 If it's cleaning it, stay right there, 18 inches away. And then depending on the type of sealer you're going to use, you're going to want to have that dry out for a while. If you're using a latex, you could probably do it within three hours on a hot day. But before you do that, you better read the instructions on the deck sealer too. There'll be some limitations on that. Maybe above 90. You don't want that wood to be above 90.