The Composition of Human Cremated Remains

Jul 10, 2015 | 6 comments

If you’ve ever wondered why cremated remains can look so different, this guest article by Nick Savage, President of Memory Glass, has all the answers, down to the chemical composition of human cremated remains.

What Exactly are Cremated Remains?

As funeral directors, crematory operators, and even as a glass keepsake manufacturer, we deal with cremated remains every day, it’s our business. The cremation rate in the United States has risen so dramatically and so quickly that even in the most remote and traditional areas of the country, it’s basically impossible to ignore cremation any longer. So, what exactly are these “cremated remains” that we are subjected to regularly?

As a manufacturer of glass keepsakes that incorporate cremated remains directly into the pieces, we see cremated remains from over 1600 funeral homes, and an uncommon amount originating from different retorts from around the world.

The color of these cremated remains range from almost completely black to stark white, with all shades of gray in between as well as oddities such as green, red, yellow, brown and slightly bluish. Seeing these variations, coupled with my background in anthropology, sparked my investigation into exactly what we are all looking at after a cremation.

I set out to research and evaluate the chemical breakdown of the human body prior to cremation and post cremation, and compare the results.

I immediately thought of Walter White, from AMC’s TV series “Breaking Bad,” as he explains this early on in the show. The data he presents on his chalkboard is, for the most part, accurate.

They show the elements in the human body represented in percentages. Below is an info-graphic from that is quite similar to Walter’s data (the percentages aren’t perfect though, specifically Ca & P are low). Note one important fact: 96% of the body mass consists of four elements: Oxygen, Nitrogen, Hydrogen and Carbon.

Elements in the Body from chemistry.about.comUsing the numbers from the info-graphic above, we should be able to calculate an approximate (extreme body to bone ratios will change things dramatically) amount of expected cremated remains from an average body, simply based on its weight. All we would need to know is the boiling points of each element within the body prior to cremation.

My first instinct (which was wrong) told me that any element that boils at a lower temperature than experienced in a retort should evaporate, and no longer be present in the cremated remains; and anything with a boiling point greater than retort temps will survive. After speaking with a colleague in the chemistry world other than Walter White, I learned this was generally true, but there were exceptions, which REALLY matter in this case.

Boiling Point of Human ElementsRemember that 96% of the body is composed of four elements. Those four elements leave the body and retort as gasses, mainly CO2, CO and H2O, (carbon dioxide, carbon monoxide, and water/steam). Here, my “first instinct” wasn’t exactly correct.

It turns out phosphorus, with a boiling point below 1400°F, doesn’t exit the retort during the cremation process that typically goes well above that temperature. Being stored in bones as calcium phosphate (a highly stable inorganic compound) allows it to survive the cremation temperatures and merely dehydrate and decompose until forming tri-calcium phosphate, or what we commonly know as cremated remains.

There are numerous trace elements found in the body that have much higher boiling temperatures than what are achieved in a retort, such as Manganese, Copper, Chromium, Iron, Molybdenum, etc. These elements collectively account for less than 0.1% of the human body’s composition, and don’t affect the quantity of cremated remains very much, but may affect the appearance of the cremation itself as some of these elements will form carbonates in combustion environments.

I have a theory that Gadolinium (introduced to the body as a contrast medium for CT and MRI scans) sticks around in the cremated remains and can create strange, unique bubbles when encased in molten glass keepsakes. The bubble blowing cremated remains are usually darker in coloration, so it seems that something other than tri-calcium phosphate is surviving the cremation process.

Now, going back to the info-graphic, we can use this knowledge to determine an approximate weight of cremated remains expected from an average cremation.

  • Calcium + Phosphate = tri-calcium phosphate
  • Tri-calcium phosphate = 3.5% of the human body
  • 5% of 175 lb (average male) = 6.2 lbs of cremated remains = average cremation weight

What this means is that for the most part, when you are holding a filled urn, you are holding tri-calcium phosphate with a pinch of carbonates. Does this explain why cremated remains look different from one retort to the next? Or even from one cremation to the next? Sort of.

Every cremation has numerous variables that determine the color and physical makeup of the cremated remains. Seemingly, the variables are infinite, and in a way they are. But the four most important ones are:

  1. Time in the retort
  2. Temperature in the retort
  3. Ratio of body to bone (this requires changes in time and temperature)
  4. Levels of trace elements in body

During the cremation process, there are three visually noticeable stages that occur as the temperature is increased. As temps reach 572°F, bones begin to brown or blacken as organic components carbonize. As we approach 1400°F, bones become black or dark gray depending on duration. Once 1472°F+ is achieved, bone becomes calcined and color changes to light gray or white depending on duration.

Here, carbon bonds with oxygen and escapes as CO2. Technically, at this temperature, the cremated remains are created when the calcium and phosphate stored in the bones as hydroxyapatite converts to tri-calcium phosphate with a boiling point of 2535°F. However, if you get your retort that hot, it will begin to melt down.

So, what this tells us is that when we see cremated remains that are dark gray or black, there is really only ONE controllable problem, with TWO correctable causes:

  1. Not in the retort long enough at proper temperature
    • Cause: Proper temperature not achieved.
      • Solution: Temperature Controller Errors
      • Solution: Bad Thermocouple
      • Solution: Programming Error
    • Cause: Proper temperature achieved, but not maintained for proper duration
      • Solution: Temperature Controller Errors
      • Solution: Programming Error
      • Solution: Body to bone ratio issues

If you are experiencing any of these problematic results, I would recommend contacting your retort manufacturer to discuss these issues, as only they will have the proper information for diagnosing your specific system.

The uncontrollable “problem” is theoretical. Every cremation is going to have its own set of variables. Each body will have its own levels of trace elements. The ratio of bone to body is different EVERY time. The composition of the casket or container being burned will change regularly.

All of these add up to a basically infinite number of variables that cannot be controlled completely, and theoretically have the capacity to affect the actual process of the cremation, and in turn, the color of the cremated remains.

In the end, cremated remains are going to look slightly different each time, but getting them more consistent in order to meet client expectations is the goal. No one wants to have to explain to a family why their loved one’s cremated remains look so different (in color or texture) from the ones they may have at home of previously cremated family members.

However, each individual is unique while living, and it turns out that they do indeed retain a bit of their individuality after cremation.

Nick Savage Memory Glass

Nick Savage, President, Memory Glass

Nick Savage is the President at Memory Glass, a glass memorial company specializing in the memorialization of cremated remains. He founded the company in 2001, growing it to become a well-established industry leader in cremation memorialization. His expertise includes business management, working with hot glass, building equipment, woodworking, metalworking web design, computer programming, and housing construction. Contact Nick at, or visit Memory Glass at

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