I have a couple Odlo merino wool base layer tops, and I noticed one of them has a couple little holes. I haven’t worn it since I spotted them, because I want to stop them from getting any bigger. Any tips/advice for patching these i.e. best thread, best stitch, etc.?
Wish I did. I've had the same problem on a few different merino base layers.
Right there with you @andr3w1sh & @TomIrvine . In my case, it's REI Coop merino t-shirts. One concern I have over using an improper, or amateurish repair method is that it could create a source of skin irritation on the shirts.
Come to think of it, I have had some success repairing holes in wool sweaters. One of 'em you can't even tell, and I'm no expert with the needle and yarn. I got my advice from browsing YouTube videos.
Anyway, I bet I could use the same technique on merino wool, just use lighter yarn. Basically you just work from the strong, undamaged part of the knit and criss-cross the hole. Some magnification would probably be handy for something like a light base-layer knit. Worth a try.