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  #161  
Old 04-15-2013, 06:38 AM
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Default Re: 36" Pompeii in DC

With the advent of spring, I've been doing a bunch of work on the oven (or rather, its surounds).

First, I re-built my door, such that instead of warped aluminum, the insulation is now sandwiched between two pieces of Hardiboard, with aluminum flashing for the edge, and a decorative wood front. The wood sits nicely flush against the inner reveal. Despite this, on my first use of the new door, the oven dropped from 550 to 300 overnight :P. I can't figure this thing out. I'm still getting the front of the oven feeling warm through the insulation and stucco--maybe there's still moisture being driven out?

I've also been working on the prep table next to the oven and countertops for the oven landing. Dry stacked concrete blocks for the support, bent rebar to go from corner to corner, then poured a 3.5" slab and filled the cores in one go. I got a small Harbor Freight cement mixer as a birthday present, and it made the work go fast.

Also poured a 24"x49"x2" slab for a polished concrete countertop to go on the prep table. The concrete mix ended up being way stiffer than I expected, yielding lots of voids, both because of air gaps and the fact that it pushed the crushed glass into clumps. Said clumps either had big voids around the edges of the glass, bigger voids where a bunch of glass fell out, or both. The attached picture is from after demolding and grinding with a 50 grit diamond pad. This weekend I went up to 400 grit and added (a lot of) slurry--hopefully it will smooth out and the filled voids will give it a nice veined effect.

I also have been working on countertops for the oven landing. Started by building up the landing so that a ~2" countertop would be flush with the oven entry. Did this by mortaring in bricks along the edge of the structural slab, and then pouring concrete into the enclosed space once the mortar had set. Then I screwed the forms for the main countertop into the bricks using masonry anchors. Poured the countertop yesterday after the last picture was taken--I'll start polishing this weekend and hope for the best.

Now that the work surfaces are nearly done, I'm planning on a big pizza party for early May
Attached Thumbnails
36" Pompeii in DC-img_7761.jpg   36" Pompeii in DC-img_7760.jpg   36" Pompeii in DC-img_7764.jpg   36" Pompeii in DC-img_7762.jpg   36" Pompeii in DC-img_7763.jpg  

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  #162  
Old 04-15-2013, 09:34 AM
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Default Re: 36" Pompeii in DC

Nice to hear from you. The weather must be considerably nicer in DC than here in MI. What is the advantage of placing your countertop in a separate form vs formed onsite? I know it can be done both ways but I haven't heard or read a convincing Pro/Con comparison of the two techniques. Knowing that you always do your homework first, I wonder what you have found.

Always look forward to seeing progress on your project. Nice work...I think the blue glass/cement countertop will look spectacular when finished.

Regards,
AT
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  #163  
Old 04-15-2013, 10:08 AM
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Default Re: 36" Pompeii in DC

AT: Spring was somewhat slow in coming (or so I am told by my co-workers who have lived here longer), but it has been lovely the past few weeks. Highs in the low 70s all weekend.

On the countertop forms, I dithered back and forth a lot, and in the end the deciding factor was idiot-proof-ness. Pouring "face down" in a form gives you a smoother surface before you start polishing and gives you more control over shape and size--it's much cleaner and more straightforward to have the countertop make a slight overhang, for instance. Although my slab ended up pretty craggy because of the stiff mix, the bits without glass bear out the argument about smoothness--if you were okay with a matte surface, you could probably skip polishing entirely.

In principle pouring face down would help the placement of decorative aggregates like the glass, although that didn't work out so well for me :P. All this meant that for the prep table, which was just a simple rectangle, pouring in a form left the least room for error.

For my landing counters on the other hand, I had a much more complex shape, since I wanted the counters to fit around the vent area and wrap around the sides of the igloo. Possible you could build a form to do this, but I would surely mess that up. I was also paranoid about getting the countertop the right thickness--I wouldn't want the countertop to go above my entry bricks. As a compromise on getting the countertop to do a nice overhang, I screwed a 2x4 to the bricks in the front and mounted the melamine form on that, while the side pieces are screw directly into the brick.

If I had an enclosure (and thus was doing just a simple rectangle for the landing counter), I would have done a face-down pour for both, but this seemed like a pretty good compromise.
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  #164  
Old 05-02-2013, 06:40 PM
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Default Re: 36" Pompeii in DC

Lots more work on the counters. Pics attached for the prep table.

This didn't turn out at all how I expected, but I'm really happy with the results. The bright orange color of the slurry was the result of me mistakingly thinking the slurry would lighten as it dried. Word to the wise: slurry made with white portland cement does not change color when it dries. Live and learn... Still, the brown/orange/blue mix, actually works. As my wife put it "I know that wasn't what you were trying to do, because I can't imagine you trying for orange, but it actually looks pretty cool."

I shelled out for the Cheng brand sealer, which after two coats keeps moisture out of most of it. Also applied a very thin coat of Cheng wax before I got fed up with the cheap buffer bonnet I bought and called it good enough. I did discover that after a couple days of constant, drenching rain there were a few spots that "wet out" despite the sealer. Wondering if I should buy another bottle of sealer and re-seal, and if that will even work through the wax. I guess if water gets through, the sealer should too, right?

