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Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

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  • thickstrings
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    RSB, I can't tell from the picture, What type of heater is it....Mass? Bell? Other? I have made a few simple ones, and I am convinced that it is the way to go for my shop heater...I am leaning towards the bell type, but can't get over the core price....and the chiminey tile price...so I guess I'll keep feeding "Old Smokey" Making one is far different from producing them for sale... Good luck to you! edit...Don't know if this will work, http://www.skylinecomponents.com/Cer...ercoating.html but I have thought to use this over CF board in the heat riser section.....could be viable, just heat and no mechcanical abrasion...
    Last edited by thickstrings; 10-31-2013, 07:10 AM.

    Leave a comment:


  • RocketStoveBuilder
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    stonecutter,

    agreed, portland cement is not suitable for our application. Thanks for your caution.

    We used calcium aluminate cement found in Rutland's Dry Refractory Mortar Mix . We are experimenting now, as mentioned above.

    I've also contacted Rutland for their input.

    Be glad to share what we learn and post photos, here and on our website when finished, along with the results.

    Leave a comment:


  • stonecutter
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    I have never worked on developing a homemade a refractory mix design, but I can tell you that using portland cement ( component of the 3:1:1:1 mix) for your application would not be a good idea.

    It doesn't appear that you have though. Pics of your test brick would be cool.

    Leave a comment:


  • RocketStoveBuilder
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    "I think that anyone who comes on here looking for advise (sic) from members so they can use it in a commercial environment and hence make money is rude and cheeky. Are you going to split the royalties with the forum members for their effort, I doubt it. Go and pay a thermal engineer to come up with something to your requirements."

    I guess there is another way of looking at our requests: pretty tough trying to start a business in this economic environment, but we are doing our best with limited funds. All the advice offered was voluntary, for which we are very thankful.

    Looks to me that Forno Bravo is a commercial enterprise: from their website: "Italian brick pizza ovens for the home and garden, restaurants and pizzerias; wood and gas-fired. Outdoor masonry fireplaces, and accessories, including oven .." thus I saw no problem with seeking advice from those involved here.

    And yes, I would be glad to share the money we make with anyone willing to help us get a solid product on the market. Would you like to be involved? I won't even ask that you share in the expense of the shop, the equipment, or the time and effort we spent since May getting this endeavor off the ground. PM me and lets discuss your participation.

    Taking wotavidone's advice, along with a few others, we mixed a batch of fireclay, perlite, silica sand and refractory cement yesterday - made two bricks - each with different mixes. After proper curing on the stove itself, we'll place the bricks in the stove to see how they hold up.

    Today we intend to make a 4" thick slab more in line with our needs.

    Again, thank you to everyone who has offered their suggestions.

    Leave a comment:


  • brickie in oz
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    I think that anyone who comes on here looking for advise from members so they can use it in a commercial environment and hence make money is rude and cheeky.

    Are you going to split the royalties with the forum members for their effort, I doubt it.

    Go and pay a thermal engineer to come up with something to your requirements.

    Leave a comment:


  • wotavidone
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    When all is said and done, the 3:1:1:1 (sand:lime:clay:Portland cement) is very very cheap. So, very little money will be put at risk by making a stove lined with it and trying it out.
    Same can be said (nearly) for a refractory made with Calcium aluminate cemet (ciment fondu).
    Ditto any combination of perlite and cement you can think of, if you need some insulating qualities.

    Looks like you are going to have to do some research.

    Leave a comment:


  • RocketStoveBuilder
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    30% Ciment Fondu (calcium aluminate cement I'm sure you can get some)
    60% Aggregate (#6 mesh -sizing 3mm down to powder)
    5-10% Fine Sand
    5-10% kyanite (crushed, Metamorphosed peri-aluminous sedimentary rock, optional, if not available locally-add more fine sand)

    Awesome Lburou. I'll need to add perlite to the mix to get the insulative properties we need.

    Leave a comment:


  • RocketStoveBuilder
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    I think he is basically making one of these Wood Burning Heater - Dragon Burner Which uses a cast refractory. ? for O.P. How is the 8" clay holding up? what type insulation are you using?

    Yes.

    The 8" masonry flues seem to work fine.
    We use perlite for the insulation.

