. 1. Appearance and Color:
Pure turpentine should be colorless and transparent. If water is
not cleared in the producing process or the packing vessel is rust,
it turned yellow and turbid. Hence, before production completes,
water should be removed as clearly as possible.
Weight: Specific weight depends on the different kind of terpene
hydrocarbon it contains. Bicycloterpene hydrocarbon has the largest
specific weight, and then Monocyclo-terpene; Open chain hydrocarbon
has the least specific weight.
index: Refraction Index is an indicator of substance property. It
is the ratio of light velocity in two media. With the same acid
value, the higher the refraction index, the more content of
high-boiling pointed distillations in the turpentine.
4. Volume of Distillate
below 170 : This is a major indicator of turpentine quality. Since
-pinene has a boiling point of 155-156 , -pinene 162-163 , and
170-185 for most bicycloterpenes, 254-256 for longifolene, the more
the volume of distillation below 170 , the higher percentage of
valuable contents such as -pinene and -pinene.
5 . Acid Value:
Turpentine is a neural mixture of terpene. In the producing of it,
if rosin foam is taken into the condenser, or if rosin is boiled
off under a high temperature, the output turpentine will be weakly
acidic. High acid valued turpentine can erode the tin containing
it, thus making itself look yellow. Such turpentine need another
distillation before using. Therefore, the acid value of turpentine
should be as low as possible.
Rotation: When a linearly polarized light beam passes through a
liquid containing asymmetric carbon atoms or optically active
substances, an optical rotation will occur, namely, the
polarization plane of the light will rotate right or left. Such
rotations has certain degrees of rotation, this is called degree of
optical rotation. Even the same kind of terpene from different
places has different property of optical rotation. For instance,
the -pinene in the turpentine of China, Portugal and France has a
sinistral optical rotation, while that of Soviet Russia, Greece and
India is dextral. Different species of trees produce
turpentine with different optical rotation. That of mason and slash
pine is sinistral, and that of longleaf pine is dextral.
7. Distillation Residue:
These are mostly resin acid and other neural substances with high
boiling point in the turpentine. Residue content should be as low