I have tested a lot of strippers for wood decks and fences over the years, and my preferred product is Rip It! from Sun Brite Supply. When I estimate a deck for a customer, I always keep some of this stripper mixed in a spritzer bottle and spray a little in an obvious spot. I let it sit for a few minutes, and then scrape the surface. If I get a goo with some color in it, I have proved to myself that the old sealer is an oil and can be stripped easily with the Rip It! product. If all I get is a clear liquid when I scrape, then the old sealer is a water-based product and a caustic stripper won't work. A lot of times I decide not to do a job with a water-based sealer already on the wood. There are some cool strippers out there for latex and acrylic sealers, but they can be pricey and a lot of customers don't understand why there is an extra charge. I hate those Do-It-Yourself sealers from HD.
