Page 18 - Science Focus (Issue 016)

the beeswax ester molecules allow them to pack tightly E120 and CI 75470). This blood red dye is extracted in a
together in a regular manner, thus giving a harder
structure.
In mixtures, a sharp melting point is not observed,
but they tend to gradually soften and melt over a
temperature range. The correct mix of beeswax and
cocoa butter is a complex mixture that would be in a
partially molten state at room temperature, making it
just soft enough and neither rock hard nor a puddle.
Color is another important characteristic of lipsticks.
Back when synthetic dyes were not yet known, people
could only look to nature for the colors they desired. The
major red pigment used back then (and nowadays!)
was carmine (also called cochineal, carminic acid,
Behind the Transformative Power of
Lipsticks
1 酯類(RCOOR')是由羥基(OH)和羧基(COOH)
縮合而成的產物；在縮合作用這個偶合反應
（coupling reaction）中水分子會被釋出。
2 C 30 醇是指碳鏈（又稱碳骨架）中含有30個碳原
子的醇。
3 三酰甘油亦是酯類化合物的一種，但當中醇的部
分是甘油 — 一個在C 3 骨架上有三個羥基的三元
醇（triol）；三個羧酸分子因此可以與其縮合產
生三酯（triester）。
literally bloody process, by grinding the dried female
cochineal insect, Dactylopius coccus, which live as
parasites on cacti [2]. I believe it may scare many of you
that what you are applying onto your lips were made
from crushed insect bodies. Besides, although carmine
is widely used in cosmetics, it has been known to cause
allergic reactions in a very small number of people [3].
Luckily, there are also carmine-free products available
in the market for vegans and people who are allergic
to it.
A more recent pigment used in lipsticks is eosin,
which creates a long-lasting sharp red color only after
application because it reacts with amine groups (NH )
2
present on skin surface proteins [4].
Color-changing lipsticks are recently in fashion and
they rely on color-changing chemistry. Some of them
employ color masking, in which an originally light-
colored dye (such as eosin) would be initially masked
by a darker pigment so the lipsticks do not appear
顏色。當時主要的色素（現在也是！）是胭脂紅（carmine，
亦稱胭脂蟲紅（cochineal）、胭脂紅酸（carminic acid）、
E120 或 CI 75470）。這種血紅色色素的提煉方式確實很
血腥，那是透過磨碎烘乾了的雌性胭脂蟲 Dactylopius
coccus（一種仙人掌上的寄生蟲）來提取的 [2]。你有沒有
因為自己曾塗過由磨碎蟲屍製成的產品而感到一絲心寒
呢？順帶一提，雖然胭脂紅被廣泛使用於化妝品裡，但是
一小部分的人還是會對胭脂紅敏感 [3]。幸好，現在市面上
已經有一些不含胭脂紅的產品供純素食主義者（vegans）
和敏感者使用。
另一種較近期用於唇膏裡的色素是伊紅（又稱曙紅），
它能透過與皮膚表面蛋白質的氨基（NH ）發生化學作用，
2
只在塗抹後變出持久的鮮紅色唇妝 [4]。
最近流行的變色唇膏背後其實也是靠著化學的原理。
有一些唇膏利用顏色掩蓋技術，用更深的色素掩蓋原本淺