Do Different Shaped Candles take Different Time to Burn?" An easy science experiment you can do at home. (WITH PARENT SUPERVISION ONLY)
Section 1: Introduction
A. I have always enjoyed relaxing in a hot tub with my favorite candles burning, soothing me in their various aroma therapy. As I would lay there watching my candles burn, it never crossed my mind that the shape of the candle may have something to do with how long it burned for. I always ended up blowing the wicks out of the ones I deemed to be the prettiest, as to save them for another day. Today, for this experiment I will be focusing on the time it takes candles of the same weight, mass, and material but different shapes to burn.
After conducting a literature search, I found that there are several factors that determine the length of time at which a candle burns: how big the candle is, the type of wax the candle is made from, the type of fragrance added to the candle, the material that the wick is made from, the length of the wick, the type of container that holds the candle, and a few more variables.
The type of wax also matters significantly when discussing candles burn time. There are many different types of candle wax: paraffin wax, soy wax, bees wax, palm wax, coconut wax and many others just to name a few. Each different type of wax has a completely different rate at which it burns as they are made from different ingredients.
To get the maximize amount of burn time out of your candle the wick should be a quarter of an inch in length. And should be made of a material that is porous so that it can soak up and retain the liquid wax. Cotton is the recommended wick material but not always used. Some candle makers use lead wicks which can be dangerous and harmful to both the user and the environment.
I did not find another experiment done testing the influence of shape on candles burn time, I did however find interesting experiments done on why and how a candle burns.
Section ll: Hypothesis
B. My hypothesis: I predict that the candle shape will not affect the time that it burns.
C. I am basing my hypothesis on research that states, the wick doesn’t burn, it’s the oil from the candle wax that is being drawn into the wick that is burning. So, I believe that although the shapes might be different the masses of each candle will be the same, therefore, they should all burn equally.
Section lll: Methods
D. The independent variable is the shape of the candle. There are 3 standard shapes used by candle makers aside from the variety of decorative modern candles. These shapes are sphere/ball, pillar, and taper.
E. The dependent variable is the time it takes to burn to a determined length down the candle. This will be measured by using a standard clock with hours, minutes, and seconds to determine the amount of time it takes each candle to burn one inch in depth. Each candle will be pre marked in inches using a standard ruler before burning begins. I will record the time in my notebook and transfer the data to digital format. I will provide the data display in my written report as well as in a bar graph format.
F. I will be controlling for the following confounding variables:
l. Wax type: All candles will be made from paraffin wax so that the wax type does not affect the rate at which the candle burns.
ll. Wick material: All wicks will be made from cotton so that the type of wick does not influence the burn rate of the candle.
lll. Wick length: I will trim all wicks to a quarter of an inch in length. This will be measured by my standard ruler. This is to ensure all candles start from the same burn point.
lV. Type of fragrance oil: All candles came from the same candle maker thus reducing the possibility of different types of fragrance oil used so that all candles will have the same opportunity of burn time without extending any advantage due to additional or different oils added in the candle.
V. Atmospheric movement: I will conduct the experiment indoors away from any air conditioning vents, windows, or fans preventing any additional air currents from effecting the burn time of the candles.
Vl. Candle weight: All candles will be equal in weight. I will trim wax off each candle until all of them weigh 7oz. or 198.4 grams. Weight will be measured using a common kitchen scale. This will prevent any of the candles from having an unfair advantage in burn time.
Vll. Candle Mass: All candles will weigh 7oz. or 198.4 grams. Thus, all candles will have equal mass. This will also prevent any of the candles from having an unfair advantage.
Vlll. Type of container: I will be using raw candles with no container to avoid this influencing the burn time.
lX. Length of burn: I will be measuring and marking each candle at one inch in length to make sure each candle burning length is equal. This is so that I can see if only the shape influences the rate at which each candle burns.
G. Materials and Measurements:
I will have 3 candles all made from paraffin wax.
2.25” x 7” Slim Pilar Candle
3” x 6” Pilar Candle
2.8” Sphere/Ball Candle
1 standard clock that has hour, minutes and a second hand. To record the time, it takes each candle to burn to 1 inch.
1 standard ruler showing inches and centimeters, but I will be making my measurements in inches.
1 standard kitchen scale showing weights in grams up to a tenth of a gram.
1 regular kitchen steak knife to trim down wax off the sides of each candle to ensure they all weigh the same.
1 marker to mark the outside of the candle at 1 inch so I know where to stop the burning and end the timer.
1 lighter to light the candles and start the timer.
H. Experimental Procedure:
The first part of the procedure is to gather all 3 of my candles, my kitchen knife, and the scale.
I weigh each candle and shave the wax down slightly on them until they all equal 198.4 grams on my scale.
Then I take my ruler and measure 1 inch down from the bottom of the wick (or the top of the candle) and I draw a line with my marker on each of the candles at 1 inch.
Then I line up my 3 candles, using my ruler I measure 1 foot apart so that they’re not directly next to one another where their flames can affect the next candle.
Then I get my clock and lighter ready. Noting the time, I light each candle at exactly 7pm and start the clock.
I wait until each candle burns down to the marked 1-inch line, blow them out, note the time for each candle and record my findings.
Section lV: Results
I. After burning each of the candles, I found that 2 of the 3 candles, the pilar and the sphere/ball candles burned at the same rate at 19 minutes to get to the 1-inch mark. Whereas the slim pilar candle took only 15.75 minutes to burn to the one-inch mark.
J. The results do not entirely agree with my hypothesis and are displayed below.
Section V: Conclusions
K. These results partially confirmed my hypothesis that the shape of candles will not effect burn time as it did not with 2 out of three candles. The 3rd candle, or candle number 1 the slim pilar, did burn at a faster rate then the other two. I believe after watching the candles burn that I know why this happened. I believe that because the taller slender candle had less wax near the burning point of the flame that the wax evaporated into air at a quicker rate, allowing the candle to melt faster than the candles that were thicker with more of there mass centered around the burning point. But I suppose that would take a whole other experiment to prove.
L. Even though I attempted to control for mass, there was an even advantage for the slim candle with less mass around the wick. This uncontrolled confounding variable most likely impacted my results. If the candles were more similar and yet still different shapes, the results could have been different. Further experiments that better control for mass will have to be done to determine shapes influence on burn time.
