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吶喊為挪威畫家愛德華·孟克的作品，其呼喊的「怪異」樣貌形象非常鮮明。857Please respect copyright.ＰＥＮＡＮＡGoAg5BQk5P
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他本人在1893至1916年畫出多個版本，而其中一幅展示在孟克美術館（Munch Museum)的版本因多處黃色地方出現變白及脫落跡象關係（圖1的數字標記區域），自2006年起已甚少公開示人。857Please respect copyright.ＰＥＮＡＮＡJGPyConDeL
857Please respect copyright.ＰＥＮＡＮＡdBnWbJtJan
作品現時正處於光線陰淡、攝氏18度、相對濕度約50%的環境備受保護。857Please respect copyright.ＰＥＮＡＮＡPJHP9jcCJK
857Please respect copyright.ＰＥＮＡＮＡWEoPsG4qgI
857Please respect copyright.ＰＥＮＡＮＡsOUR0j5nir
（圖2）為了解箇中顏料變色及脫落的機制，有科學家對吶喊作品作出深入研究，並在近日發表文章講述得出的結果（Ref1)。857Please respect copyright.ＰＥＮＡＮＡnCfG0IpPGW
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857Please respect copyright.ＰＥＮＡＮＡ9PpmhhUhtl
Cadmium sulfide，為該時期常用作為黃色顏料的化學物。857Please respect copyright.ＰＥＮＡＮＡJ7nStkpidl
857Please respect copyright.ＰＥＮＡＮＡLC4vuLJhd1
同期的文森·梵谷 (Vincent van Gogh)、詹姆斯・恩索 (James Ensor)和亨利·馬諦斯(Henri Matisse)均有利用這種化學物所製成的顏料，而相關的作品亦有出現黃色顏料變白的現象。857Please respect copyright.ＰＥＮＡＮＡQnKrUg34sm
857Please respect copyright.ＰＥＮＡＮＡes5u05uFfV
該時期主要有兩種方式製作Cadmium sulfide，分別為Dry及Wet Method。857Please respect copyright.ＰＥＮＡＮＡQLWnkQynly
857Please respect copyright.ＰＥＮＡＮＡTt6mliBHXR
Dry Method為以300°C至600°C及零氧氣的方式，加上大量硫元素(Sulphur)調配Cadmium sulfide的方式，得出的成品相對上較為純正。857Please respect copyright.ＰＥＮＡＮＡIZHp8qM9hr
857Please respect copyright.ＰＥＮＡＮＡ8pQXNmo5me
Wet Method為將不同的化學物混合在一起（如圖中所示），再以沉澱的方式獲取固體Cadmium sulfide。857Please respect copyright.ＰＥＮＡＮＡ9BDZww6VKD
基於當時技術相對上不太先進，最終的產品會含有較多雜質及副產品。857Please respect copyright.ＰＥＮＡＮＡ643ZmvRWsQ
857Please respect copyright.ＰＥＮＡＮＡik7fgNkvUc
（圖3）科學家在文中嘗試挖取微量的吶喊畫碎粒，再利用各種技術檢測畫中的化學物成份。857Please respect copyright.ＰＥＮＡＮＡdwmQedJ0T5
857Please respect copyright.ＰＥＮＡＮＡWjo0Bu7pjQ
857Please respect copyright.ＰＥＮＡＮＡiVdQdmUGwy
圖3中間的圖片，其紅點代表黃色顏料Cadmium sulfide的存在。857Please respect copyright.ＰＥＮＡＮＡBH6mHDFQI8
857Please respect copyright.ＰＥＮＡＮＡdXgQWCfUMe
下方的圖片，其三種顏色的出現分別代表Wet Method的副產物。857Please respect copyright.ＰＥＮＡＮＡMbZK7YKlZb
857Please respect copyright.ＰＥＮＡＮＡlWVIrmHpxQ
紅點:Cd(OH)Cl857Please respect copyright.ＰＥＮＡＮＡNF2C2JmwWz
綠點:CdSO4857Please respect copyright.ＰＥＮＡＮＡKfT4ajOZQO
藍點:CdCO3857Please respect copyright.ＰＥＮＡＮＡfchow28Hc5
857Please respect copyright.ＰＥＮＡＮＡUfj8xctmpY
這三種副產物，在長久而來的知識中已被確認是顏料變色及脫落的兇手，與吶喊作品所出現的現象不謀而合。857Please respect copyright.ＰＥＮＡＮＡe2QEh1NgX5
857Please respect copyright.ＰＥＮＡＮＡ44T2EH6OdV
（圖4）為進一步了解顏料變色的現象，他們找來了吶喊畫同期帶有黃色顏料的作品(他們已7914數字命名樣本)。857Please respect copyright.ＰＥＮＡＮＡRVNGIr0eYr
857Please respect copyright.ＰＥＮＡＮＡ9V76WGgyQe
857Please respect copyright.ＰＥＮＡＮＡWUAD2HrGKy
