Memory Glass is a little different than normal glass because it contains a very special foreign substance: cremated human remains.
Memory Glass is a type of Funerary Glass
The term 'Memory Glass' refers to solid glass sculptures and keepsake jewelry that contains the cremated remains of friends, family and beloved pets. In these unique art pieces, bone ash is incorporated right into the glass mixture and appears as puffy white clouds under a transparent surface. Sometimes called Funerary Glass this art form is as old as the Romans and has come in and out of style for twenty centuries. Today in 2015, due to shrinking cremation service costs at Basic Funerals and other online undertakers, Memory Glass is coming back into mainstream funeral fashion.
Today beautiful memory glass centers on striking the perfect balance between art glass and the aggregate cremated material which does NOT bond with the glass itself but makes bubbles of white creamy clouds inside the piece. The article on how Cheaper Cremations Increases Funeray Glass on Digital Journal shows Angelo Rossi at Skylon Tower Niagara Falls at work making memory glass and also shows his various shapes, styles and stockpiles of the stuff.
The sifted ashes are delivered from the funeral home in a small glass jar, usually by the funeral director, complete with the paper tags bearing the name and number of the deceased.
Are there glass making chemical components inside human remains?
The Cremation Process is Very Efficient
Commercial crematoriums are designed to produce temperatures between 870–980 °C, though in some situations much higher temperatures are possible, depending on the configuration and off gassing designs. Larger bodies take longer, especially where there's excessive body fat. The time it takes to cremate a body depends primarily on the size of the body..
So what is left at the end? Bone ashes. We call them 'cremated remains' but its a fact that they are the non-burnable elements of the body. For the most part, this is just bones and teeth of the human skeleton.
Cremation temps of approx 800°C vaporizes almost all the tissue in the body, and what remains is the hardest most dense material.
Other things like dental and surgical prostheses may also remain in the ashes, and are usually sifted out of the powder along with larger bone fragments before the dust is delivered to the families of the deceased in a clear plastic bag.
The mineral in bone is hydroxylapatite, a type of calcium phosphate with the formula, Ca5(PO4)3(OH). But in the heat of cremation, it’s at least partly transformed into tricalcium phosphate, or Ca3(PO4)2.
The bone dust is delivered to the glassblower in a small glass jar with the official name and death certificate number of the deceased.
Technical difficulties of making memory glass with cremated remains
The technical difficulties of making memory glass with cremated human remains has a lot to due with expansion co efficiencies of ashes which are three times more expansive than soda lime material. If this foreign material had any density it would certainly crack the glass either while cooling or in future heating and cooling of the glass vessel.
When an object is heated or cooled, its length changes by an amount proportional to the original length and the change in temperature. Linear thermal expansion of an object can be expressed as
dl = L0 α (t1 - t0) (1)
dl = change in length (m, inches)
L0 = initial length (m, inches)
α = linear expansion coefficient (m/moC, in/inoF)
t0 = initial temperature (oC, oF)
t1 = final temperature (oC, oF)
Eric Davy, funerary glassblower in Toronto and principal at Davy Glass specializes in making Memory Glass paperweights. When creating these art glass items he adds the cremated remains into the mix before the first gather, and as the powder expands in the glass it makes wonderful puffy white clouds.
But of course they weaken the glass - not that a paperweight has to be very strong. According to physics its important to note that if the paperweight were to be heated and then rapidly cooled it would break along lines made by the ashes inside.
Linear Temperature Expansion Co efficiency of Calcium Compared to Glass
- α -
(10-6 m/(m K))*) , (10-6 in/(in R))*)
Modern glass composition is 65% silica, 25% soda, 10% lime. Silica is the most common element on planet Earth. The oxide is SiO2 and is added to soda, Na2CO3 and lime.
Lime is a calcium-containing inorganic material in which carbonates, oxides and hydroxides predominate. Strictly speaking, lime is calcium oxide and or calcium hydroxide. It is also the name of the natural mineral (native lime) CaO.
Like most 'Hot Glass Artists' today, Eric Davy and his assistant Alex Wilson use Studio Nuggets delivered direct to the shop in the 50lb bags seen below.
Soda lime glass is the most common type of glass today, representing 80% of all commercial glass. This substance is extremely important in our day to day lives because it’s used everywhere, in windows, jars, jugs, bottles and drinking glasses. Art glass blowers who make Memory Glass generally buy and use Studio Nuggets soda lime glass pellets which promise the following composition of 60-75% silica , 12-18% soda, 5-12% lime and nothing else.
Making a paperweight with cremated remains inside.
The finished glass paperweight is beautiful to behold!
You can see some insightful pictures and read the story about Eric Davy making funerary glass on Dumpiggers, and also I put some other shots of glassblowing a funeral urn on Antique Bottles discussion forum.