Hi, Sarah!
In 2009 when I was planning my first Camino, I read about merino wool here on the forum as a new member, and decided to take a chance and buy a couple of Icebreaker shirts to try (I happened to visit Toronto and was able to get a great deal at a factory outlet shop there). I loved them right away and took Icebreaker shirts and leggings with me on that first Camino in 2010. I've since had almost all merino wool clothing (including socks) with me on my five Camino walks at different times of year.
I hand wash my merino clothing on the Camino (except for two or maybe three times along the way when I choose to use a washing machine -- I am wary of any machine that won't wash on delicate, and at home I use the delicate cycle on my machine; and I never put them in a dryer). I use either Dr. Bronner's Baby Mild Unscented liquid soap, or Ecover liquid dish soap. And I hang them to dry. This was tricky the first two times I walked, in September-October, as the air was damp most days and there was less heat from the sun, and we had frost by the end. Sometimes I ended up wearing the shirt I'd washed the next morning, putting it on damp and letting my body heat dry it the rest of the way. Or there were days I decided not to wash my shirt at the end of the day and just keep it on for the next day (merino is fabulous in that it doesn't need to be washed daily and it doesn't retain body odor -- most of the time it airs out beautifully in next to no time
). You will likely find that you smell a bit like a wet sheep if you wear it before it's completely dry (or if you wear it in a rainstorm for example).
The other three times I've walked were in June, July, and August and there was no trouble getting the clothes dry in the hot summer sun.
An annoying thing about merino is that depending on what weight you buy, it can develop teeny tiny pinholes quite easily. The 150 weight shirts are classic for this, especially if anything you're wearing, like backpack straps, rub it constantly. The sleeves of my shirts have developed holes in the upper arm, on the underside, where the backpack strap rubs. It's more a cosmetic flaw, but the holes can stretch and spread over time. I carry a needle (in my foot care kit) and in addition to white thread for that, I bring a small amount of thread the same colour as my shirts so I can mend tiny holes as they appear. The 200-weight-and-up fabric is more robust in general.
About two years ago I decided to branch out and give Smartwool brand a try. I'd read that it wasn't as durable as Icebreaker, and that may be the case for some pieces, but I now have a few Smartwool shirts I love, and I live in them daily pretty much year round now. As for my original Icebreaker clothing from 2009 and 2010, I have two shirts left. They've lasted a good long while! And I still have my leggings from 2011, though one pair has some holes from brambles on top of the hill by the lighthouse in Fisterra. Beautiful memories!
Buen Ca-merino!
Rachel
P.S. Somewhere, sometime, I read not to mix wool and baking soda (it does something to harm the fabric apparently) so I never use it in a wash cycle with merino clothing.