Dan, you are 100% correct, the fouling here in the summer, when the humidity is the highest is gooey, like wet tar and does require constant wiping around the pan, flint and frizzen. The club I used to shoot with used to shoot early in the morning so the temperature and humidity were often intimidating to say the least. The guys that shot caplocks often had more trouble in matches due to fouling and that damp buildup in the drum and breech area than us flinters since we pick our vent holes every shot. I have only gotten that white caking you show in your photo in cooler, drier weather. Other times, it is usually black and damp appearing. Another big problem here in the summer is that your perspiration rusts everything even more than the powder residue. I am not kidding about that. I often finish rifles in the white, and when I had to go to a range to shoot, after a long match or shooting session, by the time I got home, there was an area of rust already forming on the areas of the barrel where the barrel was handled the most. That required rapid removal and oiling to stop or it would be hard to handle later. Some of the other guys I shot with, that had commercial guns with factory blue finishes would get that as well, although obviously not as badly. I finally caved and started browning almost all of my barrels and avoided that.