Fastener assembly with improved temporary attachment layer

In an elongate fastener assembly comprising a polymeric backing strip having first and second major surfaces:

• a multiplicity of stems each secured at one end to said backing strip, projecting generally normally to the first surface of said backing strip, and having enlarged heads at their ends opposite said backing strip adapted to engage loops on materials pressed against said heads;
• an open porous permanent attachment layer attached to the second major surface of said backing strip, said permanent attachment layer having sufficient open areas to afford movement of foam into said permanent attachment layer to permanently attach said fastener assembly to a foamed article;
• and
• a temporary attachment layer comprising ferromagnetic material sandwiched between the second major surface of said backing and said attachment layer, said temporary attachment layer being adapted to be attracted by magnets to temporarily hold said fastener assembly in position during the foaming process;
• the improvement wherein the temporary attachment layer comprises ferromagnetical particles dispersed within a polymeric bonding material, said bonding material having generally the same coefficient of thermal expansion as said backing strip and exhibiting essentially the same shrinkage as said backing strip when said fastener assembly is exposed to temperatures around 125.degree. C., so that the temperatures resulting from the foaming process will not cause a substantial relative change in length between the backing strip and the temporary attachment layer.