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Post by PNW Dave on Sept 2, 2014 16:33:25 GMT -8
I forgot to mention the sonotube section I placed on top during the burn. It's yet another test mix, this one is with the black furnace cement from my first post, with perlite and fire clay. Packed between 8" and 12" sonotube forms.
It is garbage. Fragile, cracking and would not stay together if I removed the outer form. It does fit nicely over the stove allowing the flames to spread out a bit instead of being focused right in the center of the pan.
I'm guessing it is so weak because I thinned the furnace cement with too much water before mixing with the perlite/fireclay.
From my little stove build I've come to appreciate how dry a mix can actually be and how beneficial it is.
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Post by PNW Dave on Oct 5, 2014 13:21:59 GMT -8
First, my question. Does anyone have any recommendations on how hot and for how long I should fire these? (In a real kiln, and I have a sample brick to test fire first) I've made a couple heat riser sections for my upcoming 8" system. The riser sections are 10" tall each and will be stacked on the core, once it is built. I used a similar mix as the 5 gallon test stove in the video I posted earlier. Heat riser mix: - 15 parts perlite - 2 parts fire clay (Repeatedly misted perlite with water, dusted with fire clay, and mixed to coat) - 1.25 parts furnace cement - 1.25 parts water glass - maybe 1/3 cup of thin clay slip (Mixed furnace cement and water glass and added slip to get a consistency that will pour in a thin stream, to drizzle onto coated perlite while mixing) A couple pics- The first riser section I made (bottom one) was mixed a little too wet, stuck to the form and lost some material. The second one I wrapped the form in wax paper and removed it from the form just minutes after ramming, it came out easily and looks much nicer.     |
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Post by PNW Dave on Oct 6, 2014 20:50:07 GMT -8
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Post by ericvw on Oct 7, 2014 2:04:40 GMT -8
Hey DavidEaks,
Those riser sleeves look great, man! A lot better than my cast ones which cracked up from overheating... Don't know about kiln times if that's what u were saying a couple of posts ago- was there anything about the similar mix in that old patent post Donkey put up? I've only read part of it.
Can't wait to see it spitting Fire man!
Eric VW
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Post by PNW Dave on Oct 7, 2014 3:58:03 GMT -8
Thanks Eric! Yes, I was wondering about kiln time/temp. With this crazy mix I've come up with I don't know if all the materials will withstand the temperature needed for the fire clay to fully mature. Although, it probably won't even be necessary.
I guess Karl already answered part of the equation in his earlier post, stating that sintering begins between 1472-1652 Fahrenheit (800-900 Celsius), I'm thinking around 1500-1700F... I just looked through that insulating perlite link and they were firing between 1400-1750F for 1-2 hours. The furnace cement is rated at 2000F and wiki says sodium silicate melts at 1990F. So it seems things are in good order.
The first riser sleeve I made (the one that stuck to the form) has 2-3 significant cracks on the outside face but the inside face doesn't really show the cracks and it still feels nice and solid. I suspect I burned too hot for too long too soon after removing it from the form. Once dry, they are very light weight though!
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Post by grizbach on Oct 7, 2014 7:35:07 GMT -8
Excellent job on those risers David!
This has been a good thread to follow!
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Post by PNW Dave on Oct 7, 2014 12:35:33 GMT -8
Some more pictures. I significantly reduced the dimensions of the clay brick box and plan for a viewing window in the burn tunnel. Also show a mockup to help visualize the design concept of a second barrel (half barrel is pictured) to reheat the final exhaust. The inner "standard" barrel will sit all the way down to floor level (everything on top of insulation of course) with a hole cut in the side for the burn tunnel to connect with the heat riser. This barrel will be topped with a hot water tank (not pictured) that is cut to fit over the heat riser with a sufficient gap. The outer barrel goes over the top of that-  Hot gasses exit the inner barrel through the back left side of the bricks and enter the dead-end, half-barrel bell, bench. Cooled gasses will enter the outer barrel directly, which sits on top of the core, not going through the bricks.  Viewing window in the side of the burn tunnel-  Playing with mortar color. Fire clay, silica sand and black concrete pigment-  And coloring the brick with the mortar using a quick wipe-on/wipe-off-  Fun! |
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Post by ericvw on Oct 7, 2014 14:20:27 GMT -8
Hey Deaks,
What kind of glass do u plan on using for the viewing window? Do u have a spare piece of ceramic glass laying about, or something?
