Chosen Solution
What material does Apple use for the black border on the front panel between the plastic sheet and the thin galvanized steel? What coating or surface treatment do they use that both bonds to plastic, and provides a surface for a strong adhesive bond to galvanized steel?
OK now I have a better idea what your question is. The cover glass is painted with a coat of dense paint so if you’ve damaged it it’s not easy to patch as the shade of black might not match up. Here’s the part number for the cover glass if you want to just replace it: iMac Intel 20" EMC 2266 Glass Panel, Apple P/N 922-8848
