Paperclay: Insulating with paper pulp

[Deleted]

Paperclay's or papercrete's R-value is reported to be within 2.0 and 3.0 per inch,
which is in the range of perlite and vermiculite or higher.
After the fibers are burned out the R-value will be even higher.
en.wikipedia.org/wiki/Paper_clay
en.wikipedia.org/wiki/Papercrete
en.wikipedia.org/wiki/R-value_%28insulation%29

According to the following article it can withstand even higher temperatures than
the used clay without any refractory.
www.grahamhay.com.au/gault2004cap.html

See also:
www.tinaneale.co.uk/paperclay/4543949041
www.livinginpaper.com/index.htm
www.mortarsprayer.com/papercrete/mix-papercrete/

[countryatheart]

Thanks for the info. I can't wait to discuss this with my Papercrete group!

[Deleted]

Papercrete reminds me of something.

Adding about 10% of cement will increase insulation to.
Fire clay shrinks about 10 to 15% after water dries out.
Paperclay schrinks even more as paper mache shrinks up to 25%
The cement will harden the mix long before all the water is out
and thus gives 10% to 15% more voids per volume.

Instead of paper one could use cellulose insulation,
which is not expensive and ready to use.
Cellulose insulation is manufactured with boron and borax
to prevent spoilage and to make it more fire resistant.
Ash from the paper, and borax in the cellulose will act as a slight flux in the clay body.
According to the following site a cone 10 (1285°C to 1305°C) porcelain body can still be fired at cone 6 (1222°C to 1243°C), lowered only by about 60°C.
www.jerrybennett.net/paperclay.html

I'm very happy with my Paperclaycrete experiment,
which I have fired while it still was quite wett.
No cracks or other issues.

[leewaytoo]

"The cement will harden the mix long before all the water is out".

traps the water?

[Deleted]

Posted by leewaytoo on Yesterday at 2:09pm

traps the water?

No, it will dry even faster because of the altered properties.

[satamax]

Karl, something comming to mind reading this. In Ianto Evans book, he talks about using ashes iirc, as an insulation for the heat riser of rocket stoves.

Mixing ashes with castable refractory, could may be give good results no?

I have six or seven bags of ash shavings from the last stairs i made, and i thought this could have been an option too.

[Deleted]

Posted by satamax on Today at 12:11pm

Mixing ashes with castable refractory, could may be give good results no?

Of course one can use ashes, but the resulting Insulation will not be as good as using something that can burn out.
The ashes will not be reduced by the heat, thus there will be only the voids that have been in the ashes before, aside the holes at the surface of the ashes which will be filled eventually.

Aside of insulation wood ash is used as a binder and stabiliser as it contains a significant
amount of CaO (burnt lime ). Depending on the mixture it may even start a pozzolanic reaction e.g. with crushed burnt clay ( grog ).
However this aspect is senseless with castable refractory that does not bind solely by heat.

Oh, I've almost forgot:
Any kind of hydraulic reaction started by the wood ash will raise the heat conduction of clay/cob, especialy if a pozzolanic reaction creates some kind of roman cement.