I saw a merino blended set of baselayers while at Costco yesterday that prominently mentioned the benefits of merino while leaving the poly fiber content in the fine print that got me thinking that could be the best of both worlds. Or it could just be another marketing ploy, can you combine the benefits of both man made fiber and merino?
This is a timely question as I bought a 50% Merino / 50% acrylic light sweater at a thrift shop this weekend and I was wondering how it was going to work out. I'm curious to know what other people's experience is. I'll let you know how mine works out once I have a chance to try it. I will say this, these blends can obviously shrink in true wool fashion because the one I bought is tagged as XL and it fits skinny small-to-medium me quite well.
I ended up buying a pair of bottoms at Costco that are 15% merino, 85% poly and wore them in today under a pair of nylon pants. I was nice and warm during the 39 degree commute, and didn't notice any shrinkage of any sort....
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I'm no expert, but based on my personal experience, I favor stuff with the largest possible percentage of wool in the blend.
I tried some Wigwam merino/silk blend socks (mine are 30% merino, 8% silk, the balance is synthetic), and with respect to insulation power, I found they were far less effective than the Defeet Blaze (63% merino). Part of that is probably due to the thickness of the socks (the Defeet Blaze is thicker), but I don't think it is a coincidence that the warmer sock has more merino in the blend.
I tend to prefer clothing with a light blend of synthetic in with the wool. The synthetic is stronger and more durable and tends to protect the wool a bit. They also don't seem to shrink nearly as much as 100% merino shrinks. I have some Ibex clothing that is wonderful to wear but after a couple of years they wear out. Some of my thrift store finds with 50% synthetic and 50% wool I have had for 5+years of wear and tear and still usable.
There are many grades of Merino and only the very best superfine grade is suitable for athletic base layers. A lot of Merino claims to be superfine but is not. Synthetic mixes are another way of cheapening the product. Genuine superfine merino is not itchy, does not pill or shrink and is very durable. Mine has lasted 3 years of regular use so far.
If you just want a midlayer, then normal grades of Merino are fine.
Socks are a bit different to base layers, they need to be much more durable so adding some synthetic makes sense.