This part is very
important! Please read carefully! In order for a fragrance
oil to be safe for use in gel, it must be
non-polar, and over 170 flash point.
Non-polar means that the fragrance is miscible (will mix well) in mineral
oil. There is a way to test for this, and I strongly recommend
testing any fragrance you plan to use before using it in gel.
to test for Polarity:
is a simple test that was developed by a lab so that the home user would
have an easy,
and accurate method of testing fragrances.
One: First make sure your glass is clean, dry and clear (easy
to clearly see through). Some glass
can have flaws in it and may not give you a good clear view. We use
scientific grade test tubes, but you
can use small, clear glass oil bottles.
Take 3 parts fragrance oil and mix it with 1 part white mineral oil. (Example:
3/4 tsp. to 1/4 tsp.). Eye
droppers (pipettes) or syringes with measurements on them will work for
this. The correct type of oil to
use is a straight cut mineral oil with a viscosity
of about 230 SUS@100F and a flash point of around
435-440F. The food grade mineral oil
you can get at your local pharmacy will work fine. You cannot use
baby oil, as it already contains fragrance, and will not give you an accurate
We use only Penreco mineral oil in our testing.
Mix the oils thoroughly (put it into a clear glass bottle with cap, and
shake well). If the mixture clouds
for a second as you mix it, but then clears up as you continue, that may
be ok. Let it sit for no more than
5 minutes. If it stays cloudy no matter how much you mix, it is polar
& unsafe. If there is any separation
line or beads, it is polar & unsafe. If it remains clear
and there is no separation, then do the second part
of the test below.
Two: The next step is to reverse the proportions and do the test
using 1 part fragrance and 3 parts
mineral oil. It is important to do it both ways and make sure there
is no clouding or separation in either
mixture. The easiest way to do this is to add 8 parts mineral oil to the
mixture you already have in the
bottle and shake very well. Let it sit for no more than 5 minutes.
If there is any clouding or seperation,
then it is polar & unsafe. If the mixture is completely clear
with no hint of cloudiness, beading or any
seperation line, then it is non-polar, and therefore safe to use.
I find the best way to see really clearly is to hold the bottle up to a
light, this way you can see any
fine lines or beads. Sometimes they can be difficult to see!
are a couple of examples of polarity tests I did in clear glass test tubes.
In this example, the oil on the left clouded up and proved to be polar.
But the oil on the right remained perfectly clear with no separation or
clouding at all and proved to be non-polar.
gel safe Non-Polar:
Why is Polarity so important?
Gel is a non-polar substance, therefore
it will only mix completely with other non-polar substances. It can sometimes
appear to mix with some polar substances, but looks can be deceiving!
Even though it looks as though it's mixing well now, the likelihood of
separation down the road is greatly increased. Due to the wide variety
of ingredients used in fragrance oils, the end result is a wide range of
polarity levels in the finished products. Some oils are more polar
than others, some more non-polar than others. In order for a scent
to mix properly with gel it needs to be as non-polar as possible.
Polar fragrances can cloud the gel, which is a sign of separation.
They can also form pockets, or " pool". Pooling can occur anywhere
throughout the candle, not just on the top where it can be easily detected.
It can sometimes take months for separation and pooling to occur.
If you burn a candle that has "pockets" of fragrance oil that have separated,
once the flame reaches that oil pocket it will likely flare up, causing
possible injury or fire damage! Polar fragrances also lower the overall
flash point of the gel to a greater degree than a non-polar fragrance with
the same flash point.
|Penreco's Stance on Polarity Testing
The following is information
posted by Edward from Penreco in answer to the recent questions about polarity
There has been quite a lot
of talk recently about the polarity test. Who came up with it? Is it accurate?
Why do it? What does it really mean? I will try to keep this short and
simple. The test was developed by our labs with input from fragrance houses
to design a simple test for the polarity of fragrances with mineral oil,
the predominate material in candle gel. Polarity and flash points of the
fragrance oils have been identified as the main cause for candle gel fires.
