I'd like to know where you ended up with this. I live in RI and have the same problem. Bought and old house years ago, now have kids, and of course now radon is testing high. First thing I did was buy a radon monitor. It's called the "Corentium Digital Radon Gas Monitor". You can buy it online for $245. I've had mine for 6 weeks and has told me a lot about the radon levels in my house. Craziest thing is that radon levels fluctuate day to day and can vary a couple of points so the 2-day tests are in my view, worthless. Also radon levels vary seasonally. The best radon test is an average over a year, with a minimum reading of a week. What's great about a continuous monitor is that you can tell hourly if the radon levels drop because of your mitigation. FYI opening windows does work for about a day then they go right back up again; great for summer, chilly in winter. My basement is mostly old poured concrete (more like a rat slab) and I have some open dirt sections. My plan this summer is to take up the old slab and install a proper radon pipe grid, cover with gravel, then poly, then top with new concrete. That should give me a better, drier, basement and also eliminate radon from the slab. I'll pipe it for a passive system and if it doesn't work I'll add the fan. It's unlikely that you or I have a decent layer of gravel under the old basement slab so any point suction mitigation won't work. that works in newer foundations that have the gravel but not the piping. The second thing is a perimeter drain. This will relieve the pressure against the outside wall and vent the water and radon gas to daylight. Radon gets sucked through the rubble walls by stack-effect so I plan to put a layer of poly against the foundation to act as a vapor barrier, then a perimeter drain product by Eljen. Good luck, we'll both need it.

For the 4th of July: Although I don't agree with all of the discussions and professional mudslinging I do agree with this type forum and this great nation's ability to voice their dissent. It's only a deck and a quick question requesting the opinion of a seasoned, experienced, professional deck builder. To know that I have the ability to choose the method and product of my choice and to have several individuals gladly disagree in a public forum without fear of reprisal.....makes me thank all of the folks that have sacrificed their time and in many cases their lives to give me this freedom. Happy Independence Day!!

Thanks - my cousin the carpenter hasn't done much wood finishing, but he's had this problem - with darker stain so more noticeable. I wiped down with naptha, am going to give it a full 24 hours to dry and then decide what to do. The Natural stain is so light you can't see spots except at an angle, I just didn't want them to telegraph through the finish. I may end up sealing them with dewaxed shellac and then wiping on thin coats of poly over the shellac. I've never tried it, but have read that as long as it's dewaxed poly should stick - I'm starting a test on scrap oak right now. We're planning on Friday now to put everything up, so I have enough time for everything to dry. He even cut some custom oak cove for me this AM, since I couldn't find 1/2" oak cove in big box stores. I think this is going to look really nice when it's finally done - I have to get more oak shoe since I decided to use it instead of cove for a heftier collar at the top, but that can always be added later since it's got to go up (to hide the top lag screws) after the newel is secured to the wall.

millworkman, I think that many products are incompatible with others. I've used Thompson's WS on a covered pressure-treated deck for years... never had a problem, but it's the only finish I've ever applied to that deck. HU, I've been in that situation with cold and potentially wet weather vs a winter with no protection and I've gone with my gut. I've always been sure that the deck was thoroughly dry before applying anything though, and haven't pushed the limits too much on recommended temps, etc., so that it's readily absorbed into the wood. Be sure your wood is dry before applying the water seal and don't leave any puddles of the stuff and you'll lessen your chances of any problems.