molding-urethane.md

@@ -3,7 +3,7 @@ Urethane casted photoelastic samples
 
 Photoelastic samples can be casted! 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.
 
-This method is based on product you can find online at [Smooth On](https://www.smooth-on.com/). We specify 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 paragraphs.
+This method is based on product 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.
 
 The method described in details here have been first introduced by [Cox *et al.*](http://iopscience.iop.org/article/10.1209/0295-5075/115/64003/meta) and [Barés *et al.*](https://www.epj-conferences.org/articles/epjconf/abs/2017/09/epjconf162463/epjconf162463.html). In case you would like to refer to the method in a publication, please cite these papers.
 
@@ -14,7 +14,7 @@ Making a backing mold for the mold of the sample
 
 The backing mold is nothing but the positive of your sample. You need it to cast the silicone mold that you will use to cast the urethane. Unfortunately, the urethane strongly sticks to almost everything (but the silicone we will use) so you definitely need this silicone mold. This means you need its backing mold. You cannot directly machine the urethane mold.
 
-You have different way to make this backing mold. The simplest is to glue something that have the same shape as your final sample in the bottom of a cup. But just like in the examples below, you can also 3D print it of machine it. Here the material you will use does not really matter since the silicone we will cast does not sticks at all.
+You have different way to make this backing mold. The simplest is to glue something that have the same shape as your final sample in the bottom of a cup. But just like in the examples below, you can also 3D print or machine it. Here the material you will use does not really matter since the silicone we will cast does not sticks at all.
 *  3D printed small cylinders backing mold:
 ![2CounterMold_3](/uploads/d4fce3c40acea6200d16d8af68e0bebe/2CounterMold_3.JPG)
 
@@ -34,6 +34,7 @@ Everything you need at this step is:
 *  your baking mold.
 *  protection gloves.
 *  a scale. You can also use anything to measure volumes.
+
 You can find all the safety and processing recommendations for Mold Star 15 Slow [here](https://www.smooth-on.com/tb/files/MOLD_STAR_15_16_30_TB.pdf). Remember to check this first. 
 
 ![3YouNeedMold](/uploads/cc65fb7a22cfeff3e97f543e931e0a2f/3YouNeedMold.JPG)
@@ -51,14 +52,14 @@ And you strongly mix it with the fork taking care of scratching the edges of the
 ![6MakeSilicon_3](/uploads/46102cc9ea65072b7ff5f973dd9e4bcf/6MakeSilicon_3.JPG)
 ![7MakeSilicon_4](/uploads/9d57d6df2661b7d8ac2b21f5f61a0f99/7MakeSilicon_4.JPG)
 
-The silicone is ready you do not need to degas it. Then you slowly pour it in the backing mold, making sure that every edge of the mold is reach. You do not need to take care about bubble they will go away. You can also pour it in access without cleaning, it is easier to clean once cured:
+The silicone is ready you do not need to degas it. Then, you slowly pour it in the backing mold, making sure that every edge of the mold is reached. You do not need to take care about bubble they will go away naturally before curing. You can also pour it in access without cleaning, it is easier to clean once cured:
 
 ![8MoldingMold_1](/uploads/cbb6dafe34304571080e50465db48ff0/8MoldingMold_1.JPG)
 ![9MoldingMold_2](/uploads/68f464c24c7dd797775622a408dbb46e/9MoldingMold_2.JPG)
 ![10MoldingMold_3](/uploads/16fffa459abc62e5fec990c41b4335ab/10MoldingMold_3.JPG)
 ![11MoldingMold_4](/uploads/bcba91fd603b2145b94fa721001a877c/11MoldingMold_4.JPG)
 
-After about 5 hours (over night if you want to be sure):
+After about 5 hours (over night if you want to be sure) the silicone is cured:
 
 ![12IMG_7635](/uploads/2487f1bfa33738b3e2de310f444ab6ea/12IMG_7635.JPG)
 
@@ -78,11 +79,11 @@ Once casted, this mold can be reused a lot of times (~100) until it gets a bit s
 Picking the right urethane
 --------------------------
 
-Before casting urethane, you need first to choose the best for what you want to do. The photoelastic signal is a function of the strain, the larger the more you will have fringes. But if fringes are too dense they will overlap and you will not be able to measure anything. This will happen if you load your sample too much or if it is too soft. On another hand if the sample is too stiff or if you do not load it enough the photoelastic signal will be too weak to see something or to measure accurately. Note that this also depends on the thickness of you sample. That is why, depending on your sample's shape and on how you load it you need to pick the right urethane stiffness.  
+Before casting urethane, you need first to choose the best for what you want to do. The photoelastic signal is a function of the strain: the larger the deformation, the more you will have fringes. But if fringes are too dense they will overlap and you will not be able to measure anything. This will happen if you load your sample too much or if it is too soft. On another hand if the sample is too stiff or if you do not load it enough the photoelastic signal will be too weak to see something or to measure accurately. Note that this also depends on the thickness of you sample. That is why, depending on your sample's shape and on how you load it, you need to pick the right urethane stiffness.  
 
-The castable urethane we use here is the [Clear Flex](https://www.smooth-on.com/product-line/clear-flex/): 'a water white clear urethane liquid rubber compounds designed for applications that require absolute clarity'. It is available in three different shore stiffness: 30, 50, 95. The one we use here is the [Clear Flex 50](https://www.smooth-on.com/products/clear-flex-50/). It is the most commonly used for centimetric samples that will undergo few Newton loadings. Also, not that playing (non linearly) on the quatity of cross-linker (part A) you add in the urethane, you can tune the material stiffness. But be careful because you also play on the curing time!  
+The castable urethane we use here is a [Clear Flex](https://www.smooth-on.com/product-line/clear-flex/): 'a water white clear urethane liquid rubber compound designed for applications that require absolute clarity'. It is available in three different shore stiffness: 30, 50, 95. The one we use here is the [Clear Flex 50](https://www.smooth-on.com/products/clear-flex-50/). It is the most commonly used for centimetric samples that undergoes few Newton loadings. Also, note that playing (non linearly) on the quantity of cross-linker (part A) you add in the urethane, you can tune the material stiffness. But be careful because you also play on the curing time!  
 
-If you want to slightly color the sample for imaging purpose you should use [So Strong](https://www.smooth-on.com/products/so-strong/) dye. In the following we color our sample in green because it is usually the optimum color for polarisers. 
+If you want to slightly color the sample for imaging purpose, you should use [So Strong](https://www.smooth-on.com/products/so-strong/) dye. In the following we color our sample in green because it is usually the optimum color for polarisers. 
 
 
 Casting method