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pughaus

Estimating Melt Point in Wax Blends

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This one's for the math + chemistry inclined...

 

If you're making your own blend of waxes, as so many of us do- How would you go about estimating the melt point (MP) of your finished product?

Here's what I've come up with:


Lets use a 3 wax blend as an example:

 

Wax 1 MP appx 125 at 70%
Wax 2  MP appx 140 at 20%
Wax 3 MP appx 95 at 10%

 

125 x .70 = 87.5

140 x .20 = 28
95 x .10 - 9.5
Total  125 MP

Am I doing this right?  Is it even possible to estimate  a final MP like this or do wax compounds interact in a way that changes MPs such that you can't really even ballpark  it with basic math.

 

Edited by pughaus

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Your math is impeccable, but maybe not your chemistry. A things melting point doesn’t change just because you mix it with similar things. So the temperature where everything is melted is the highest melt point of the components. In your example your melt point should be 140°, at anything less than that wax 2 will simple be a solid in suspension. But wait you say; when you mix salt and water it changes the melting point of the ice. That is true, but the salt is dissolved in the water, and it never melts. Your waxes are mixed, so they should keep their own melt points. Of course I could be wrong; it has been 35 years since I studied chemistry.

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@forrest

If I understand correctly, you're saying a blend of 2 waxes will become a wax with the same MP of the ingredient in that blend that has the highest MP? Is that right?
 

So if I melt down: 90% coconut (MP of 72) + 10% paraffin (MP of 140) to create a wax, that final wax now has a MP of 140?  :confused2:

Edited by pughaus

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That is what I am saying; however it could be affected by the various additives they add to the waxes., but the safe bet is go with the highest melt point.

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Well, this is quite a revelation to me!  A little googling and I found almost my exact question answered  by a Prof of Chemistry on another forum:

Andrew Wolff, Adjunct Professor of Chemistry
 
The problem with melting points is that while for pure substances the melting point is a single temperature, as soon as you start adding ingredients the melting point becomes a melting range.  Say you had a wax that melted at 40 Celsius.  Add a wax that melts at 60 celsius, and you will not get a wax that melts at 50 Celsius.  You will get a wax that starts to melt at 40 Celsius but is not completely melted until 60 Celsius.  
 
I'm not quite sure how to practically apply this new info. to candlemaking and a finished candle's behavior in heat though.  Or maybe I just don't want to believe ;) Because now it seems that I'm at the mercy of the ingredient with the lowest MP in any blend.  So a candle made with a blend of waxes that range in melt points from 90 - 140 degrees could still start to melt at 90 degrees (eeek) but may not fully melt until 140.  
 
Perhaps I'm overthinking this - it seems the more I read, the more questions I have.  Time to put some of my wax samples in a warm oven and see what happens!

 
 
 
 

 

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4 hours ago, pughaus said:

Is it even possible to estimate  a final MP like this or do wax compounds interact in a way that changes MPs such that you can't really even ballpark  it with basic math.

Bolded  is my experience. Now what is in a given wax product to get it to a specific melt point it’s a shot in the dark coupled with loads of experimentation. 

 

It’s more than just melt point. Manufacturers use drop point and needle penetration to lab test their products. compounds within the blend melt at different temperatures and rates. There’s a range of “acceptable” since not every batch of raw material will be the same. 

 

Waxes like palm have basically two different states: solid and liquid.  There’s no slush in between like soy and some paraffins. I’ve witnessed different wax fractions not even melting in some blends,  crystallizing out in the melt pool. Beeswax goes from solid to salve to thick liquid before giving up to burning. Even at low percentages it changes how other waxes melt and burns. 

 

Unintended consequences of irregular crystal formation can cause things like cavities, cracks, etc. when blending. Then complicate things a bit more pH and with fragrance oils of unknown compounds and it’s even more challenging. 

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2 hours ago, pughaus said:

So a candle made with a blend of waxes that range in melt points from 90 - 140 degrees could still start to melt at 90 degrees (eeek) but may not fully melt until 140.  

Exactly

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