Yes Donna you can use poly over chalk paint. If your chalk paint brand sells a coordinating clear finish I would consider buying the same brand name product. I have had issues with using a different brand poly over SOME chalk paints. Bubbling and stippling. With SOME chalk paints it doesn't matter which poly you use. If you are using poly over a white chalk paint I would suggest using a water based poly--Minwax Polycrylic is one brand--so that the poly doesn't yellow over time. You CANNOT poly over wax however--so if you have treated your project with wax first the poly will not adhere.
Thanks I’ll try it on a sample first.
Yes, but use with caution. Polyurethane is a seal-the-deal kind of finish, so it’s best for table tops, areas susceptible to sticky little hands or liquid spills, and of course your outdoor furniture. Polyurethane is very messy (smelly, too) and since it’s oil based, be sure to you have paint thinner on hand, or you’ll ruin your paint brush. I only recommend using this if you are wanting some serious protection on your kitchen table.