material knowledge

[Meredin]

Hello dear forum members. This is my first post in english so barre with me on the spelling. Thanks for all the great info on the forum. Im not sure this quistion is in the right place -sorry in advance!
I have acces to old moler stones (fairly cheap) I know its a building brick that insulates and does not contain heat. Its very airy brick - actually it floats on water. On Wikipedia its only descriped in danish and info is only about the new very expensive modded bricks but Mass is 450^[2]-960^[1] kg/m³. Its a mineral diatoméer (kiselgur) its also found in ireland i cant remember the exact place..
its the main part in catlitter- it sucks water lige sponge and is not weatherproof ( inside brick use for masonary)

Does anyone know this kind of brick? Im planning to build a pizzadome next year. Yes i know its not the regular firebrick but maybe i can incorporate it in my build.
Very expensive Modified bricks with moler is used in furnaces with very high temperatures, some mixed with ex vermiculite from a danish company https://www.skamol.com/

i know its a bit special request and Hope to hear your replays. Cheers
/Meredin

[MarkJerling]

If it floats, it's obviously not going to hold heat, so while it can handle heat, it will not be a good brick for an oven.

[Gulf]

Depending on the crush strength you may be able to us them as under floor insulation and/or buttressing.

[Meredin]

Thanks for the very quick reply Mark. We'll I guess it's the same principle for a perlite or vercumilite dome then?

Is it posible to combine chamotte bricks and molerstones? I know there is a huge weight difference between the 2 brick types but also in prices. The oven i have plans on building is a one night stand oven and is not surposed to be hot the next day or morning. I know that came out wrong.
If its possible to retain the heat inside an oven with, maybe only the floor and a couple or more circles in the dome beeing chamotte bricks. Or maybe as an insulated layer on the bottom concrete.

Anyway im more interested in the durability of molerstones in the first place.

[fox]

Insulating bricks have many uses but they will repel heat and not store it, great for building the gallery but not the dome.
They may not survive any direct flame or anywhere in the direct flame path but should survive the gallery and possibly the chimney.
What you really need is a dater sheet.

[Meredin]

Thanks for your replys. Molerstones is out. Guys I have a quistion regarding fibres,- if I'm going to cast some of the flue connection. I read on the forum that David S mentioned polypropylene as additive is used in the cement, clay and limestone mix. It will burnout at 160. Im not fond of using plastic. Can rope from organic materials be used instead? Hamp or other types?

I have now cement, lime, and the clay type that have low shrinkage at 3-400 celcius is at request at the local caramic. Maybe ballclay.
In spring I will look at my budget and wife (build time) and decide if all brick/semicast or perlite is the way to go. I will be prepared.
cheers.

[david s]

Thanks for your replys. Molerstones is out. Guys I have a quistion regarding fibres,- if I'm going to cast some of the flue connection. I read on the forum that David S mentioned polypropylene as additive is used in the cement, clay and limestone mix. It will burnout at 160. Im not fond of using plastic. Can rope from organic materials be used instead? Hamp or other types?

I have now cement, lime, and the clay type that have low shrinkage at 3-400 celcius is at request at the local caramic. Maybe ballclay.
In spring I will look at my budget and wife (build time) and decide if all brick/semicast or perlite is the way to go. I will be prepared.
cheers.

Hi Meredin,

You could try human hair. Not sure at what temperature it will burn away. It needs to be very low (under 200C) or it will not work to protect from the steam spalling issue. Take a very small sample and place it in your kitchen oven at 200C to see what happens. Although burning hair stinks.