36" in Seattle

[kebwi]

Re: 36" in Seattle

Hmmm, so I should decide on my final approach before proceeding then, since presumably I would add the (feris?) oxide powder to that instead of the SBC and leave the SBC uncolored?

[Tscarborough]

Re: 36" in Seattle

"Ferrous". One or 2 coats of SBC and a finish coat of Thoroseal and it will be bulletproof.

[kebwi]

Re: 36" in Seattle

Actually, the stuff I bought is described as iron oxide, not ferrous oxide:

CONCRETE COUNTERTOP COLOR PIGMENT CEMENT IRON OXIDE - eBay (item 120469550837 end time Apr-11-10 23:31:34 PDT)

However, while ferrous has a specific chemical definition that distinguishes it from "ferric", it is also a catch-all term for "iron", so I think this is the same stuff you were talking about.

[Tscarborough]

Re: 36" in Seattle

It is. Ferrous=of or relating to Iron for general usage.

[jerrycook]

Re: 36" in Seattle

Might be your oven hasn't fully cured yet. Every time I fire my oven, The floor temp comes up 10 - 15 degrees. I've been making dough with bread flour and it cooks better than the Caputo at the beginning of a firing. I also make a batch of Caputo dough that I use last. My last firing, I had pizza cook really fast. I wasn't quite ready for it. Good though.

[kebwi]

Re: 36" in Seattle

Poured the counter, 8x80lbs Sakrete, about 4" deep (the oven floor is 5.5" above the hearth). The plan is to finish the counter with 1/2" granite tiles.

For those following my thread from the beginning, I mixed the concrete *MUCH* wetter than ever before (actually, I did the same thing last week when I filled the cores of the side wall). It still didn't finish with the float to a "glass-like sheen", but it is very wet, soupy, and dense (and had significant pools of water sweating up and wiping off). I'm satisfied with it (speaking only hours after the job, we'll see what I think later this week when the forms come off).

The astute observer will notice a small lip along the front edge relative to the front face of the hearth and stand, the width of a 2x4, so about 3.5".

Cheers!

[ThisOldGarageNJ]

Re: 36" in Seattle

Hey Keb,,

Did you float all your concrete with a piece of wood ?? or are you just screeding off the excess in the pic ??
Mark

[fxpose]

Re: 36" in Seattle

Looking really good. I've always admired the shape of that front arch. I like the shape of that counter too. Very practical design.

[kebwi]

Re: 36" in Seattle

Did you float all your concrete with a piece of wood ?? or are you just screeding off the excess in the pic ??
Mark

That pic isn't me "floating". I have a real float. Here's a photo of me pretending to use it on my ridiculously dry hearth:
http://keithwiley.com/pictures/brick...5-floating.jpg.

I was using that 2x6 to pack the concrete down a little and sort of screed the concrete. I say "sort of" because without opposing form walls I can't properly screed. One side of the counter runs up against the side of the oven if you see what I mean.

[david s]

Re: 36" in Seattle

Keith,
Be careful about adding too much water, it is a major cause of excessive shrinkage and results in a weaker product that is more prone to cracking. It seems like a good idea to add more water to make the stuff flow and easier to get air bubbles out. To reduce the water content, but retain fluidity use some plasticiser or add some detergent. Only add sufficient water so the mix becomes easier to turn over.
Dave

[ThisOldGarageNJ]

Re: 36" in Seattle

Keb,,

The reason I ask is this..

it should be floated with a wood or metal hand float. This embeds aggregate particles just beneath the surface; removes slight imperfections, humps, and voids; and compacts the mortar at the surface in preparation for additional finishing operations. Where a smooth, hard, dense surface is desired, floating should be followed by steel troweling. Troweling should not be done on a surface that has not been floated.

It looks like your using a wood float in the new pic,, May be why your not getting the finish you want...

Did you finish using "metal" ??

[kebwi]

Re: 36" in Seattle

Keith,
Be careful about adding too much water, it is a major cause of excessive shrinkage and results in a weaker product that is more prone to cracking.
Dave

Yeah, this one may have been done a little too wet, unlike the foundation and hearth, which were too dry (it's hard to hit that sweet spot). I must confess that my thinking was along the lines that since the counter doesn't need to be particularly strong (there will never be any load resting on it, and it is itself supported by the hearth over much of its area) that strength was slightly less crucial than for the foundation and hearth.

That said, cracking would still be undesirable (it doesn't matter aesthetically since I will be covering it with granite anyway, but nevertheless, your point is taken)...and all other things being equal, one would generally want to "do it right" just for its own sake.

Hope I didn't ruin it, and I really hope it doesn't suffer structurally (chip, dip, buckle, sink, collapse, etc.). Clearly, there's nothing I can do about it now.

BTW, that's 3/8" rebar. I used 1/2" for the foundation, primary wall cores, and the hearth, but only 3/8" for the cores of the additional side wall and the counter, including over the suspended area. Hope that's okay. If I anticipate a serious problem in advance, I can put more vertical support into that small triangular area on the left, but it would be nice to see the need coming in advance, if you get my meaning.

Thanks for the advice.

[kebwi]

Re: 36" in Seattle

It looks like you're using a wood float in the new pic, May be why you're not getting the finish you want...

Did you finish using "metal" ??

That "new" pic is from the hearth, so it's pretty old. Um, yeah, I admit that wood is not suppose to finish as smoothly as magnesium. I don't particularly care since I intend to cover the whole thing in granite anyway. In fact, a rougher surface might bond to the tile thinset better. I'm just not sure how one would go about achieving a smooth finish if one wanted to; it's hard to believe that magnesium would make that dramatic a difference relative to the results I've achieve thus far...but all that aside, I readily admit that one critical component to getting a smooth finish is using the proper float in the first place, i.e., magnesium.

[fxpose]

Re: 36" in Seattle

I was using that 2x6 to pack the concrete down a little and sort of screed the concrete. I say "sort of" because without opposing form walls I can't properly screed. One side of the counter runs up against the side of the oven if you see what I mean.

Using a longer screed would have enable you to bridge across between the form walls.

[kebwi]

Re: 36" in Seattle

This weekend I took the forms off the new counter. I am quite pleased with it. It is very dense concrete, not necessarily butter smooth on top (which I only floated with wood, not magnesium, but very solid, and the under-face and sides are extremely smooth where the (too) high water content really creamed up against the forms.

Maybe it'll crack to pieces from being mixed too wet, I dunno.

Then I started stuccoing the oven with surface bonding cement. I was not prepared for just how bizarre the stuff is. It is truly weird. The work is quite a bit slower for me than I imagine it is for most applications because I have to work it over those numerous strange edges and corners, many of which are concave. I think stuccoing the large exterior faces will actually go much more quickly. If you look closely, you will notice that I stuck on little drain-aways at many of the weep-holes with the intention of letting water drip into the planter beds instead of running down the stucco (behind the eventual plastic liner and under the planter beds).

Also, I applied most of the talavera tiles with Liquid Nails. Just a few more to go.