Walker Core Variation

[DCish]

Thanks for the links, I'll go take a look.

As for the IFB, having seen what you've done with that and now with ceramic fiberboard, I am much more comfortable with the idea of it now than I used to be. Who knows where I may end up!

[independentenergy]

how you intend to implement the secondary air duct?

[DCish]

Well, I haven't quite figured that all the way out yet. Right now I have a 1.5" steel pipe ending just as the port begins. I figure I'll put a 90 elbow so that it sticks more or less into the port at the near end in the short term. Long-term it'll take some more thought. Likely a walker-type floor channel ending mid-port, I'd think.

[DCish]

Jan 25, 2017 8:46:11 GMT -8 matthewwalker said:

DC, a fella over at Permsteading was playing with whole builds of super wool a few years back. Here's a link to the last iteration. If you search that user or BOOH you'll find more ideas for your wool. I think it works fine, but is permeable, so I believe it isn't a great choice on it's own.

www.permsteading.com/viewtopic.php?f=6&t=338

I suspect you are over estimating the IFB wear. Try it. They work great, and it will take a long time to wear one to the point of being a worry. At which point your other ideas are still valid.

Another thought: I could just use IFB, and after it gets nicked up a bit, I could use a "hard" mix such as the guy in the post you linked to is using, or that other folks are experimenting with, and "paint" a few layers of it on to make a hard over-layer that I could touch up if I ever felt the need. And given your positive experience with IFB, I may never need to even do that.

[DCish]

walker - what firebrick temp rating did you use when playing with IFB? Do you think 2000 degree F good enough? Seems to me that would be fine since this wouldn't come near the temp of a forces-air forge, I'm guessing.

[matthewwalker]

I'm not sure DC, they were given to me from a kiln tear down. They are white, and extremely light, <1lb. And yeah, if they get bad enough to worry about over time, then we can figure out a liner or insert. It will take a while.

Oh, edit: Temp rating in my experience is a function of density, so I'd go for the lower rated ones. 2000 sounds good. They won't melt no matter what the rating.

[DCish]

Ah, valuable tip on the density, thanks.

[matthewwalker]

I could totally be wrong, ask your supplier if you can. It works that way with the castables I've used.

[Vortex]

The insulating Refractory Bricks I got recently are incredibly light. The first one I picked up I almost ended up throwing across the room because I expected it to be a lot heavier than it was. You can see why if you look closely at the surface of them, it's made up of thousands of air bubbles about 1 to 1.5mm in size. The supplier has them down as being made of Alumina and silica, I guess their using some kind of foaming agent to get the air into them.

They're quite soft, you can just about scratch the surface with a finger nail and leave a mark. Easy to work with as you can saw them with a plain wood saw. Haven't tried them out in a stove yet, but the temp rating is 1200*C / 2190*F.

[DCish]

Okay, I'm liking the idea of playing around with trying to make a hard coating on insulated firebrick. So far my ideas are trying water glass, and clay slip. Anybody else have ideas on things to try?

[dan0]

Jan 27, 2017 13:59:12 GMT -8 DCish said:

Okay, I'm liking the idea of playing around with trying to make a hard coating on insulated firebrick. So far my ideas are trying water glass, and clay slip. Anybody else have ideas on things to try?

Has anyone tried troweling on some castable refract..?  It might be better to let the bricks wear a bit to help with a better bonding surface.  Just thinking out loud here.

[wiscojames]

I applied a layer of fireclay inside my 'mud' batch box, and it helped protect the interior for a good long time. An eighth inch, probably.

[DCish]

After some research, the nearest refractory supplier is over an hour away. Since time is my enemy, I bit the bullet and ordered a single brick online. I figure I'll cut it into sections and test a couple of different ideas for abrasion resistance, and let you all know how it comes out.

dan0: I don't have any castable refractory, but I seem to recall seeing some approximate recipes around. Maybe there is something I can dig up to come close. I also need to return to Karl's geopolymer thread and see if I have the ingredients for a small batch of the stuff he cooks up.

Probably it makes sense to try a mortar mix as well, such as Walker's 3:1 sand:clay mix.

wiscojames: Thanks, that's good data. I'll make a fireclay slip and build up a layer on one of the test sections.

[matthewwalker]

My opinion is you are way overthinking this DC. If you test a little piece you are going to turn it into powder in a second.

[Vortex]

DC, Castable refractory mixes are mostly made from material that has been fired to a very high temperature and crushed to 3mm or less, it's known as 'grog', and a high temperature cement like Ciment fondue.

My local supplier has a bit on their website that says "Firebrick is made from crushed firebrick" - which begs the question where did the first firebricks come from?

One sack of castable I had last year contained some bits that had escaped the crusher and so were easy to identify, these included bits of electrical ceramic insulators and pieces of old clay red bricks, and Lots of bits that looked like porcelain.

I homemade some last year from old crushed fired clay roof tiles sieved through a 3mm screen and mixed 5-1 with ciment fondue. I also made some from my local clay which is mostly Alumina & Silica screened down to 3mm and mixed with the ciment fondue. The local clay one has done 4 months in my firebox and is still perfect.

Anyway, some idea for you.