Once all the stones are placed, double check the weather. Do not proceed if you anticipate rain or freezing temperatures within eight hours.
Check the bottom of the plate compactor for rough spots or gouges that might damage the stones. Tape thin cardboard to the skid or lay a tarp over the stones if damage is a concern. Run the plate compactor over the cobblestones in an opposing direction, making sure not to drag the plate and move any stones. Next, mask off any adjacent areas for protection against grouting; lightly hose down the stones with a misting nozzle.
Make sure the inside of the concrete mixer is clean. Mist the inside of the drum, then pour in one 50 lb. bag of sand and start the roller. Empty one set of the two-part epoxy into the drum. Fill the set (two bound bottles) with clean water and pour them into the drum. Mix for two minutes or until the mixture looks like wet oatmeal. Pour the mixture into the 5-gallon bucket and spread at the far end of the cobblestones. Have one person mix and transport the grout and one spread it.
With the foam squeegee, work the grout into each joint thoroughly using an even downward pressure (similar to grouting tile). Slowly work across the area to the other side. Work as much of the grout off the surface of the stones as possible. Do not walk on newly grouted areas, as stones may shift and create voids between stones and the grout. Once all joints are completely filled, clean up any excess and allow to set until firm. Once the grout is firm to the touch, broom off any remaining sand from the tops of the stones with a still-bristled push brush. Avoid foot traffic on the cobblestones for five hours and vehicle traffic for 24 hours.