I was thinking I read in that patent that steam would try to get away from the hot face, or did I read that somewhere else?! Anyway, sounds like your barrels need to go thru a few test firings to see if u achieve the desired results... Can't hardly wait to hear about it!
Keep up the thorough work and postings! As Grizbach said, this HAS been a good thread to follow...
Eric VW
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Post by PNW Dave on Oct 7, 2014 17:40:30 GMT -8
Excellent job on those risers David! This has been a good thread to follow! Thank you Griz! I'm really looking forward to eventually starting a new thread in the "Finishing and Finished" forum! Though I'm afraid it could be a while before the bench is finished, because I won't start that build until the core and half barrel bell is tested and tuned. Here is a link to my other thread, with more details on the concept for the bench- Feedback on my RMH concept wantedHey Deaks, What kind of glass do u plan on using for the viewing window? Do u have a spare piece of ceramic glass laying about, or something? I was thinking I read in that patent that steam would try to get away from the hot face, or did I read that somewhere else?! Anyway, sounds like your barrels need to go thru a few test firings to see if u achieve the desired results... Can't hardly wait to hear about it! Keep up the thorough work and postings! As Grizbach said, this HAS been a good thread to follow... Eric VW I plan to use ceramic glass, which I will have to buy. Last year we replaced both windows on the box stoves doors, only one of which was cracked... and I didn't keep the other piece of glass. DANG! So I will contact the place that we took the doors to, hopefully they have some old used pieces laying around for cheap. Sounds likely that steam would tend to move away from the hot face. When I burned each of the heat riser sections on my little 4 inch stove, the inside dried and hardened quickly while the outside takes hours to dry. I burned hot and fast, inside reaching 550-608F (max temp on my laser infrared thermometer) and the outside just getting to 140-150 after 3-4 hours. Video- (still uploading, coming soon) |
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Post by PNW Dave on Oct 7, 2014 21:15:31 GMT -8
Here is a video that shows the making of a heat riser section. Ramming the perlite mix, removing the form, and immediately starting a fire under it-
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Post by Daryl on Oct 8, 2014 1:20:02 GMT -8
That was cool.
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Post by PNW Dave on Oct 8, 2014 1:46:23 GMT -8
That's impressive, David, Very nice, well done and the video itself is really good! Your post indicates homemade water glass... Can u share the process? Thanks and can't wait to see what you cook up next! Eric VW Here is a video I made showing the process of making water glass. This batch was just the last of my ingredients, so not exactly sure of the amounts (about half of the usual batch). The usual batch was 1000 milliliters of water, 400 grams of lye and 600 grams of silica gel. This makes 1000 milliliters of silica gel (1+1=1), or less if you take too long, boiling away trying to get big chunks of silica gel to dissolve. Although, I have usually ended up with some extra silica gel, about 50-80 grams, by the time the mixture is getting pretty thick. Continuing to add silica gel past a certain point will make the water glass so thick, that once cooled it won't pour out of the bottle. Warming it will help get it to flow. I have combined and heated a batch that was too thick into a batch that was in-progress, seemingly without any problems. |
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Post by Daryl on Oct 8, 2014 2:25:32 GMT -8
"so don't do this" Ha! Another great video. Cheers.
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Post by wiscojames on Oct 8, 2014 5:57:43 GMT -8
David - good stuff! What are your thoughts on using this mix for a core. Seems pretty durable, and much lighter than a mix that uses much more fireclay. I see you've opted to go with firebricks instead. Just easier to build, or other reasons as well? Why didn't you burn out the inner form? To reuse it?
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Post by PNW Dave on Oct 8, 2014 12:31:02 GMT -8
"so don't do this" Ha! Another great video. Cheers. Haha! Yeah, a slight lack in patience causes a significant slow down. |
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