Q:

「日焼{ひや}け」 is not representative of a means to nominalize verbs?

I was just thinking about the sunburn I will get during the upcoming 4th of July holiday. Then, I wondered if 「日焼{ひや}け」is a verb nominalization. If it is, I am not aware of such a pattern.
Is it an ad-hoc conglomeration of the idea of "sun", "skin", and "burn"?
「日は人間の肌を焼ける」
「日は焼ける」// make the object implicit
「日焼ける」// drop the article
「日焼け」// drop the trailing "る"
Or, is this representative of a certain verb nominalization process that can be used to nominalize other verbs?

A:

These are (deverbal) noun-noun compounds:

The first noun is either an adjunct to or an argument of the verb.
The second noun is a deverbal form of a verb—specifically, its 連用形 ("continuative form"), a verb form used as a noun.

When the nouns are put together, rendaku ("sequential voicing") sometimes occurs:

If the first noun is an adjunct, rendaku usually applies (96% of the time, if possible).

If the first noun is an argument, rendaku sometimes applies (44% of the time, if possible).

The numbers above are from Kyoko Yamaguchi's paper Accentedness and Rendaku in Japanese Deverbal Compounds (2011), which discusses this topic in more detail.
Some examples from Tsujimura's Introduction to Japanese Linguistics to illustrate the difference:

　絵を描く　→　絵描き（えかき）　　　絵を is an argument
　手で書く　→　手書き（てがき）　　　手で is an adjunct, rendaku occurs
　物を干す　→　物干し（ものほし）　　物を is an argument
　陰で干す　→　陰干し（かげぼし）　　陰で is an adjunct, rendaku occurs
　魚を釣る　→　魚釣り（さかなつり）　魚を is an argument
　磯で釣る　→　磯釣り（いそづり）　　磯で is an adjunct, rendaku occurs

Voicing happens with arguments as well, but less than half of the time:

　人を買う　→　人買い（ひとかい）　　人を is an argument
　人を殺す　→　人殺し（ひとごろし）　人を is an argument, rendaku occurs anyway

Deverbal compounds of this sort are quite common in Japanese.

A:

This is a common pattern of taking a noun + particle + verb combination and shortening the verb to it's stem form:
As Choko points out in her comment to your question:

日に焼ける drops the particle に and changes 焼ける into the stem 焼け => 日焼け
炭火で焼く drops the particle で and changes 焼く into the stem 焼き   =>　炭火焼き
家で飲む drops the particle で and changes 飲む into the stem 飲み     => 家飲み
花を見る drops the particle を and changes 見る into the stem 見       => 花見
道を行く drops the particle を and changes 行く into the stem 行き     => 道行き

There are similar phrases that aren't created exactly in this way, but similarly. For example:

遊び食べ

And others that have more nuanced meanings

裏行き does not just mean 裏で行く but references a distance.

So it's not a fast rule, but holds in many cases.

