I started this thread on 1/28, but the dressings on the tires were applied a few days prior to that. It has now been 14 days since the tires were scrubbed clean and coated with dressings.
Because I do expect fairly long durability for both dressings, I initially hadn't planned to post any updates for at least 3 weeks. However, the car has been driven in drizzle and light showers the past 2 days, so this would be a good time for an initial update.
Here is a 50/50 shot, with the GG on the left and GG topped with Tuf Shine on the right:
Both sides are not quite as nice-looking as when first applied, but overall still looks good. However, the GG side shows a bit more fading than I had expected.
Here is a shot of the R front tire, which was coated only with Tuf Shine:
What I want to highlight in this shot is that ther are areas (look at "91H") where it looks like some of the coating has already started to come off. This isn't be best shot, but the area actually looks somewhat brownish. This was very surprising to me, since Tuf Shine is expected to last several months. Although I went through 5 steps to clean the tire, it is possible that some of these areas did not get completely clean, so the coating on those dirty areas did not properly bond. Another possibility is that road debris may have scuffed the tire. But you can see that the gloss on most of the tire remains intact.
Keep in mind that these two pictures were taken at different locations in different lighting conditions, so a direct comparison between the area with GG topped with Tuf Shine vs. Tuf Shine alone can't be made based on these photos. I just took these photos on the fly with my cell phone.
I am previewing this post, and for some reason the pictures aren't showing up (just as with the initial post). But hopefully tomorrow one of the site admins will fix this problem.