Bondo All-Purpose Putty

Bondo All-Purpose Putty is a two-part polyester filler used on concrete for spot patching, small spall repair and filling static cracks before a coating goes down. It is a prep material, not a finish. Nothing about a patch matters except whether it holds, whether it grinds flush, and whether the coating on top of it stays flat and invisible six months later.

This is the material contractors reach for when a floor has a handful of divots, popouts or chipped control joint edges that need to disappear before a flake or solid color system is installed. Polyester fillers in this class kick fast and hard, which is why they show up in schedule-driven work. That behavior is typical of the chemistry rather than a published figure on this listing, so read the container and the manufacturer data sheet before you set your timing on a job.

Mix with Bondo Cream Hardener on a clean, non-porous board. The putty only works if the substrate is right: the repair area needs to be dry, sound, free of dust, oil, curing compound and loose material, and mechanically opened up so the filler grabs something. Grinding or wire brushing the patch area first is standard practice. A patch placed over dust is a patch that telegraphs.

Once the filler is hard, grind or sand it flush with the surrounding slab so it does not print through the finished coating. Any high spot you leave is a high spot you will see under gloss. Feather the edges, vacuum the dust, and confirm the coating you are installing is approved over a cured polyester filler before you commit the floor. Manufacturers differ on this, and it is a question worth asking us at 817-676-6793 rather than guessing.

Moving cracks, joints that are still working, and slabs with active moisture are a different problem. Those need a flexible joint filler or a moisture mitigation system, not a rigid polyester patch.