Go back to previous page
Forum URL: http://www.truefresco.com/cgidir/dcforum/dcboard.cgi
Forum Name: Plaster Arts & Modern Plasters and Classic Finishes with Joe Greco
Topic ID: 33
#0, Magnesite Marble & Terracotta
Posted by Gary sculptari on 13-Jun-04 at 07:32 PM
I thought it would be interesting to pass on some of why findings regarding magnesium oxychloride cement, patented in 1800's as Sorel's cement. It is important because it may easily be mistaken as scagliola or stucco - but is an entirely different material chemically. It is interesting that it is a totally natural cement, based on dried up ancient oceans for its two components

The modern variation is 10,000 to 12,000 psi compressive strength - thats up around Moh 2 on another scale - like grantite - no gypsums or cements can approach that level without a lot of special modifications. Plain portland cement is about 2,000 psi.

It is completely fireproof - up to 2300 degrees fahrenheit and can withstand a tensile shock. It is simply the very best flooring and wall material available. It resists both acids and solvents.

Here is a link explaining some of its historic use in the los angeles area:
http://homeandhearth.keenesentinel.com/design.htm#2

Restorers should also be aware that early practitioners added cheap, asbestos fiber as a bulking filler. Another filler is wood flour, because unlike lime or cement, this material is not alkaline and can use organic fillers - like wood, straw or hemp. It shrinks very slightly, so a lot of hard sand filler is not needed. It cures in four hours and does not require continuous wet.

It has fallen out of favour because it is expensive compared to standard concrete and gypsum. But there is simply no substitute for scultped and or highly polished finishes.


#1, RE: Magnesite Marble & Terracotta
Posted by Yin on 17-Aug-04 at 01:05 AM
In response to message #0
We are glad to learn you are familiar with magnesium oxychloride cement (MOC). In China, these material are pretty cheap since the best and most abundant MgO mine is located in Haicheng, China. Now Chinese use MOC to product fire board, the price is a little higher than gypsum board.

We would like to know what is evaluation about quality for Magnesite Floor after so many years of use and is there any company still interesting in promoting Magnesite Floors and has the relative technology.



#2, RE: Magnesite Marble & Terracotta
Posted by maria holden on 23-May-05 at 08:16 PM
In response to message #0
Hi Gary,
Please see my post of 23 May. I'm hoping you might have some very needed input!
Thanks!

#3, RE: Magnesite Marble & Terracotta
Posted by Mirek Koalicki on 05-Dec-05 at 11:54 AM
In response to message #0
How this cement stends to elements,what do people
mix with it to make water resistant?

#4, RE: Magnesite Marble & Terracotta
Posted by bobby tucker on 25-Apr-06 at 07:00 PM
In response to message #0
>I thought it would be interesting to pass on
>some of why findings regarding magnesium
>oxychloride cement, patented in 1800's as
>Sorel's cement. It is important because it may
>easily be mistaken as scagliola or stucco - but
>is an entirely different material chemically. It
>is interesting that it is a totally natural
>cement, based on dried up ancient oceans for its
>two components
>
>The modern variation is 10,000 to 12,000 psi
>compressive strength - thats up around Moh 2 on
>another scale - like grantite - no gypsums or
>cements can approach that level without a lot of
>special modifications. Plain portland cement is
>about 2,000 psi.
>
>It is completely fireproof - up to 2300 degrees
>fahrenheit and can withstand a tensile shock. It
>is simply the very best flooring and wall
>material available. It resists both acids and
>solvents.
>
>Here is a link explaining some of its historic
>use in the los angeles area:
>http://homeandhearth.keenesentinel.com/design.htm#2
>
>Restorers should also be aware that early
>practitioners added cheap, asbestos fiber as a
>bulking filler. Another filler is wood flour,
>because unlike lime or cement, this material is
>not alkaline and can use organic fillers - like
>wood, straw or hemp. It shrinks very slightly,
>so a lot of hard sand filler is not needed. It
>cures in four hours and does not require
>continuous wet.
>
>It has fallen out of favour because it is
>expensive compared to standard concrete and
>gypsum. But there is simply no substitute for
>scultped and or highly polished finishes.

#5, RE: Magnesite Marble & Terracotta
Posted by Tracy on 01-Sep-06 at 07:49 AM
In response to message #0
Gary,

I am new to the truefrescoe website, and just read this old postingof yours. I wonder if you are familiar with suppliers of this product. I am looking for a good substitute for gypsum plaster for my artwork, and this sounds like it might be worth investigating.

Thanks for any help you cna give. I am in California, USA, btw.


#6, RE: Magnesite Marble & Terracotta
Posted by Gary on 02-Sep-06 at 06:29 PM
In response to message #5
A supplier of small quantities in CA is Hill Brothers. This company should be huge, but unfortunately, in the early days, one of the favoured ways of strengthening and lowering the cost of magnesite was to add asbestos. The law suits have palgued the company IMHO.

It is beautiful to cast with - I have made very convincing black onyx and lapis lazuli that would fool jewellers - because it is as hard as natural stone and does not burn under the torch.

IT is really hard, completely fireproof, and more expensive than gypsum plaster. What i do is "dilute" the cement with extremely fine bubbles generated by CO2 gas, to form a very stable and weatherproof carving stone. Weights can vary to harder than granite, to soft as styrofoam.


#7, RE: Magnesite Marble & Terracotta
Posted by Jeneroo on 08-Jul-07 at 07:22 AM
In response to message #6
Hi, I have just started experimenting with magnesite as a casting material, right now with a product from a floor company, but I am not yet convinced... would be ever so thankful for more information of how you have made such strong materials, and particularly how you do this "dilution" process with CO2... Thank you so much for information!!!!

#8, RE: Magnesite Marble & Terracotta
Posted by Gary sculptari on 17-Jul-07 at 04:55 PM
In response to message #7
Here is a more up to date link:

http://www.geoswan.com/html/mgo2424.html


#9, RE: Magnesite Marble & Terracotta
Posted by Jeneroo on 20-Jul-07 at 11:10 AM
In response to message #8
Dear Gary,

Thanks so much for the very helpful link. Unfortunately, though, I was not able to find much practical information for the artistic use of magnesite cement... The one link which is labeled artistic uses didn't bring me to anything of the kind...

How did you develop the experience and know how to be able to create the materials you describe (from soft to hard, imitation stone, etc...)

Most of all, I am especially curious:
What was that about diluting with air bubbles????

Would be very extremely thankful for more information!!

Jennifer, jen@worldlinked.net