I’m looking for a durable finish for Texas outdoor furniture using round reed & binder cane. It will be in the sun & weather. No paint.

The only thing you can tell them is you cannot guarantee the longevity as it is not how the product was intended to be used. Correct that a marine spar varnish would extend it, but still...no guarantee. A lot of our weavers just refuse work if it is to be left outside. I had a customer with 4 reed porch rockers and she was going to paint them (so reed, not binder cane)...I told her to do them quickly, she changed her mind and decided to seal them natural color...but waited and they got mold spots. Hard to see but...I gave her complete instructions. Sue