I was a little surprised to find that the TNIV and NIV 2011 have reverted to the Masoretic text (partially) of Proverbs 26:23 against the 1984 NIV which followed the critical rephrasing of this verse in light of Ugaritic and Hittite evidence (though it includes “silver dross” in the footnote). The updated NIV texts created a mixed text that attempts to blend the emended text of the Hebrew as well as maintaining the traditional (misunderstanding) of the Masoretes (adding “like” and maintaining “silver dross”).
“Like a coating of silver dross on earthenware are fervent lips with an evil heart.” (NIV2011 – emphasis added)
“Like a coating of glaze over earthenware are fervent lips with an evil heart.” (NET – emphasis added)
The issue pertains to the Hebrew כֶּ֣סֶף סִ֭יגִים which is properly translated “silver dross”. Based upon the cognate Ugaritic word spsg “glaze” (and another cognate in Hittite zapzaga[y]a) a significant and clarifying emendation was made by numerous translations. The emendation involves several elements: the admission that vowel pointing and spaces between words were lacking in the original text of the Old Testament. Removing the vowel-pointing (as well as the matres lectionis yods) and spacing of the Masoretes was inaccurate and should be altered to read כסףסגם “like glaze”. The kaph has then been understood to be the comparative preposition “like”, the yods have been dropped as matres lectionis along with the vowel pointing and the mem regarded as an enclitic (ESV, NAB, NIV1984, NRSV, NLT and, of course, the NET have followed this emended reading).
While the LXX retains the Masoretic reading of “silver”, but it offers an expansion (apparently because the translator was equally confused by the sense of the Hebrew): ἀργύριον διδόμενον μετὰ δόλου ὥσπερ ὄστρακον ἡγητέον χείλη λεῖα καρδίαν καλύπτει λυπηράν, “Silver given deceitfully is considered as earthenware, a smooth tongue hides a troubled heart” (my translation).
Part of the reason for opting to prefer the emended text in light of the cognate terms of Ugaritic and Hittite is based upon the notion that “silver dross” would simply not be used for such a thing. Glaze would be applied to vessels (though obviously it should not be applied to earthenware unless it is being used to conceal). In both cases the point is simply that one is covering over something that will not endure (earthenware) with something that makes it look better than it truly is. The reality is concealed. It is a ridiculous covering of earthenware. It is, in fact, a waste and deceitful. Its apparent value is only that…appearance. It is a cheap object made to look like it is worth something far more.
K. L. Barker, “The Value of Ugaritic for Old Testament Studies,” BSac 133 (1976): 128-29.