Bad idea. Poly is not a good exterior finish. It does not expand/contract well, cracking instead. That negates the protection. Poly even with UV protection added can let UV rays bleach the color of the wood.

Hardwoods do not expand/contract with seasonal temperature/humidity changes at the same rate, possibly causing joints to open.

If you would like outdoor rockers, chairs made from Ipe, cypress, cedar, plus other woods do not necessarily need to be finished. They will turn a gray color and the natural composition of the wood resists rot and weather damage.

Painted furniture can be made of almost any wood---the paint provides UV and weathering protection.

Thanks handymac,

I was hoping someone would have answered my question before lunch which is when I went to purchase chairs. I went ahead and asked at Home Depot about chairs and they said the poly would be good and chairs should be fine so I bought some and a brush and headed to Cracker Barrel to buy the chairs.

Are you saying perhaps I should have bought the painted chairs (perhaps the white ones) and not the natural looking chairs? since I have the chairs, are you saying if I don't exchange that perhaps I can paint white?

Thanks!

Since you already have the chairs, try doing this. Take back the poly and get a spar varnish instead. Make sure it has added UV protection. That finish will add a slight amber tint, but is designed to take the temperature/humidity changes in outdoor environments. Spar varnish usually need to be redone every two to four years, depending on sun and weather exposure. That is basically a light sanding and recoating.

You can paint over any finish if you use the correct preparation. Lightly hand sand the previous finish---just to rough up the surface. Then use a primer like Zinsser Bullseye 123 primer and then the exterior paint of choice.