|MadSci Network: Physics|
I strongly suspect that the phenomena you observe with Saran wrap adhesion are due to surface roughness.
On the microscopic level, glass and metal will be much smoother than wood – thus, the surface of the Saran wrap will be able to contact the surface of the glass or plastic, but be unable to contact much of the surface of the wood. Although the bonds between wood and Saran wrap are likely to be as strong as the bonds between Saran wrap and glass, the force you need to exert to pull them apart will be much less just because there are so many fewer of these bonds.
On the other hand, if you can actually get the Saran wrap into contact with the wood surface, it will adhere much better than it will to glass or metal due to the larger surface area it can stick to. For example, if you were to melt it onto wood it would be much more difficult to remove than if you melted it onto a glass surface.
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