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Will an oven fit....looks like yes! PA build

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  • #46
    Originally posted by mk e View Post

    Joe
    I have no reason to quote anything you posted about lime....but like is not required below 500C so I don't think it matter if mortar has the right line or not.

    Mark
    My advice still stands for future followers. I can post pics of my own experiences with the wrong lime in fireplaces. They reach temps below WFO's.

    Good luck on your build.
    Joe Watson " A year from now, you will wish that you had started today" My Build Album / My Build

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    • #47
      More drinks ....my hands really hurt....

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      • #48
        Sounds like you have done everything that you can do with the gloves. Mineral oil is what we used to protect our hands. Some used vaseline or petroleum jelly. It will take a break for a few days for the hands to completely heal. Then try the mineral oil when you go back to work. Apply it before starting to work and after each break when you have washed your hands. Also, keep using the gloves. It takes a while to build up the hide for masonry work .
        Joe Watson " A year from now, you will wish that you had started today" My Build Album / My Build

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        • #49
          The weird thing is between the garage, patio, and oven I've been pouring footings, laying block, base coat stucco pallets or trucks at a time all year with no issues at all.....but this brand stucco literally dissolved my skin. Weird.....I still have a couple retaining walls to do and such.....I'll be wearing the up to my elbow rubber gloves along with the oil up suggestion...my hands and forearms are a mess, o put on about a dozen bandages this morning to cover all the holes.

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          • #50
            The last thing on the oven is to decide what to do for a cap. Lana's talking about having me build something with bricks so it matches....but what exactly that something is remains undefined.....

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            • #51
              ....but this brand stucco literally dissolved my skin. Weird....
              That is the signs and symptoms of having real lime in the mix.
              Joe Watson " A year from now, you will wish that you had started today" My Build Album / My Build

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              • #52
                Originally posted by mk e View Post
                David, There's a ton of data in that paper and that's the way I read it the first time though as well. On the 2nd or 3rd read I realized the the data is for concrete and when they say aggregate they mean the crushed stone in the concrete not the sand that is breaking down so that doesn't apply to mortar. On page 32 you'll find "The aggregate type is one of the main factors influencing the compressive strength of concrete at elevated temperature.". Up on page 20 is this "Results in the literature indicate that the primary factors affecting the modulus of elasticity at high temperature are the type of aggregate". so that's the stone that's burning out of concrete and not applicable to mortar.

                I think the most important part of the article is on p24:
                "Figure 25, which presents results for unsealed mortars fabricated from ordinary Portland cement, blast furnace slag cement, and truss cement, indicates little difference in strength-temperature characteristics, except the ordinary Portland cement mortar exhibited a sharper decrease in strength at temperatures greater than 500C (Ref. 4). Another study utilizing a number of cement types (e.g., ordinary Portland cement, fly ash, and blast furnace slag cement) also noted that up to 600C there was little effect of the cement type.52".

                Basically portland based mortar is good to 500C-600C, which is well above wfo operation temps which is why I agreed to building the dome with the cheap stuff and just pointing the inner 1/2" which could see higher temps with the high temp stuff.

                I'm not in ANY way saying its wrong to use the high temp stuff for everything, but I think there is data to support the use of the low temp stuff for most of the work and its cheaper and easier to work with....but in my case with the bricks fitting pretty well and all the mortar buried under the dome I'm not sure I'll ever know if the mortar burned out...I guess.

                The weather looks good for a couple days so I took a vacation day and tomorrow will be finish stucco coat day. There is still some question about what th finish will be. I'm pushing for a sponge finish so I know I can make the curves look nice but my house and garage are textured and Lana like things to match.....we'll see what tomorrow brings.
                As you rightly point out the failure of the OPC/sand mortar at higher temperatures may be attributed more to the sand and its thermal expansion affecting the bond with the cement paste surrounding it. The sand of course is simply a fine aggregate in itself.