Pics of the landing counter to follow...
Attached Thumbnails
36" Pompeii in DC-img_7764.jpg   36" Pompeii in DC-img_7767.jpg   36" Pompeii in DC-img_7768.jpg   36" Pompeii in DC-img_7799.jpg  
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  #165  
Old 05-02-2013, 06:49 PM
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Default Re: 36" Pompeii in DC

And here's the landing counter, pics attached.

I'm satisfied with how the landing turned out, but not nearly as happy as with the prep table slab. If I had it to do again, I'd have figured out some way to pour it face down. In part because it was hard to screed and in part because I'm a lousy hand with a trowel, the initial surface was very rough, and uneven to boot. Even after two slurry coats, there were still a bunch of dings and divots that I just gave up on. On the other hand, I can already see that the landing will frequently be coated in ash and gunk from the fire, so maybe I shouldn't worry about it too much.

I ended up continuing the orange them here, although again unintentionally. This time I knew that whatever color the slurry started would be the color it stayed, but the slurry looked browner in the mixing tub, and turned orange as I started rubbing it in :P. Ah well, now I've got a them. And it goes with the terracotta red flue tile. If I admitted that I goofed on the color, you'd think I planned it.

I guess now the tile mosaic for the dome will need to use those colors: brown, orange and flecks of blue. Any suggestions on designs?

The finished product:

Attached Thumbnails
36" Pompeii in DC-img_7770.jpg   36" Pompeii in DC-img_7777.jpg   36" Pompeii in DC-img_7802.jpg  
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  #166  
Old 05-02-2013, 07:01 PM
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Default Re: 36" Pompeii in DC

Also, some better pictures of the working parts of my new door:





To put it together, I clamped the hardiboard and CalSil to the wood, and drilled holes through the board and insulation just deep enough to make a mark on the wood. Then I took the whole thing apart and used a countersink bit to make recesses in the wood for the bolts. Next, I put 3" SS bolts through the outer piece of hardiboard and lined it up with the recessed holes in the wood, and used hardibacker screws to screw the cement board to the wood. As a result, the outer piece of hardibacker is flush with the wood, but the wood is not in direct contact with anything that will face the heat of the oven. Well, there's probably some contact with the heads of the bolts, but not much. The handles are then screwed just into the wood, and never get hot.

Then I put the CalSil onto the bolts, used some pumpable ceramic insulation to fill the holes from the first incarnation of the door, and then put the inner piece of hardiboard on and tightened the nuts to hold the whole thing together. As a finishing touch, I used the pumpable ceramic to cover up the ends of the bolts to reduce the amount of heat transfer.

The oven rope in the pictures is not actually attached--I stuck it on over the weekend as I was slow-roasting a brisket, to see if it would help with the heat loss I've been experiencing. No idea if that worked, but it seemed content to stay put, and I haven't gotten around to adjusting it and cementing it down.
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  #167  
Old 05-03-2013, 06:36 AM
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Default Re: 36" Pompeii in DC

Looks like the wood is getting a little hot near the top and lower corner...

Chip

Last edited by mrchipster; 05-03-2013 at 06:39 AM.
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  #168  
Old 05-03-2013, 06:48 AM
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Default Re: 36" Pompeii in DC

Quote:
Originally Posted by mrchipster View Post
Looks like the wood is getting a little hot near the top and lower corner...

Chip
Yeah; I guess that's a good start for where the door may not be sealing well. Hopefully it doesn't do much more than char.
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  #169  
Old 05-03-2013, 07:35 AM
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Default Re: 36" Pompeii in DC

Quote:
Originally Posted by rsandler View Post
Yeah; I guess that's a good start for where the door may not be sealing well. Hopefully it doesn't do much more than char.
Be prepared for it to burn; char will easily turn to burn at some point. And highly likely after placing the door on after a long hot burn like a large pizza party.

I placed my decorative wood face on metal and cut it back so it is protected by the insulation layer and metal

Note that I still get heat coming thru the door and heating the area around the handles. The door is filled with 4 inches of ceramic board. The handle supports do go all the way thru to the interior so there is some heat loss there. Something I will fix at some point.


Chip
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  #170  
Old 05-13-2013, 12:18 PM
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Default Re: 36" Pompeii in DC

Ironically, the wood is holding up so far, even after two long, hot burns for a pizza party this weekend (a pre-heat the day before, then a long fire the day of). The cement board, not so much :P



Not sure what happened here; some chips of cement board had broken off previously and somehow wedged between the inner piece and the insulation, forcing the board away from the insulation. When I tried to fish the bits out last week, the board cracked a little bit. This weekend, I turned the door upside down to try to shake the bits out, and the sections of board cracked and fell off instead. The top piece that's cracked in the picture broke off shortly after.

What happened here? The cracks run between the bolts (and the top bolts are still partly holding the board on, a result). Did I tighten the bolts too much? Is cement board not suitable for these temperatures? The cement board-CalSil sandwich is what FB recommends in the Pompeii plans, though it seems that hardly anyone does it. Was the board just damaged, and once it chipped and the chips got wedged into it, the thing was doomed?

More to the point, how do I fix this thing? Start over? Just replace the inner board, don't tighten the bolts as much? Cover the exposed area with homebrew mortar? Could also parge the whole surface with homebrew, I suppose. I still have a bunch pre-mixed homebrew sitting in my garage. Just leave it? The insulation is still mostly covered by the aluminum tabs, the tabs are held down by the remaining cement board, and the bolts continue to hold it all together...so far.
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