Strong molten mirror

Job 37:18 says

Can you, like him, spread out the skies,/
hard as a cast metal mirror? (ESV)

will you, with him, spread out the clouds,/
solid as a mirror of molten metal? (NET)

can you join him in spreading out the skies,/
hard as a mirror of cast bronze? (NIV)

Can you, with him, spread out [raqa`] the skies [shachaq],/
strong [chazaq] as a mirror [r'iy] of molten [yatsaq] metal?

raqa` means to "spread out".

shachaq is more often translated "clouds" or "dust". It is less often used for "heaven" and the more common word for heaven is the Bible is shamayim.

chazaq means "strong", so "hard" or "solid" seems reasonable if the context is that of a solid object.

r'iy means means "appearance" and it is used here in Job and nowhere else in the Old Testament. The more common word for mirror is mar'ah. Mirror may seem an appropriate translation based on the meaning "appearance".  However the Septuagint doesn’t translate the word as “mirror” but “appearance”.

yatsaq means to "pour out". It is translated into English as "molten" only here. As mirrors were made of metal (not glass) poured out metal is molten metal. Thus a reasonable translation if mirror is also correct. Yet what is a molten mirror? One in the process of being cast (see ESV and NIV)? But a molten mirror would not be hard or strong, though perhaps mighty or powerful.

Going with the more usual meanings of the words (if the context allows it) we get, as per the NET,

will you, with him, spread out the [strong] clouds,/

Newman translates the whole verse,

Can you, with Him, spread out the mighty clouds,/
With an appearance of being poured out?

Or more colloquially,

Can you, with him, spread out the mighty clouds,/
that look like they have been poured out?

---

The Myth of the Solid Heavenly Dome: Another Look at the Hebrew (RĀQÎA‘) by Randall W. Younker and Richard M. Davidson, Andrews University Seminary Studies, No. 1, 125-147. (pdf)

Footnote 62: Job 37:18 records Elihu’s challenge to Job: “Can you, with Him [God], spread out [rāqa‘] the skies [šeḥaqim], strong [ḥāzāq] as a molten [mûṣaq] mirror [re’î]?” Newman, 13-15, examines this passage, and points out, 14-15, that the Hebrew word šeḥaqim normally means “clouds” and not “skies” elsewhere in Scripture. See HALOT, 1464-1465. Unless there is unambiguous evidence in the immediate context that the term should be translated “skies,” it is preferable to translate it as “clouds” here and elsewhere. Several major commentators (e.g., Tur-Sinai, Dhorme, Gordis, and Habel) have seen a reference to “clouds” and not “skies” in this passage (cf. NET which translates the term as “clouds”). Newman, 14, further calls attention to the fact that the word re’î, usually translated “mirror,” is not the normal word for “mirror” in the Hebrew Bible, and, in fact, is a hapax legomenon, translated by the Septuagint as (horasis), which means “appearance” in Hellenistic Greek, not “mirror.” This translation is supported by a slightly different pointing of the same Hebrew consonants (with a composite sheva instead of simple sheva), as (ra’î), which means “appearance” and is found four times in the OT, including a single passage in Job from the same speech of Elihu (Job 33:21). Newman, 15, also notes  that ḥāzāq can mean “mighty” as well as “strong,” and mûṣaq literally means “poured out.” He concludes that since in this verse the context is on-going weather phenomena rather than creation, the following translation of the verse is preferred: “Can you, with Him, spread out the mighty clouds, With an appearance of being poured out?” (ibid.). Regardless of the precise translation of the entire verse, if šeḥaqim means “clouds” and not “sky,” there is no reference to a solid domed sky in this passage. Instead, we have an example of “a non- solid object (clouds) being spread out with use of the verb rāqa‘ ” (ibid.). Alternatively, if one insists on translating šeḥaqim in Job 37:18 as “skies” or “heavens” “like a molten mirror” as in many modern versions, the passage still does not imply a solid metal dome. Kenneth Mathews, who follows this traditional translation, points out that “Job 37:18, which describes skies without rain as a ‘bronze’ expanse (cf. Deut 28:23), is figurative and does not support the common contention that the ‘expanse’ was considered a bronze dome by the Hebrews” (Genesis 1–11:26, New American Commentary 1a [Nashville: Broadman & Holman, 1996], 150).