3 many people don't understand the non-Newtonian fluid part.
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The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid (starch makesmakes liquid more viscous which is why it's part of (usually in the form of flour) basic culinary sauces) when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.

The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid (starch makes liquid more viscous which is why it's part of (usually in the form of flour) basic culinary sauces) when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.

The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid (makes liquid more viscous) when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.

2 many people don't understand the non-Newtonian fluid part.
source | link

The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid (starch makes liquid more viscous which is why it's part of (usually in the form of flour) basic culinary sauces) when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.

The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.

The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid (starch makes liquid more viscous which is why it's part of (usually in the form of flour) basic culinary sauces) when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.

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source | link

The cornstarch does indeed prevent the extremely fine grained sugar from caking, but it also serves a purpose beyond that. Since cornstarch forms a non-Newtonian fluid when water is added, adding it to powdered sugar allows you to use it to make glazes and icings. Without the cornstarch, you'd just be pouring sweet water over your pastries, but with cornstarch you have a glaze that will coat and set.