Glossary of Key Wax Terms
Additive: a substance added to petroleum
products to impart some desirable property, e.g. polymer
may be added to a petroleum wax to increase tackiness,
or food grade butylated hydroxytoluene added to prevent
oxidation in storage.
Alkanes: hydrocarbon having the general
Formula Cnttzn+z, also called a paraffin.
API: American Petroleum Institute
API Gravity: a special gravity scale adopted
by the API for expressing density of petroleum products.
Aromatics: hydrocarbons with an unsaturated
ring structure, e.g. benzene.
ASTM: American Society for Testing Materials,
an organization which sets standards for the testing of
Asphaltenes: one of the principal components
of asphalt, the black or brown solid material
precipitated from asphalt with normal pentane. It is an
arbitrary fraction defined by the method of analysis
Base Oil: a finished petroleum lubricant stock
that when blended with other materials (additives)
produces special purpose products such as engine oils.
Blending: mixing two or more base stock
components to achieve targeted specifications.
"Blending" usually refers to mixing homologous
materials, i.e. two base oils or two petroleum waxes;
"Compounding" refers to mixing base products
Catalytic Dewaxing: a catalytic hydrocracking
process that uses molecular sieve catalysts to
selectively hydrocrack waxes present in a feedstock into
lighter hydrocarbon fractions.
Ceresin: an almost white wax produced by
purification of ozokerite; a native mineral wax used in
the manufacture of candles, shoe polishes, electrical
insulation and floor waxes. Also known as ceresin wax,
cerin, cerosin, purified ozokerite.
Clay: granular or finely divided mineral
materials used for treating petroleum. Clays used in
petroleum processing include fuller's earth, bauxite,
bentonite, and montmorillonite. Most common clay used in
the decolorization of petroleum waxes is bauxite.
Cloud Point: the temperature at which the
first signs of wax precipitation appear in an oil.
Color: the color of most waxes is measured
only while molten, because occluded air and surface
finish can cause the color of solid samples of the same
wax to vary significantly.although some commercial
standards for particular waxes, e.g. carnauba, are based
on the color of the solid wax The two most widely used
color standards for waxes are ASTM D1500, used to
measure dark-brown to off-white color, and ASTM D156,
used to measure off-white to pure white waxes.
Compounding: mixing additives with oils,
particularly lubricating oils, to impart oxidation
resistance, rust resistance, detergency, or other
Crystallization: in dewaxing operations,
formation of a solid phase (wax), prior to separation by
Deoiling: the separation process used to
refine slack wax into finished petroleum waxes. The
predominant process operates by chilling a mixture of
feed and solvent to crystallize the wax, then separating
the wax from the oil and solvent mix by filter or
centrifuge. Solvent deoiling may be conducted as an
integral part of a dewaxing/deoiling plant or operate as
an independent plant. Alternate processes for deoiling
include "sweating" the oil from the wax and
Dewaxing: the separation process used to
refine waxy gas oils into wax-free oil. Solvent dewaxing,
in which a mixture of feed and solvent is chilled to
crystallize the waxy portion for removal by filter or
centrifuge, produces low-pour lube base stocks and slack
wax. The slack wax may be deoiled to reduce oil content
and produce fully-refined wax. Alternate technologies
for dewaxing include wax hydroisomerization, in which
wax molecules are branched in a catalytic reaction and
converted into high VI lubricants, and catalytic
dewaxing, in which wax molecules are destroyed and
become lighter, fuels products.
Differential Scanning Calorimetry (DSC): a
test widely used to characterize waxes, DSC measure the
amount of energy consumed under controlled heating and
cooling rates. Curves of heat flow versus temperature
provide insight into the thermal characteristics of wax,
including crystalline transitions such as
solid-to-solid, solid-to-liquid, and liquid-to-solid.
Common values obtained from the curves include the
initial and ending temperatures for heat flow and heat
of fusion, measured in joules per gram. Also called
Thermographic Analysis (TGA)
Gas Chromatography: another test used to
characterize waxes, most useful for relatively simple
structures of vegetable and insect waxes, GC has limited
utility on petroleum and synthetic waxes. Good
resolution can be had on products with one preponderant
structure, e.g. paraffins with a preponderance of
primary alkanes. Products such as microcrystalline wax,
which contain several different branched isomers for
each carbon number plus some cyclic compounds cannot be
completely resolved, but useful information can still be
Gel Permeation Chromatography: method used to
measure the molecular weight distribution for synthetic
polyethylene waxes. Though it cannot match the
resolution available through GC, GPC can discern
molecular weights and molecular weight distribution for
products too heavy for GC.
Hydrocracking: a catalytic refining process in
which large molecules are broken into smaller molecules,
conducted at high temperatures, high pressure and in the
presence of hydrogen.
Hydrofining: a catalytic refining process,
less severe than hydrocracking, in which impurities such
as sulfur and nitrogen are removed from hydrocarbon
streams by reaction with hydrogen.
