Page 16 - Science Focus (Issue 016)

If office ladies are asked to put only one cosmetic The secret behind this “golden ratio” lies in the
product on their faces, many of them will choose to chemistry of these two major substances. Beeswax
1
have lipstick as it drastically increases the redness is largely consisted of saturated esters , such as
of their lips, making them appear more vibrant. To triacontanyl palmitate (Figure 1). In this beeswax
produce a high-quality lipstick, a variety of chemicals ester, both components feature long and saturated
2
are specifically chosen in the formulation to achieve hydrocarbon chains (a C alcohol & a C16 acid).
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the desired texture and color. Cocoa butter, on the other hand, is mostly made up
of triglyceride (fat) molecules. A common triglyceride
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Beeswax and cocoa butter are two of the most in cocoa butter (Figure 2) features palmitic acid (C16,
commonly used ingredients in lipsticks that together saturated); stearic acid (C18, saturated) and oleic acid
make up the bulk of the product. Lipsticks need to be (C18, monounsaturated).
soft enough to slide over our lips but stiff enough to stay
intact during their application. A group of scientists The hardness of these substances at room
investigated the effect of varying the proportions of temperature is linked to their melting points. Melting
these ingredients: they found that hardness depended point is the temperature at which the molecules
upon the amount of beeswax and spreadability have sufficient kinetic energy to break free from the
depended upon that of cocoa butter [1]. Thus, having intermolecular forces holding them together as a solid.
the right ratio of these two ingredients will give the The strength of the intermolecular forces in this case, lies
perfect lipstick. within the molecules’ ability to pack tightly: since the

Behind the Transformative Power

of Lipsticks

綻 放 生 命 色 彩 的唇膏 By Eunice Lam 林杏妍

如果我們要辦公室女士們只選擇使用一種化妝 蜂蠟和可可脂是兩種最常使用到的唇膏材料，亦是構
品，大部分人都會選擇唇膏，因為它能大幅提升嘴唇的紅 成唇膏的主要成分。一枝唇膏要有能輕鬆滑過嘴唇的軟度
潤度，瞬間營造神采飛揚的容顏。要製造高質素的唇膏， 和在塗抹時不會折斷的硬度。一組科學家曾經研究不同比
我們需要特別挑選不同的化學物質，並以特定的比例調配， 例的蜂蠟和可可脂對唇膏硬度的影響：他們發現，蜂蠟的
方可造出理想的質感和顏色。 份量決定唇膏的硬度，而可可脂的分量則決定唇膏是否能
容易地塗上嘴唇 [1]。因此，兩者需要有一個理想的「黃金
比例」才能造出一枝完美的唇膏。