                And this in the paper's conclusion ...Concrete in the temperature range of 20C to 200C can show a small strength loss. Between 22 and 120C any strength loss that occurs is attributed to the thermal swelling of the physically bound water, which causes disjoint pressures. A regain of strength is often observed between 120C and 300C and is attributed to greater van der Waals forces as a result of the cement gel layers moving closer to each other during heating. Between 200C and 250C the residual compressive strength is nearly constant. Beyond 350C there can be a rapid decrease in strength."

                The bottom line is that many before us have found the OPC/sand mortar inadequate, while the home-brew with the addition of lime and clay allows a higher service temperature and has proved to be a far superior and better suited material for both fireplaces and wood fired ovens.
                Kindled with zeal and fired with passion.

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                • #53
                  Originally posted by Gulf View Post

                  That is the signs and symptoms of having real lime in the mix.
                  lime it is then
                  "Quaker Stucco is a natural cementitious finish made up of white Portland cement, lime, aggregate, and pigment"

                  "CAUTION FOR INDUSTRIAL USE ONLY:
                  Wet cement, especially as an ingredient of a plastic mixture, can dry the skin and cause alkali burns....."

                  ...next time I'll put on my thick rubber sandblasting gloves that cover up to my elbows.

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                  • #54
                    Ouch, sorry about the chemical burns. This is a good lesson for all you prospective builders out there. Proper personal protection equipment (PPE) should be used when building the ovens. This includes dust masks or respirators, ear and eye protection, gloves, etc. An old timer said you can counteract the alkali (which is a base) by dipping your hands in vinegar (which is a light acid) after working with concrete or stucco.
                    Russell
                    Google Photo Album [https://photos.google.com/share/AF1Q...JneXVXc3hVNHd3/]

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                    • #55
                      Good advice Russell,

                      But, the use of vinegar to neutralize the lime has to be done immediately after exposure. Then go straight to a water source to rinse the area with copious amounts of water. It doesn't take but a very few minutes for a strong caustic to do it's damage. Hydrated lime is about 12 on the ph scale. If you get it directly on your skin for 15 to 20 minutes, the raw nerve endings are going to hurt like hell when the vinegar is poured on. It's best to not get it on you to start with. The gloves are the best protection. A second layer of protection (the oil) will help protect when taking the gloves off and putting them back on. My dad and uncles never wore gloves of any type when working with true lime mortar. They did this every day. Their hands were like leather. But, they put mineral oil on every morning and after breaks.
                      Joe Watson " A year from now, you will wish that you had started today" My Build Album / My Build

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                      • #56
                        Originally posted by Gulf View Post
                        Good advice Russell,

                        It's best to not get it on you to start with. The gloves are the best protection. A second layer of protection (the oil) will help protect when taking the gloves off and putting them back on.
                        Yup...long gloves that cover your wrists and forearms.

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                        • #57
                          Kind of just waiting for October now and finishing up other patio stuff in the mean time so its finished and ready for the first fire event. Got the back of the island stuccoed tonight.....with no new skin damage

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                          • #58
                            Feeling a little lazy today so I tackled a couple little things like cleaning up the stucco mess around the base, sanded the sharp corners off the brick and a quick acid wipe (wearing gloves! ).....looks better I think.

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                            • #59
                              It's been done for months so it should be dry I guess... 1st fire tonight. 1 small stick, cut to 6 or 8 bits and burned slow. First pizza is planned for Saturday.

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                              • #60
                                Im almost certain it wont be dry. Like a pile of sand that has been sitting for months is still damp in the middle, so will be your oven. Test this by throwing some plastic over it after youve had a fire in it for an hour or so. Condensation on its underside will tell you its not dry. Better to forget pizzas for now and use it to roast some chickens (around250C), or bake bread, much safer for your oven than shooting for the higher and potentially more damaging pizza temps.
                                Kindled with zeal and fired with passion.

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