I have two merino baselayers and find that they make me really itch, mainly across my chest so they get very little use, in fact I wish I had never bought them. I only use them when I have no choice for running when all of my other tops have been used, are in the wash, or are still drying. When I know I'm going to use my 'itchy' I travel to my run start point wearing an old black pyjama top, it looks like a 'T' shirt and on arrival, I put the merino on. I can run for up to an hour (assuming the air is cool) before the itching really starts, across my torso and underarms mostly, and when I get to my end of the run point I quickly take it off and put the pyjama top on again to travel home in.
I'm really hopeful that I can now begin to wear my merinos regularly and get proper use out of them. For the last two days I've worn my Brynge 'string vest' and my merino baselayer over the top of it. I've then gone running, sweated a lot and surprise, surprise, no noticeable itching! I'm now hopeful that because the merino wool is not really touching my skin in the same way anymore, I will be able to get full and better use out of them. Will I ever take them on a multi-day hiking trip? I'm just not sure yet but if by running use, with the aid of my Brynge string vest and my itching problem really is solved then I might.