Over time, cracks appear in the caulking by the trim, because the wood shrinks as it dries out in the low humidity in the house during winter. The dark cracks can look quite unsightly, especially if they are large. This first set of photos below show only a small crack, because I forgot that I was going to take photos of the process until I was almost finished with the caulking.
Step 1: using an old paint brush (or other soft brush), thoroughly brush off any dust (or dog hair!!!) from the area to be caulked.
Step 2: apply paintable latex caulk to the gap. I was mostly filling only small gaps, so I cut a very small hole in the end of the caulking tube. Use a wet finger or cloth to smooth the caulk and clean up any excess.
This is what it looks like after the caulk is applied. The gap is much less noticeable, isn't it?
This was a larger gap on the trim of the stairs. This is before being caulked (obviously!).
This photo shows what the stairway looks like after it was caulked. The caulking shows up well with the camera flash, but once it is painted it will all blend in and nothing will be noticeable.
Here I am painting the caulk with a Chinese trim brush. I thought I would try this kind of round brush as it is supposed to be excellent for things like this. I need to do some more painting with it to get more practiced before I can decide if it is better than the standard flat brush.
I just realized that I didn't take any "after" photos. That is because as soon as I was finished painting, Freda and I went off to Kelsey's to enjoy their free chicken wings - that was a 30th anniversary promotion. And it was very tasty too. I thought this view was very pretty, but the camera didn't render it very well. I had to adjust the original photo to darken the photo as the camera rendered the sky too light and the neon lights on the building across the parking lot are over-exposed.