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Thread: DIY Refractory Compositions

  1. #171
    Senior Member TopEndScraper's Avatar
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    Sep 2012
    Darwin ,Northern Territory, Australia
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    here's a link to the tutorial
    Is back on line

  2. #172
    Hello, I'm new to this forum and I work with glass, but about 40 years ago I did some work in iron foundries and so, being a pyromaniac, like to play in the arts of the fire. Anyway, I used to make stoppers and collars for glass furnaces - "D" shaped tiles 12" x 10" x 1.5" expendable shapes for sealing furnace mouths. Also gathering rings,that float on the surface of the glass. These things had to withstand some thermal shock, alkali batch dust, some slagging due to glass contact, and long periods at 1400 degrees Centigrade. The mix I used was 2 parts fireclay and 1 part Firebrick grog 1/8th" to dust. Mix with water and leave until stiff and pliable. Ram into wooden moulds lined with wet cloth, tip onto a board or concrete floor to dry. Once dry, warm at furnace and they are ready to use. The mix can be used for making your own custom designed blocks, bricks, burner ports, furnace lids, etc. Good for patching furnaces, or when building furnaces, as a gap filler, especially to stop flame ingress. It will shrink a bit, but if you don't need the plasticity, add more grog and it will shrink less. This is a hot face mix. It could easily be used for lining a crucible furnace or the like. In the foundries they used something similar called ganister - a silica rich clay, for patching up cupolas, lining metal receivers, bogies, ladles etc.

    Now I also have a question. I'm building a kiln and a small crucible furnace, using vermiculite with sodium silicate/CO2 binder as back-up insulation shapes. Can anybody advise on the proportion of Sodium Silicate/ Vermiculite?


    Bob the Slob

  3. #173
    vermiculite is really bad around foundry stuff, what you want is perlite. vermiculite is designed to hold moisture in the soil, so all it'll be is just a sponge for water/moisture in your lining, so it'll just pop and destroy the lining. perlite doesnt absorb the moisture, it's just there to airrate the soil and let more air get through it, which also makes it very good for refractory uses.

    I think ckindred on youtube had a setup like what your wanting, but they added a small amount of sandblasting grit/alumina to the mix too, here's the video

    I dont know how well that mix works, but it seems to be the closest to what your after.

  4. #174

    Vermiculite/Perlite with Sodium Silicate Binder

    Thanks for the info. ckindred (youtube video) used 4litres Perlite plus 350 ml Sodium Silicate and 350 ml water with some Alumina powder for his forge lining. (We use a similar gas fired "Glory Hole" for reheating when glassmaking -Drum lined with ceramic fibre).

    Anyway, I'm going to try a fireclay/grog shell about 1" thick. 1400 deg C ceramic fibre behind that and the vermiculite - or perlite and Sodium Silicate mix to fill the rest and gas it with CO2.

    If that works I'll try making slabs of the stuff for kiln walls. Its only going up to 700 deg C.


    Bob the Slob

  5. #175
    Good evening all,

    First post, but thought I would share my first mixture - a pretty simple one from a Youtube video from King of Random.

    10:10:6 of Plaster of Paris, Play Sand and Water

    Like a solid noob, didn't take into account the moisture content of the sand, so mixture was extremely wet (think soup...) On the Lid pour I just did equal parts PofP and sand with enough water to mix it through.

    The base was a 9L (I think?) metal pale, with a plastic pot plant inserted into the centre. Lump charcoal fuel with hair dryer providing forced air induction.

    Final product was good for only about half a dozen aluminium melts and two brass melts, became extremely fragile and crumbly - could be chipped away with finger nails, etc.

    Photos are after the unit was left out in the rain, once the decision was made to try a new mixture.


    Not 100% sure of the next mixture, thinking something simple like equal parts fire clay, perlite and fine sand (perhaps from an aquarium?), with just enough water to get it all together.

  6. #176
    ROTFLMAO.... Welcome anyways. If you're serious about metal casting allow me to introduce a book that is better material than the KOR.
    Visit me:
    "Sometimes by losing a battle you find a new way to win the war"
    -- Donald Trump --

  7. #177
    Senior Member schnelle's Avatar
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    Jan 2014
    Central Kansas
    I saw this material on a YT video. What uses could you get from it?

  8. #178
    Senior Member
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    Jan 2012
    Buffalo, NY
    Quote Originally Posted by schnelle View Post
    I saw this material on a YT video. What uses could you get from it?
    Probably limited to what it says in the product description. Mortar firebricks together or fill cracks.
    I was just given these pails of material by one of my printing customers. I print the labels for the pails. I'm not sure if he actually manufactures the stuff or not but I believe he does. I just asked him where they sell his products at retail the last time he was at my sales counter and he brought these in a couple days later. I still have to research them, but I'm sure I'll find them helpful in some way. I doubt they'll work as full-on refractory, but I have some ideas where they may prove useful.


  9. #179

    I'm aiming to construct my own alumina tube for a furnace.

    I want the tube to be 95- 97% Calcined Alumina and the rest, probably Calcium Oxide. Then I will wrap Kanthal A1 wire around it.

    The Kanathal handbookdry, advise a low "free silica" content to avoid damage to the element.

    "The free silica (un-combined quartz) content should be held low."

    I'm still not clear what that actually means. I am looking to follow this patent;

    where the binder consists of a wet or dry phosphate and silica sol or silica fume.


    A mixture of 1 volume 50% wt polyammonium phosphate is mixed with 4 volumes of 40% wt silica sol, the mixture is then mixed with tabular alumina grains and powders such as are readily known to users and manufacturers of ceramics at between 60 mls per kilogram to 80 mls per kilo and then placed in a mold.

    At normal working temperatures, 150 degree - 21 degree C, gelation occurs in approximately 30 minutes and can be removed within one hour. No accelerator in the form of a finely divided grain is used in this example; it appears that the silica sol causes the phosphate to gel as well as vice versa.

    This doesn't seem like free silica to me. So what kind of ingredients would result in a "free Silica"?

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