About Bottle Fill Level, Weight vs Volume Measurements, and Head Space
Culinary Solvent is pure ethanol sold in pints, quarts, gallons (consisting of 4x quart bottles), 5 gallon jugs, and 55 gallon drums. Depending on your bottle size, there will be a small portion at the top that makes the bottle look like it wasn't filled all of the way. Some customers have weighed their bottle of Culinary Solvent in an effort to see how much liquid is contained in the bottle, and the results of weighing in "ounces" can often add to the confusion.
This blog post is intended to clarify how we fill, how much is contained in each bottle, the purpose of the head space in the bottle, and provide more information on why a 32 fluid-ounce bottle weighs less than 32 ounces when placed on a kitchen scale.
Why isn't the bottle filled to the top?
The bottles we source are designed to be "leak proof". In addition to the special design of the cap and threads, "leak proof" bottles are also slightly oversized. Filled to the neck, our quart bottles can technically hold 33.6 total fluid ounces and our pint bottles hold 17.5 fluid ounces. The extra room in the bottle, known as "head space", is part of the bottle's design for safety, and is provided to give the liquid contents room to expand or contract (due to changes in temperature) without compromising bottle integrity throughout transport or storage.
About thermal expansion:
Glass bulb thermometers are a great example of the thermal expansion that is possible with ethanol temperature changes. The red liquid contained in the bulb and stem of the thermometer is ethanol, which replaced the old-fashioned silver mercury thermometers. Even small changes in temperature will affect the overall volume of the liquid which is indicated by the liquid's level moving up or down the stem.
How to confirm your bottle contains the amount stated on the label.
There are two methods you can use to confirm the bottle contents are accurate to the label, 1.) measure by volume or 2.) measure by weight.
How to measure by volume.
This method is the simplest quickest way to measure the contents of your Culinary Solvent bottle. Obtain a measuring cup and pour the contents into the cup. Quarts bottles will contain 32 fluid ounces, pint bottles will contain 16 fluid ounces. After confirming, carefully transfer the contents back into the bottle using a funnel.
How to measure by weight.
Measuring the contents by weight is the most accurate method and can be done without removing the liquid from the bottle. We recommend measuring the bottle using metric units (grams) to alleviate the confusion presented by ounces vs fluid-ounces. All digital scales have the ability to measure in metric (grams) and imperial units (ounces). Please refer to the instructions that came with your scale if you are uncertain on how to change units measured.
How much does 32 fluid-ounces of 200 proof ethanol weigh?
32 fluid ounces (fl.oz.) of 200 proof ethanol weighs 26.34 ounces (oz). Converted to metric, 26.34 ounces (oz) is equal to 746 grams (g). Including the bottle and cap, your quart of Culinary Solvent should weigh about 810 grams (g) total.
How much does 16 fluid-ounces of 200 proof ethanol weigh?
16 fluid ounces of 200 proof ethanol weights 13.17 ounces. Converted to metric units, 13.17 ounces is equal to 373 grams. Including the bottle and cap, your pint of Culinary Solvent should weigh about 405 grams (g) total.
What if they weigh a little more, or a little less?
There is a variance in how much each bottle and cap weighs, sometimes by as much as 4 grams. Also, there is a permittable tolerance in our bottle fill procedure which may also affect the final contents by 1% (1-2 grams). Combined, your bottle may weigh a little more or a little less than the values stated above.
But why does my 32 fluid-ounce bottle weigh less than 32 ounces?
The answer comes down to density of the liquid inside the bottle, coupled with some natural confusion presented when using the word "ounces" to measure both volume and weight. This confusion is eliminated when measuring in metric, where grams denote weight (actually mass), and liters denote volume.
About Density of 200 proof ethanol
Density is the measurement of a material's mass compared to the volume it displaces. The density of water is 1.00 g/ml (grams per milliliter). This measurement for water is equivalent to 0.9587 oz/fl-oz (ounces per fluid ounce). 32 fluid-ounces of water, ignoring the container holding the water, will weigh about 30.7 ounces on a digital scale.
However, the density of 200 proof ethanol is significantly less than water, measuring in at just 0.789 g/ml. Converted to imperial units, the density of ethanol will be 0.823 oz/fl-oz. This difference in density is the reason why a 32 fluid ounce bottle of ethanol weighs less than a 32 fluid ounce bottle of water.
Why can't I convert fluid-ounces directly to grams?
Because fluid ounces is a measurement of volume, and grams is a measurement of weight, it is not possible to convert fluid ounces to grams without first knowing the density of the material being measured.
Using the numbers presented, the contents of one 32 fluid-ounce bottle of ethanol (with a density of 0.823 oz/fl-oz) should weigh approximately 26.34 ounces on a scale. The average weight of an empty bottle and cap comes in at about 2.5 ounces, pushing the total weight of an unopened 32 fluid ounce bottle to about 28.8 ounces.
How are bottles of Culinary Solvent filled at the distillery?
We use a "4-head bottle filler" at the distillery which is a machine that allows us to fill four bottles at one time. Our bottle filler is calibrated each bottling run to ensure an accurate and consistent fill throughout the run, and as required by regulations that govern our industry. In addition to calibration, each bottling run has a "fill test" performed at the beginning, middle, and end of the run to ensure consistency throughout the entire process. The allowable tolerance for our bottle filling system is +/- 1%. For a quart bottle containing 746 grams of ethanol, this tolerance equals 8 ml (milliliters) or 1.5 teaspoons of total liquid.