Page 19 - Science Focus (Issue 016)

red at first. Some may use humidity to trigger a color
change too: for example a colorless dye, Red 27, turns
pink after reacting with moisture on the lips. Another
popular variation, known as “mood lipstick”, uses pH- 1 An ester (RCOOR’) is a condensation
sensitive dyes. As the pH of the lips could vary due to product (meaning that H O is lost during
2
different physiological conditions (e.g. stress, hormonal the coupling reaction) between an alcohol
fluctuation), a “personalized” red color would appear (OH) functional group and a carboxylic acid
(COOH) functional group.
on the lips [4]. 2 C 30 alcohol refers to the alcohol that has
a carbon chain (or known as carbon
Apart from organic colorants, inorganic compounds backbone) with 30 carbon atoms.
are also used. Iron (III) oxide (Fe O ) is often added to 3 A triglyceride molecule is also an ester, but
3
2
lipsticks – the hydrated form of which (Fe O ·xH O) is rust here the alcohol component is glycerol, a
2
2
3
as we commonly know it. Commercial colorants’ shade triol with three OH groups on a C 3 skeleton;
thus three carboxylic acid components will
can be tuned by controlling synthesis procedures, condense with it form a triester.
giving for example, iron oxides with a wide range of
colors. The use of iron oxide colorants is a much safer
and environmentally-friendlier choice than many
organic dyes.
Understanding what is inside a lipstick is very
important as a smart consumer. Next time when you
buy a new lipstick, remember to check the labels first!

綻 放 生 命 色 彩的 唇膏

色的色素（例如伊紅），因此塗上嘴唇前的顏色未必是紅
色。又有些唇膏以濕度引發變色：比如透明色素「紅色 27
號」在與嘴唇上的水份產生作用後會變成粉紅色。還有一
種熱賣的「變種」—「心情唇膏」用上了對酸鹼度敏感的 References 參考資料：
[1] Kasparaviciene, G., Savickas, A., Kalveniene, Z., Velziene, S.,
色素：由於嘴唇的酸鹼值會因應用家不同生理狀況（包括 Kubiliene, L., & Bernatoniene, J. (2016). Evaluation of Beeswax
Influence on Physical Properties of Lipstick Using Instrumental
壓力、荷爾蒙分泌起伏等）而改變，「心情唇膏」可以變出 and Sensory Methods. Evidence-Based Complementary and
個人化的唇色 [4]。 Alternative Medicine, 2016. doi:10.1155/2016/3816460
[2] Pöhnl, H. (2016). Applications of Different Curing Approaches
and Natural Colorants in Meat Products. In Carle, R., &
除了有機調色劑外，也有機會用到無機調色劑。經常 Schweiggert, R. M. (Eds). Handbook on Natural Pigments in
被使用在唇膏上的有氧化鐵（III）（Fe O ），相信大家都 Food and Beverages - Industrial Applications for Improving Food
3
2
Color (pp. 209-225). Elsevier.
很熟識它的水合式（Fe O ·xH O），那正正是常見的鏽。 [3] Arslan, Z. K., & Aycan. Ş. (2014). An Example of the Use of
3
2
2
商業用調色劑的色調可以透過控制合成的步驟來改變，製 Spectrophotometric Method: Determining the Carmine in
Various Food Products. Procedia - Social and Behavioral
造出來的例如有不同顏色的氧化鐵。以氧化鐵作為調色劑 Sciences, 116, 4622-4625. doi: 10.1016/j.sbspro.2014.01.996
[4] Toedt, J., Koza, D., & Cleef-Toedt, K. V. (2005). Chemical
是比用有機調色劑更安全和環保的選擇。 Composition of Everyday Products. Westport, CT: Greenwood
Press. Retrieved June 12, 2019, from https://books.google.
作為精明的消費者，了解唇膏當中的成分是十分重要 com.hk/books?id=UnjD4aBm9ZcC&lpg=PA44&dq=lipsti
ck eosine&hl=zh-TW&pg=PA43#v=snippet&q=beeswax
的。下次購買新唇膏前，記著要先查閱它的成分啊！ lipstick&f=false

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