Your plan is good, but not the product. Home Depot does not sell polyurethane for concrete coatings. They carry polyurethane for wood floors and furniture. Varathane and polyurethane by Minwax are examples. They are amber in color and not compatible with your coating.
I suggest you use the same product that was used on your floor originally or purchase some polyurethane from one of the vendors that participate on the GJ.
Call both Legacy Industrial and Garage Flooring LLC. I believe one of these GJ vendors sells it in quart kits. Give them the info on the current product you used to make sure there are no compatibility issues.
Correct, have quart size for all the clears.
Correct, have quart size for all the clears.
