• Post Reply Bookmark Topic Watch Topic
  • New Topic
permaculture forums growies critters building homesteading energy monies kitchen purity ungarbage community wilderness fiber arts art permaculture artisans regional education skip experiences global resources cider press projects digital market permies.com pie forums private forums all forums
this forum made possible by our volunteer staff, including ...
master stewards:
  • Carla Burke
  • John F Dean
  • Nancy Reading
  • r ranson
  • Jay Angler
  • Pearl Sutton
  • paul wheaton
  • Leigh Tate
  • Burra Maluca
master gardeners:
  • Christopher Weeks
  • Timothy Norton
  • Jeremy VanGelder
  • Paul Fookes
  • Tina Wolf
  • Likes 4
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator

Listen Online

Get all of the Podcasts in convenient, giant zip files
Subscribe on iTunes


Paul sits back down and gets last remaining instructor, Lisa Orr, along with Chris McClellan, aka Uncle Mud, to go more into their Rocket Kiln stuff.

The latest rocket kiln is the fifth prototype in the series, with the first being built by Ernie Wisner and was somewhat dear to Paul as a sort of “not so great” version to try and keep people from re-inventing the Mk.1 mistakes (although it’s removal didn’t seem to invite much failure in the latest version).  While Lisa and Rodney Morgan were making stoves for the Free Heat Movie, Rodney was fiddling with the chimney (technically called tuning the riser), Lisa used a pyrometer to measure the effects of his tuning on the kiln’s temperature.  She also used little glazed “cones” to measure both the overall temperature and the distribution of any hot or cold spots in the kiln by checking to see which glazes had melted after firing them.  

The kiln built during the Rocket Mass Heater Jamboree got to a gas temperature of about 2200 degrees according to the pyrometer, whereas the cones (which measure the temperature that pottery will get to) recorded closer to 2000 degrees.  The delicate blue glaze they put in as a test even got fired properly with no reduction or discolouration, outside of the one they put at the bottom of the J-tube.  

The PTJ rocket kiln has been built around a full-size 8-inch J-tube rather than the smaller tubes used by prior prototypes to try and make it less of an iterative prototype and maybe stick around longer.  Yes, this will increase wood consumption, but it’s still an order of magnitude or two less than the amount used by Lisa’s old job that took several trailers full per firing, to say nothing about how much less hassle it is to not have to notify the fire department and rest of the postcode every time it’s lit.

Relevant Threads

2023 Permaculture Technology Jamboree website

8-Inch Portable Modular Rocket Engine with Forge, Crucible, and Kiln Attachments
Podcast 587 - 2021 RMH Jamboree So Far - Part 1 (Part 2)
Free Heat Movie
Rocket Stoves forum

Support the Empire

Help support the empire and get all of the podcasts in a bundle here in the digital market at permies.

To support production of these podcasts, make a donation here at Paul's Patreon page.

This podcast was made possible thanks to:

Dr. Hugh Gill Kultur
Kyle Neath
Bill Crim
Chris Sugg
Kerry JustTooLazy
Jocelyn Campbell
Bill Erickson
G Cooper
Dominic Crolius
Penny McLoughlin
Mehron Kugler
Pasquale DeAngelis
Julia Winter, world's slowest mosaic artist
Greg Martin
Sean Benedict
Rita Bliden
Dana Martin
Candace Dahlk
Keith Kuhnsman
Eric Tolbert
Nick DePuy
Nathan Hale
Opalyn Rose
Polly Jayne Smyth
Todd Gerardot
Katie Young
Ivar Vasara
Brent Lawson
Weston prestage
Candice Crawford
Chris Holtslag
Song Zheng
I'm not dead! I feel happy! I'd like to go for a walk! I'll even read a tiny ad:
Native Bee Guide - now FREE for a while
    Bookmark Topic Watch Topic
  • New Topic