How to get sun artifacts?

I see on expeditions never dannig, always the other merchants appear. How can you obtain sun artifacts?
In the acts I have met him and obtained some sun artifacts, but now I am already at yellow maps and never get sun artifacts.
How can i get the sun artifacts when in maps?

1. Be lucky
2. Don't be unlucky

(In all seriousness, the more you play, the more pulls of the slot machine you get, the more the Law of Large Numbers comes into play. You just have to play more and Dannig will show up now and then. Play 10 Maps, maybe you get unlucky and never see Dannig. Play 100 Maps, you'll almost certainly see a Dannig. Play 1,000 Maps and I'll eat my shoe if you don't see any Dannigs in any 1 of the 1,000).

I have done approx. 70 maps now, so maybe he will appear soon...?