Mechanism of formaldehyde / phenol condensation
@Harry Holmes: Here is a simplified example of how the formation of Bakelite may occur under base-catalyzed conditions to incorporate formaldehyde as -CH2- at the ortho and para positions of phenol. There are a myriad of permutations as to the order of condensations. I have selected one that illustrates the Michael-like addition that seems to have eluded you.
Phenoxide 1 adds to formaldehyde at the para position in what amounts to the first step in an aldol addition. The addition is likely adding to the ortho position of phenoxide as well. Species 3 may condense with phenoxide at this point but I have chosen to incorporate two more equivalents of formaldehyde at the ortho positions of 3 to form 4. Now elimination of hydroxide from any of the three positions of 4 leads to a Michael acceptor, such as 5, which reacts with phenoxide or any substituted phenoxide having an open ortho or para position. Structure 6 simply illustrates the mechanism for incorporating formaldehyde. The o-methylenedienone 5 is the product of an aldol condensation wherein phenoxide is the enolate.