We have been able to produce candles that flare in our labs and have conducted
reviews of the remains of candles given to us that flared. Polarity and
over scenting were the main culprits. The tests of one part fragrance oil/3
parts mineral oil and 3 parts fragrance oil/one part mineral oil is conservative,
simple and accurate test for polarity. This is what we wanted, to design
something anybody could do. If the fragrance you are testing separates
or creates haziness in either of the two blend ratios, then there is a
chance that there is some polar structure to it. For safety reasons we
wanted a conservative, simple test and that is why it is done with mineral
oil, not gel. Fragrances themselves are complex chemicals and there are
numerous vehicles that are used as carrier oils. A simple test for a complex
chemical needed to be designed and that is what the polarity test is. Obviously
Penreco wants to see this market continue to grow, we have committed capital
and resources to our gel business for 10 years now. We have been producing
and marketing gels for over 9 years. We feel the candle gel market is no
fad, and we plan on supplying candle gels for many more years to come.
Because of this we are committed to the safety of the consumer. A fail
proof polarity test is part of the overall package of safety factors that
we feel needs to be passed on to the industry. There are a number of companies
that have been started to serve and supply this industry, that is great
and we applaud and welcome their efforts. But the safety information that
we pass on has been developed over several years and with help from many.
If you want to see more on the safety and handling of Penreco candle gels
you can visit our web site at www.penreco.com.
What is a flash point?
A flash point is
the temperature at which a substance will flash, or catch fire when a flame
is passed over it. The flash point of a fragrance
is important because adding fragrance to the gel lowers the gel's flash
point. For that matter, adding any substance with a lower flash point
than the gel itself, will lower the finished product's flash point.
You want the end result flash point to stay as high as possible, no less
than 100F degrees above the temperature of the melt pool. The flash
point of Penreco Versagel™
is 440F. The melt pool temperature refers to how hot the melted
gel around the burning candle's wick gets.
melt pool temperatures for the various types of Versagel™
are as follows:
CLP (Low Density)
= 258 F
CMP (Medium Density)
= 275 F
CHP (High Density)
= 281 F
average paraffin wax candle melt pool is around 170F)
You want the overall
flash point of your gel and fragrance mixture to be at least 100F higher
than the gel's melt pool temperature (ie: 375F) to ensure that the melt
pool will not be hot enough to cause the gel to flash (catch fire or flare
up). Let's say you're using 5% non-polar fragrance oil with a 170F
flash point, and 95% gel with a 440F flash point. 5% x 170 = 8.5
and 95% x 440 = 418. When you add the two totals of 418 + 8.5 and
you get a final flash point of 426.5. This means by adding that fragrance
oil, you've lowered the flash point of the gel 13.5 degrees, or a little
This is still a
safe level, but also the lowest recommended. If you were to over
scent the gel and use more than is recommended, it would lower the flash
point even more. Even if you were to use a fragrance with the same
170 flash point, but that was polar instead, because of the chemical nature
of polar oils, it would lower the flash point of the gel even more than
the non-polar one.
How much to
using no more than 3% (1/2 oz per pound) in Low Density gel, and up to
5% (3/4 oz per pound) in Medium or High Density gel. Measure your
fragrance by weight, not liquid volume. I suggest using an accurate
Make very sure to
completely and thoroughly mix your fragrance oil in the gel! This
cannot be stressed enough. Even when using the right kind of non-polar
170+ FP fragrance, it is still imperative that the oil be mixed in well
to avoid any possible separation. Stir stir stir, for at least 2
full minutes! And when you think you've probably stirred enough,
stir as much again just to be safe!
Where to get
I recommend buying
fragrance oils that are specifically formulated for use in gel,
and buying from only reputable sources. If a fragrance company does
not specify their fragrances to be safe for gel, you will need to get MSDS
sheets on them and determine the flash point, and then test them for polarity.
Even if a company simply labels them "gel safe", be sure to question them
on how they determined this, and verify that they have been tested properly.
It is still a good idea to test a small amount from each new batch you
get just to double check, even if it is stated as safe by the supplier.
Manufacturers can make mistakes sometimes too and there can sometimes be
variances in batches, so it's best to be responsible for the testing yourself
and leave no doubts.
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