by exposing the body to extreme heat, and aquamation does so through the chemical process of alkaline hydrolysis. 

Flame cremation consists of several stages that can take up to three hours. First, the casket or container is placed in the cremation chamber, where it is subjected to temperatures ranging from 760 to 980 Celsius. 

The body is consumed by the extreme heat in the chamber, except for bone and any non-combustible materials. The cremated remains are removed from the chamber. After a cooling period, any remaining metal or orthopaedic implants are separated from the remains, and then they are recycled. Any remaining bone fragments are mechanically processed into fine particles and placed in a container or urn. 

Alkaline hydrolysis produces a similar end-product, but the body is treated with a combination of water, alkali (potassium hydroxide), heat, and pressure instead. 

The treatment produces a reaction that speeds up the decomposition of the body. The entire process typically takes between three and 16 hours to complete. When finished, it leaves behind bone fragments, which are mechanically processed into a powder; and a sterile liquid; that can be disposed of through the sewer or wastewater system. 

Ashes produced have a slightly different appearance than those made with flame cremation. Ashes from flame cremation are often grey, with a more coarse consistency. In contrast, ashes from aquamation are often a white or tan colour, with a more consistent, smooth, powder consistency. Aquamation also produces 20-30 per cent more ash than flame cremation. 

After cremation, ashes are scattered, buried or kept in a cremation urn by the family.

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