Filler composition indicating readiness to sand

A process for repairing a vehicle body comprising:

• mixing a part A comprising a curable resin having a degree of unsaturation and a monomer reactive diluent in which the curable resin is dissolved or suspended, wherein the monomer reactive diluent is selected from the group consisting of:
• acrylic, acrylate, methacrylate, ether monomer of the structure (C1-C6 alkyl)-O—(C2-C6 alkylene), styrene, α-methylstyrene, vinyl toluene, di-functional styrene, allyl substituted benzene, di-vinyl benzene, difunctional acrylate, trifunctional acrylate, acrylonitrile, mono-vinyl-terminated polydimethylsiloxane, and combinations thereof;
• a part B storage-separate, free-radical cure initiator package comprising a free-radical cure initiator and a first fast pigment or dye in the part B to visually show a user when parts A and B have been uniformly mixed;
• and one or more color changing dye present in only the part A, the one or more color changing dye are adapted to change from an initial color to a terminal color upon mixing of the part A and the part B to form a homogeneous mixture;
• applying the homogeneous mixture to the vehicle body to a thickness to fill a surface imperfection therein;
• and
• curing the homogeneous mixture to form a fill to repair the vehicle body under conditions adapted to cause the one or more color changing dye to change to the terminal color within ±5 minutes of cure of the curable resin to a sandable condition on the surface of the mixture.

A vehicle bond filler formulation comprising:

• a part A comprising a curable resin having a degree of unsaturation, a monomer reactive diluent in which the curable resin is dissolved or suspended, and a hollow microsphere filler, wherein the monomer reactive diluent is selected from the group consisting of:
• acrylic, acrylate, methacrylate, ether monomer of the structure (C1-C6 alkyl)-O—(C2-C6 alkylene), styrene, α-methylstyrene, vinyl toluene, di-functional styrene, allyl substituted benzene, di-vinyl benzene, difunctional acrylate, trifunctional acrylate, acrylonitrile, mono-vinyl-terminated polydimethylsiloxane, and combinations thereof;
• a part B storage-separate, free-radical cure initiator package comprising a free-radical cure initiator;
• and
• one or more color changing dye present in either the part A or the part B in the form of a solution, the one or more color changing dye are adapted to change from an initial color to a terminal color upon mixing of the part A and the part B to form a mixture—spread on a vehicle body substrate to a thickness to fill a surface imperfection therein, where the terminal color results within ±5 minutes of cure of the curable resin to a sandable condition on a surface of the mixture.