For example, if I cut open an avocado, and don’t clean the knife immediately, the avocado that got on the knife will dry and become nearly impossible to get off. Same goes for foods like egg yolk, melted cheese, pasta noodles, etc.
In: 8
Because they go from liquid to solid. That’s what almost all glues do. Both starch/sugars and protein have the potential to go from a liquid/dissolved state to a solid state as moisture evaporates. When a substance is liquid, it’ll “grab” many kinds of surfaces by wetting them as well as getting into scratches and crevices. If it is solidified in this state, that grabbing force can be quite strong.
There’s a force called Van de Walls forces. These arise when molecules in two objects are placed *extremely* close to another. Normally, most things in the real world have some degree of surface roughness. This means when they touch, there’s only actually a very small contact area, much smaller than you’d expect, and the Van de Walls forces are negligible.
However with a liquid, the liquid molecules are able to get very close to the solid surface. When the liquid turns solid, many molecules remain extremely close so the Van de Walls forces are quite high and the food sticks.
This is one common mechanism for glue between non-absorbent materials to work. (e.g glass to glass)
For example, if I cut open an avocado, and don’t clean the knife immediately, the avocado that got on the knife will dry and become nearly impossible to get off. Same goes for foods like egg yolk, melted cheese, pasta noodles, etc.
In: 8
Because they go from liquid to solid. That’s what almost all glues do. Both starch/sugars and protein have the potential to go from a liquid/dissolved state to a solid state as moisture evaporates. When a substance is liquid, it’ll “grab” many kinds of surfaces by wetting them as well as getting into scratches and crevices. If it is solidified in this state, that grabbing force can be quite strong.
There’s a force called Van de Walls forces. These arise when molecules in two objects are placed *extremely* close to another. Normally, most things in the real world have some degree of surface roughness. This means when they touch, there’s only actually a very small contact area, much smaller than you’d expect, and the Van de Walls forces are negligible.
However with a liquid, the liquid molecules are able to get very close to the solid surface. When the liquid turns solid, many molecules remain extremely close so the Van de Walls forces are quite high and the food sticks.
This is one common mechanism for glue between non-absorbent materials to work. (e.g glass to glass)
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