documented research on fibrous plasters

[patamos]

Hi Folks,

I'm in a process of nutting out some parameters for construction of double skin heaters with a 4" thick clay brick core and 1" fibrous brown-coat as the outer skin.  I know this is done often in Europe, but North American regulatory authorities are unfamiliar with the approach.  Can anyone point me towards published research on this topic?  Or suggest names of stove builders who follow this practice?



many thanks  



pat 

[Deleted]

Someone has filed a patent for clay plaster.
www.google.com/patents/US8007586

Search at Google Scholar:

fibrous clay plaster
scholar.google.com/scholar?hl=de&as_sdt=0%2C5&q=fibrous+clay+plaster&btnG=

refractory fibrous clay plaster
scholar.google.com/scholar?hl=de&as_sdt=0%2C5&q=refractory+fibrous+clay+plaster&btnG=

[patamos]

Thanks Karl,

I'm very grateful that you have returned to this forum...

I did a fair bit of surfing from those leads but didn't find the emphasis i was looking for. Lots of good info about expanding clays relative to humidity though.

What i am seeking is information on elasticity/resiliency under repeated thermal cycling. I have been building my bell chambers with red clay brick pavers and then covering the walls with 2 layers of browncoat plaster (clay sand and finely chopped straw fibre), and i appear to be spearheading some research on which types of clay will be best suited to creating a cob skin that can expand and contract slightly with the clay brick (and clay-sand mortar) sub structure.

I'll keep browsing…

Your suggestions are always appreciated

[fzurzolo]

Hi Patamos,

You are directly plastering onto the brick heater body?  And this is not resulting in significant cracking of the plaster skin? How long have these directly adhered plasters been "in use" for without cracking?

In my experience with using cob for ovens, the expansion and contraction is significant and causes cracking in materials that expand at different rates (I,e, lime plaster over cob, or even rich clay plaster over lean clay plaster). Could it be that your plaster and the underlying brick structure are similar enough in their thermal expansion rates that they move "in unison"?

I am very interested in this because until now I have been trying to figure out how to make a plaster skin on a heater without significant framing effort around the core.