Twig/Willow furniture---Have a set. Always under covered porch. Now--outside. Any preservative I can use?

I've treated mine with Thompson's water seal since I first purchased it years ago and it still looks like new. I did skip one year (unfortunately) and was told to use deck wash (diluted) to lighten up the darkened apperance and sealed as usual. Most important thing is to completely drench ALL areas including underneath and the bottoms of the feet. This tends to keep insects away which can comepletely ruin a good set.