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Wax that never burns -- Is that possible?

  1. Jun 14, 2017 #1
    Dear all,

    I am an artist and I am making a sculpture in wax that melts using an electric system.
    I know that wax ignites fire in a temperature of 200°, but, because it is an exhibition with public, I wanted to be completely sure that it does not take fire, in any temperature.

    Do you know if I can mix something to it in order to prevent fire, or at least to make the ignition temperature much higher as 200°?

    Thank you so much for your answer!
    all the best

  2. jcsd
  3. Jun 14, 2017 #2


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  4. Jun 16, 2017 #3
    thank you very much! I will have a look.
    All the best! :)
  5. Jun 16, 2017 #4


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    That is a good start.
    Thinking more about the problem; For health reasons I would avoid flame retardants that contain chlorine, flourine or bromine compounds. Also avoid the phosphates.
    I would look at aluminium, magnesium and boron hydroxides that are well known as flame retardants.
    When they decompose at higher temperatures, they absorb energy and produce water.
    Each decomposes at a different temperature, so you have some choice.

    Aluminium hydroxide decomposes at 180°C. 2 Al(OH)3 → Al2O3 + 3H2O

    Boric acid decomposes at 236°C. H3BO3 → HBO2 + H2O

    Magnesium hydroxide decomposes at 332°C. Mg(OH)2 → MgO + H2O

    Heating sodium bicarbonate releases water and carbon dioxide.
    Decomposition starts at 80°C. 2 NaHCO3 → Na2CO3 + H2O + CO2

    You might also consider adding commonly available Borax to the wax.
    But don't be surprised if you end up with some form of wax that bounces.

    I am not a chemist so I cannot say what will happen when you mix these materials with hot wax.
    Decomposition temperatures may be dependent on the type of wax.
    The density of hydroxide needed in the wax may be critical to extinguishing a flame.
    Some of these hydroxides may melt in the hot wax and mix or separate.

    Does anyone else have any ideas?
  6. Jun 16, 2017 #5


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    What kind of wax are you using? And what kind of heating system are you using? Paraffin wax typically melts at around 40-50°C, which is nowhere close to its flash point of 200°C (which is the temperature at which the wax ignites if a flame is applied). The autoignition temperature (the temperature at which a substance ignites spontaneously without an applied flame) of paraffin is 245-340°C per the MSDS:
    So fire concerns really depend on how you're melting your sculpture. Chances are you'll have a big puddle of melted wax long before you get it hot enough to ignite.
  7. Jun 21, 2017 #6
    Hello TeethWhitener,
    thank you for your message,

    I still didn't buy it but will certainly use paraffin, because it is cheaper. And mix it with pigments.
    I've been searching a lot for a source of heating, from film pads used in cars to normal home heaters.
    But it has been difficult to find something that stops at 100°… that is why I thought about a flame retardant, just an extra security measure.
  8. Jun 21, 2017 #7


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    Celsius or Fahrenheit? Paraffin melts at around 40°Celsius, which is a little over 100°Fahrenheit. Its flash point is 200°Celsius, which is just shy of 400°Fahrenheit. 100°C is the boiling point of water (212°F). I doubt a heated car seat cushion gets that hot. Same thing for a heating pad. They're usually capped at about 80°C (176°F).

    Also, just because a heater gets a certain temperature at the heating mechanism, doesn't mean that it'll be that hot a few feet away from the mechanism. For instance, you can sit a few feet in front of a campfire and be relatively comfortable, even though the fire itself is around 600°C (1100°F).
  9. Jul 1, 2017 #8
    Its Celsius… you are right, I just have to find the right system… thank you very much for your feedback!
  10. Jul 1, 2017 #9


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    These are a thing and they use soy wax which has an even higher melting temperature than paraffin. I would suspect that having melted wax around is not so much a safety issue otherwise these would not be a product. A bigger safety issue is that if you have a very large amount and it spills suddenly you can scald anyone that is nearby. Small splashes should not be a problem.

  11. Jul 3, 2017 #10


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    I would also think about fluorinated waxes as used in skiing.
  12. Jul 3, 2017 #11


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    Halogenated organic compounds are the first idea I got, too, but if there's very high temperatures involved, they can release toxic hydrogen halide gases or even something like phosgene (as in pyrolysis of PVC plastic).

    I also found a chemical company website that advertises some kind of inorganic silicone waxes for cosmetology purposes. If they're fully oxidized Si compounds, they're not likely to be dangerous on heating.
  13. Jul 3, 2017 #12


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    Sure, fluorohydrocarbons will release HF when heated sufficiently. But until this happens, at best some firemen equiped with autarkic respiration system will be alive in that room, not because of toxic fumes, but because it will be hotter thant 200 deg C.
  14. Jul 3, 2017 #13


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    Unlike firemen with breathing apparatus, the artist will be in the room at ambient temperature, hopefully not inside a wax flame. Any flame that self-extinguishes may produce a puff of unhealthy smoke each time the flame retardent is activated.

    I think either baking soda and / or borax should be tested.
    They are safe and available from the Baking or Laundry aisles in most local supermarkets.
  15. Jul 3, 2017 #14


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    Ski wax would probably be fine. The big disadvantage is that it costs ~50x more than regular old paraffin wax.
  16. Jul 6, 2017 #15
    We compounded 70% ATH into polyethylene for fire break panels made by Alcoa for the construction industry (sandwiched between aluminum sheet). It is a very common flame retardant, but must be used at fairly high levels to be effective. It is cost effective and safe.

    Decabromodiphenyloxide is another popular FR in polyethylene. However, you do not want massive decomposition of this retardant, You should see a couple hundred pounds of it go off in an extruder. It explodes out both ends, sending hot molten plastic, massive steel, and bromine gas into the the plant.
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