Do there exist materials whose Opacity varies with temperature? E.g a Material that becomes more Opaque as it gets hotter?

  • 1
    $\begingroup$ Are you looking for a reversible effect? $\endgroup$
    – Ed V
    Nov 22, 2023 at 13:09
  • $\begingroup$ Are you asking for solid materials or gases/liquids? Certainly in liquids and gases there are all sorts of nonlinear, complex opacity behaviour that would fit your bill... Solids are just.. not opaque? $\endgroup$ Nov 22, 2023 at 15:49
  • $\begingroup$ Solids. A normally transparent Solid. $\endgroup$ Nov 22, 2023 at 15:57

2 Answers 2


There are certainly materials which change colour with temperature. This behaviour is called thermochromism.


a Material that becomes more Opaque as it gets hotter?

Many meats and other proteins exhibit this property

Salmon: from “ explore.typhur.com/how-to-tell-if-salmon-is-cooked”

Other fish: from “www.beyondsalmon.com/2005/10/is-it-done.html?m=1”

Chicken: from “www.today.com/food/woody-chicken-breast-t258881”

But perhaps the best example is egg whites: from “phys.org/news/2021-03-egg-x-ray-peek-cook.html”

Now, I think I will go eat.


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