拿取畫中碎片後，（圖4左方）他們同樣發現裡頭含有Wet Method的副產物（綠點）。857Please respect copyright.ＰＥＮＡＮＡlhlr54622E
857Please respect copyright.ＰＥＮＡＮＡMZVYf1Bhqg
為了解環境因素對於顏料變色的影響，他們對另一塊畫碎用上90 日相對濕度≥ 95%，攝氏為40°C，無光環境來模仿歲月的摧殘。857Please respect copyright.ＰＥＮＡＮＡ6mQ1ke1WXG
857Please respect copyright.ＰＥＮＡＮＡYw6rtOLEe8
他們發現得到Wet Method的副產物Cd(OH)Cl（綠點）數量大增且集中在一起，其目測得到黃色顏料變白的現象發生。857Please respect copyright.ＰＥＮＡＮＡ7gduyr7dDF
857Please respect copyright.ＰＥＮＡＮＡth4gItRHzJ
然而，用上用上90 日相對濕度=45%，攝氏為30°C，300W光源直接照射的環境來模仿歲月摧殘的話，則沒有感測得到Wet Method副產物的產生和顏料變色現象發生。857Please respect copyright.ＰＥＮＡＮＡUFrE2U2x0H
857Please respect copyright.ＰＥＮＡＮＡAXHySCW26A
857Please respect copyright.ＰＥＮＡＮＡPICe4Jyd6d
（圖5）另外，他們亦對愛德華·孟克那時期捐贈予館舍的顏料油作出檢測。857Please respect copyright.ＰＥＮＡＮＡOQrvGBb3Vi
857Please respect copyright.ＰＥＮＡＮＡT4UGT8VGw9
857Please respect copyright.ＰＥＮＡＮＡKcKr0s4Lif
在畫紙塗上顏料油後，已能測量得到有一定程度份量的Wet Method副產物Cd(OH)Cl（左圖綠點）。857Please respect copyright.ＰＥＮＡＮＡXQLgNFuKP8
857Please respect copyright.ＰＥＮＡＮＡxNXiL4FTtP
（右圖）用上90 日相對濕度≥ 95%，攝氏為40°C的方式摧殘後，綠點數量大增且集中在一起。857Please respect copyright.ＰＥＮＡＮＡf96VNOzbxM
857Please respect copyright.ＰＥＮＡＮＡADcLf1j94x
857Please respect copyright.ＰＥＮＡＮＡqhfwHBFaZ0
（圖6）換句話說，當時期以Wet Method製作的Cadmium sulfide顏料以及愛德華·孟克所使用的顏料油，乃是導致畫中黃色地方出現變白及有脫落跡象的元兇，而其變色的機制主要由相對濕度和溫度而非光線控制。857Please respect copyright.ＰＥＮＡＮＡuHYkDo8P6i
857Please respect copyright.ＰＥＮＡＮＡ7v4VgnqZc0
857Please respect copyright.ＰＥＮＡＮＡuUTB9E8tua
基於這發現，在相對濕度及溫度嚴密的控制下，吶喊他日將來也許會有機會可以再度長期公開示人。857Please respect copyright.ＰＥＮＡＮＡ9Bmavc65bv
857Please respect copyright.ＰＥＮＡＮＡK1jPXbADBz
如果想我快啲出文的話，請入去Penana網站科普專欄–薯不揀單俾一個like以及Bookmark，這對我非常之重要。857Please respect copyright.ＰＥＮＡＮＡwy72cpjxIw
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Link: https://www.penana.com/story/66244/%E7%A7%91%E6%99%AE%E5%B0%88%E6%AC%84-%E8%96%AF%E4%B8%8D%E6%8F%80%E5%96%AE/toc857Please respect copyright.ＰＥＮＡＮＡthdZIgplxx
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同時亦可以在Penana網站裡按「買一嚿/半嚿薯仔」，以課金的方式推動我繼續搜羅資料寫文，多謝。857Please respect copyright.ＰＥＮＡＮＡLq7zLSHh9V
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Link:857Please respect copyright.ＰＥＮＡＮＡzm8JWvGDUt
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio857Please respect copyright.ＰＥＮＡＮＡ28GJ7Ddm7k
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有興趣接收科學資訊的話，歡迎follow IG: potatopigtongue。857Please respect copyright.ＰＥＮＡＮＡtiH9xMn74j
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Ref1:https://advances.sciencemag.org/content/6/20/eaay3514857Please respect copyright.ＰＥＮＡＮＡWqhrIiXKz6
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