[quote=loneframer;647193]Just by the stated weight, that is not MDF.
Most likely it's a polyurethane foam, such as Fypon."
If it's polyurethane foam would it have a pattern of extremely (and I mean extremely
) fine diagonal lines on the medallion face? The back is definitely some kind of foam, and does not have the diagonal pattern but the face does. Dang near have to hold it up to your face to see it, but it's there. Whatever it is, it sure is light. The factory specs said it only weighed 0.44 lbs. I estimated about 0.6 lbs above because I glued on the 16 rectangular plastic pieces to give me more adhesion surface area.
I welcome any other opinions or posts from people who have installed a ceiling medallion
(BTW, thanks for schooling me on what MDF is. I looked MDF up on Google and learned it is made from wood fibers and more dense than plywood. Like you said, definitely NOT MDF. Knowledge is power, eh?)