?? DIY Ceramic Mold Coating for Cast Iron ??

Discussion in 'Castings, finishing/ repair/ and patina's' started by Dazz, Sep 8, 2021.

  1. Dazz

    Dazz Copper

    I am interested in what is possible to achieve the highest quality surface finish for cast iron in the back yard.
    An obvious focus of attention is ceramic mold coatings. I have seen USA suppliers named on the forum with the caveat that they are often reluctant to sell in small quantities to a DIY foundry. In my case, there are no suppliers in-country and the cost of shipping is prohibitive.

    There are suppliers in China that do sell suitable ceramic powders in small quantities and reasonable shipping rates. I have not found ceramic mold coatings for cast iron. So the purpose of this thread is to identify a source of ceramic mold coating for the DIY cast iron foundry.

    It is very likely that the "source" will be a recipe of readily available materials to produce a DIY coating. The best source of information needed to identify a recipe is going to be from those who have the money and resources to undertake research that they are willing to publish. Specifically universities.

    So the first objective of this thread is to gather research papers on ceramic mold coatings. To kick things off, I have found and attached a research paper: Ceramic Coating for Cast House Application from the University of Belgrade, and Institute for Technology of Nuclear and Other Mineral Raw Materials.

    Attached Files:

  2. Melterskelter

    Melterskelter Gold Banner Member

    What are you casting? What are you getting for finish using your current method? Pics.?

  3. Dazz

    Dazz Copper

    Here is a paper that reviews the range of coatings.

    Initial readings indicate the key ingredients are:
    refractory: Zircon powder or similar heat resistant coating
    binder: to hold the refractory in-place long enough for the metal to cool and to adjust viscosity. Sugar or Sodium Silicate are options.
    carrier: alcohol is common but water may be better for a number of reasons.
    dispersant: to prevent clumping of the insoluble ingredients
    biocide: to stop fungal and bacterial growth in storage

    Attached Files:

  4. Jason

    Jason Gold

  5. Dazz

    Dazz Copper

    None of that is available where I live.
    Many of the industrial coatings are alcohol or hydro-carbon based. That makes them heavy and classified as dangerous goods. Both = $$$$ for shipping costs.
    Shipping anything across an ocean is now too expensive and too slow. I have just received an item 4 months after buying it on e-bay.

    I think there is enough published research to make a reasonably good DIY mold coating with readily available dry and safe materials. That includes Zircon powder from China.
  6. Jason

    Jason Gold

    No R&R in Nz? Color me surprised.
  7. Dazz

    Dazz Copper

    The DIY recipe is starting to look like:
    • refractory: Zircon powder from China
    • binder: 1% to 2% Sugar or/and Sodium Silicate
    • carrier: water
    • dispersant: (anti-clumping) drop or two of dish washing detergent
    • biocide: nothing with Chlorine

    I have also found other info to help produce better castings. These include:

    Add a cover on the crucible in the furnace to reduce the flow of hydrocarbons (unburned fuel and CO2) oxidizing and contaminating the melt.
    The the pot lid type cover includes a hole, this could be used to read the black body radiation for accurate temp measurement.

    Ceramic filters to catch bi-films and debris
    Last edited: Sep 27, 2021
  8. Fire Bricks

    Magnesium chloride, magnesium oxide, vaporized silica, water and high compression.
    Last edited: Sep 27, 2021
    Dazz likes this.

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