    Leave a comment:


  • RocketStoveBuilder
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    Thanks for your helpful replies.

    "Not sure quite what you are chasing, is it for thermal mass or for insulating?"

    The burn chamber and the "chimney" need to be able to withstand high heat, that is, they are hot faced, and need to be insulating at the same time.

    "You also need to add fibres to the mix to reduce the possibility of the refractory blowing when first fired."

    I've seen fibers added. What kind of (locally available if possible) fibers could be added? Shredded fiberglass insulation?

    My understanding is a low heat slow fire is how this ""blowing" is avoided, with a gradual increase in the temperature of the fire to cure the cast.

    "If money is a big issue, maybe you could line the firebox (the bit subject to impact and abrasion) with the commercial stuff and experiment with homebrew chimney linings?"

    That is an idea worth pursuing wotavidone.

    Money is an issue only in that the commercially available castables, if used, would constitute over 20% of the retail price of the finished product. We'd either have to forego that revenue or raise prices. An in house mix that would accomplish the same end - durable and insulative and less expensive is what we need.

    The product itself is not the real problem, it is the shipping that is almost the same cost as the product is the real obstacle.

    "You could make an insulating layer with perlite and clay and maybe Ciment Fondu (calcium aluminate cement not Portland) ..."

    Yes, just learned that calcium aluminate cement is what we want, not Portland cement - thanks for your excellent advice.

    "If you are going into production, you can buy the proper ingredients to make your own refractory castables."[/COLOR]

    Yes, that would be an excellent solution. Looks like I'll have to seek the input of someone knowledgeable about the "proper ingredients" or simply bite the bullet and use the commercially available products.

    Anyone know of a knowledgeable engineer or chemist - willing to assist us? If so, please PM me.

    Thank you david s, michelevit, wotavidone, Tscarborough and stonecutter for your thoughtful comments.

    Leave a comment:


  • Lburou
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    During a visit to my local refractory, I spoke with the owner and his engineer about a home made castable for my best friend working overseas where materials are not readily available. This is the home brew recipe they gave me -use at your own risk:
    30% Ciment Fondu (calcium aluminate cement I'm sure you can get some)
    60% Aggregate (#6 mesh -sizing 3mm down to powder)
    5-10% Fine Sand
    5-10% kyanite (crushed, Metamorphosed peri-aluminous sedimentary rock, optional, if not available locally-add more fine sand)

    HTH

    Leave a comment:


  • thickstrings
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    I think he is basically making one of these Wood Burning Heater - Dragon Burner Which uses a cast refractory. ? for O.P. How is the 8" clay holding up? what type insulation are you using?

    Leave a comment:


  • david s
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    Not sure quite what you are chasing, is it for thermal mass or for insulating? Any addition of insulating aggregates like perlite or vermiculite drastically weaken the resulting mix. You also need to add fibres to the mix to reduce the possibility of the refractory blowing when first fired. Use a proprietary mix and get advice from your refractory supplier as to the best product for your application.

    Leave a comment:


  • michelevit
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    I've made a wood fired pizza oven using the homebrew recipe of portland, fireclay, lime, sand, sand, sand. Its survived many years and has not signs of failure. I recomend it highly.
    No need for expen$ive castable refractory when the homebrew works just fine. Ours was cast over a sand mold similar to the clay ovens.

    Leave a comment:


  • wotavidone
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    You could make an insulating layer with perlite and clay and maybe Ciment Fondu (calcium aluminate cement not Portland) but I sincerely doubt that it would be anywhere near as robust as the comercially available castable.
    If money is a big issue, maybe you could line the firebox (the bit subject to impact and abrasion) with the commercial stuff and experiment with homebrew chimney linings?
    The 3:1:1:1 mortar mix used extensively on the forum for building ovens is not insulating, and I imagine a rocket stove could subject it to more heat than an oven does - I wouldn't use it in your application.

    Leave a comment:


  • Tscarborough
    replied
    Re: Your Advice Re: HomeBrew Castable Mix Greatly Appreciated

    It is not worth the expense and effort for a one-off, just buy the castable refractory. If you are going into production, you can buy the proper ingredients to make your own refractory castables. The homebrew as used on this forum is for mortar NOT as a castable.

    Leave a comment:

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