Estimating Wax Fill

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Without actually pouring wax into a container, how do you know how much wax it will hold? In short, this is how to do it (with details after the summary):

  1. Find out how much water (weight in ounces) the jar will contain when filled to the desired wax fill line.
  2. Find the specific gravity (or density) of your wax from the MSDS.
  3. Multiply the water weight by the specific gravity to get the wax weight.

Step 1: Find the water weight

First thing we need to do is figure out how much water weight will fill the vessel to the fill line. You can weigh your vessel empty, and then weigh it filled; the difference will be water weight. OR, if you have a scale with a tare function, place your vessel on the scale, tare to zero, and then pour water in until it reaches the wax fill level you would like.

The water weight to the fill line in the Shadowfire single-wick is 12.85 oz.

Step 2: Find the specific gravity of the wax

A reputable wax supplier will provide the MSDS for the waxes they sell. I use Ecosoya Q210 and I purchased my wax from Candlescience. On Candlescience’s website, I download the MSDS for my wax here.

Here’s the MSDS PDF on Candlescience’s product page.

In the MSDS, I look for mention of specific gravity or density… and yup, as I expected, here it is:

Candlescience’s MSDS for Ecosoya Q210 clearly lists the specific gravity in the physical and chemical properties section.

So now I know my specific gravity! I choose 0.89, the smaller number, because it’s always better to have too much wax than too little.

Step 3: Math!

In step 1, I found that my water weight is 12.85 oz. In step 2, I found that my specific gravity is 0.89. The math is super easy:

12.85 oz x 0.89 = 11.43 oz

I round that up to 11.5oz, and voilà: My wax (and FO) fill weight for the Shadowfire single wick vessel is 11.5 oz!

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