A short note, as it's been a very long time since I posted anything here (or anywhere else) about log homes. Our is fine, in case anyone is wondering
We've been in the house 10 years, now. We originally stained with TWP 500 series and the first treatment lasted about 3 years on the upper floor. The lower floor is under a wrap-around porch and so gets no weather and only indirect sunlight. We refinished the upper floor after about 4 years. The upper floor looked darker than the lower floor for a month or so, but evened out pretty quickly (we use a rather dark color, Rustic Oak, so a 516 stain).
This time, we left the upper floor for about 6 years and the stain had pretty much failed; some mildew had started in a few places on the south-facing wall, which is full-log. The west wall (white cedar siding) had suffered some golf-ball sized hail driven by a 30-40 MPH west wind a couple of years ago. The siding was fine, but the finish suffered some light spots where the hail hit. What direct sun hadn't pretty much wiped out suffered some fading due to UV exposure.
I applied Log Wash the power washed it off with about 600 PSI at about 18" or so. This took off almost all the old stain on the upper floor and removed quite a bit form the lower floor, too. We had not washed the house in about 4 years, so it was quite dirty.
I found that the TWP 500 series has been replaced by the 1500 series, so I went for that. With daytime highs in the mid 60's here (central Oklahoma) application was as easy as the 500 series had been (I have a spray rig), though the 1500 series is just a bit more viscous. The stuff soaks in just as the 500 series did, and I did wet-on-wet on all of the upper floor. It wasn't necessary on the lower floor, so that was almost exclusively a single pass.
The 1500 series has a higher solids content, so I'm hoping it lasts a bit longer. I've gotten older far faster than the house has and this was not quite as much fun as I remember it being...
The finish is still "curing" and that's fine by me! It's perfect weather for this and it will stay dry for the foreseeable future, so conditions couldn't be better.
I noticed the lower VOC with the 1500 series stain: things didn't smell quite as bad in the house for as long this time around. Clean up is easy and the color remains perfect. We still need to do all the cedar posts that hold up the wrap-around porch roof, but the place looks great! I'll post some pictures tomorrow.
I want to make a shout out to Jon Fife who generously gave me lots of hints about refinishing these many years ago. Everything he told me has always been spot on and is as useful today as it was the first time 'round. Thanks, Jon!