Best Way to Seal Hollow Core Door

Some kids set my backyard on fire New Years Eve and it ended up melting my big resin table along with the 6 chairs that went with it. I used this table as a potting bench and I'm going to miss it terribly in about a month.

I was considering using a hollow core door on saw horses to replace it. I'd like some suggestions on the best way to seal it so it won't warp or disintegrate from rain. I don't think that water seal stuff you put on decks would be enough, or would it?

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