molding-urethane.md

 Urethane cast photoelastic samples
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-Here is a test equation: \( \alpha = \sum_i \beta_i \)
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 Photoelastic samples can be cast! And this is, by far, the most convenient way to get it: more versatile (shape, mechanical properties, color...), cheaper, and without absolutely any residual stresses. Different photoelastic materials are castable. In this section, we will talk about urethane but you can also look [here](/molding-gel) to see how to make photoelastic samples from gels. Acrylics are another popular photoelastic material.
 
 This method is based on products you can find online at [Smooth On](https://www.smooth-on.com/). We emphasize here that the different authors of this wiki do not have any link of any sort with this company unless it is clearly specified in a paragraph.