Hydrofinishing: a mild hydrofining process
used particularly to replace or supplement clay treating
of lube oils and waxes.
Hydrogenation: chemical reaction with
hydrogen. Most common reactions in a petroleum context
is saturation of double bonds to convert olefins to
paraffins, and aromatics to naphthenes, and the removal
of sulfur, nitrogen and oxygen impurities from
Infrared Spectroscopy (IR): Infrared
absorption curves are used to identify the chemical
functionality of waxes. Petroleum waxes with only
hydrocarbon functionality show slight differences based
on crystallinity, while vegetable and insect waxes
contain hydrocarbons, carboxylic acids, alcohols and
esters. The IR curves are typically used in combination
with other analytical methods such as DSC or GS/GPC to
Melt Point: the temperature at which a
material changes phase from solid to liquid. Petroleum
waxes usually do not melt at sharply defined
temperatures because they are mixtures of hydrocarbons
with different melting points. Paraffin waxes are
relatively simple mixtures and can have narrower melting
ranges than microcrystalline waxes and petrolatums which
are more complex in composition and melting behavior.
Paraffin waxes are usually marketed on the basis of
melting point determined from the plateau in the cooling
curve measured in ASTM D87. Other methods of melt point
determination are available, depending on the
composition of the wax. Drop melting point (ASTM D126)
is used for amorphous waxes, e.g. microcrystallines, but
is not reliable for higher viscosity synthetic wax, for
which ring-and-ball softening point (ASTM D36) should be
used. Open or closed capillary tubes are used to measure
the melting point of many natural waxes. The congealing
point (ASTM D938) is the temperature at which a melted
wax ceases to flow, and is more consistent than melting
points for some waxes.
Microcrystalline Wax: hydrocarbons of
molecular weight higher than 450 and less than 800
Naphthene: a type of hydrocarbon,
characterized by saturated ring structures, e.g.
cyclohexane, naphthalene, etc.
Naphthenic acids: organic acids occurring
naturally in petroleum.
Nuclear Magnetic Resonance Analysis (NMR):
used in the polymer industry to measure properties such
as amount and type of branching, polymerized ethylene
oxide content and hydroxyl content. The same techniques
are applicable to natural waxes, and are used for both
characterization and quality control.
Oil Content: ASTM D721 measures the amount of
residual oil left in petroleum wax after refining. Oil
content is determined as that percentage of wax soluble
in methyl ethyl ketone at -31.7'C. The method is
applicable to waxes containing not more than 15% oil. A
similar method, D3235 Test for Solvent Extractables in
Petroleum Wax uses a 1:1 mixture of methyl ethyl ketone
and toluene and may be used on waxes having levels of
extractables as high as 50%.
Olefins open chain hydrocarbons containing one
or more double bonds, e.g. ethylene, propylene, etc.
Paraffins: open chain, saturated hydrocarbons,
e.g. hexane, isooctane, etc.
Paraffin Wax: hydrocarbons of molecular weight
higher than 350 and lower than 520 which are solid at
Paraffin Wax - Fully Refined: paraffin wax
that has been refined to a residual oil content no more
than 1%, usually lower than 0.5% and generally meeting
FDA food grade standards.
Penetration: the standard test for hardness of
wax is ASTM D1321, which measures the depth in tenths of
a millimeter that a needle of certain configuration
under a given weight penetrates the surface of a wax at
a given temperature. A series of penetrations measured
at different temperatures, rather than a single
temperature is preferred. Penetration of softer waxes
and petrolatums may be measured using a cone rather than
Resins: any of a class of solid or semi-solid
organic products of natural or synthetic origin with no
definite melting point. Generally of higher molecular
weight, most resins are polymers.
Saponification Number: ASTM D1387 reports the
milligrams of potassium hydroxide which react with one
gram of sample under elevated temperatures, and
indicates the amount of free carboxylic acid plus any
ester materials which may be saponified. Both the acid
number and the saponification number are generally
provided to give an indication of the free carboxylic
acid and ester content of vegetable and insect waxes and
synthetic waxes containing carboxylic acids or esters.
Scale Wax: a semi-refined paraffin wax with an
oil content of 1 - 3%
Slack Wax: generic term for the mixture of wax
and oil recovered in a dewaxing process; may contain 2 -
35% oil. Typical dispositions are to further process for
finished wax, to process for fuels or to sell into
certain end-use markets.
Total Acid Number: ASTM D1386 reports the
milligrams of potassium hydroxide necessary to
neutralize one gram of sample, and indicates the amount
of free carboxylic acid present. The test is widely used
for vegetable and insect waxes, and synthetic waxes
containing carboxylic acid groups.
Viscosity: ASTM D88 is used to measure the
time in seconds required for a specified quantity of wax
at a specified temperature to flow by gravity through an
orifice of specified dimensions. Viscosity is expressed
as Saybolt Universal Seconds (SUS) at the temperature of
the test. The SI unit for kinematic viscosity is mm2/s