What’s the Best Everyday Base Layer?

I live in a place where it gets cold, and I tend to be cold. I like to wear a layer under sweaters for additional warmth, but it is hard to find long-sleeved items that slip easily under another garment, aren’t visible at the neck and add some additional warmth. Do you have any suggestions? — Kate, Wilton, Conn.

What you are talking about is, of course, that item that once upon a time was known as “long johns” or a “union suit” or “long underwear,” and is now mostly referred to by the more socially acceptable name, “base layers.” Base layers suggest clothes that at least have the potential to be seen by others, while also implying some sort of hiking-skiing-climbing association.

And as with most fashion items in which the terminology has evolved — see, for example, the way used and secondhand clothes became “gently loved” and “vintage” — so, too, has the choice. Base layers now come in so many different materials and prices (SmartWool! Synthetics! Merino! Silk!) that confronting a shelf of potential tops can feel as intimidating as scaling Denali.

OK, not that intimidating, but everything is relative.

Which option is best depends on the purpose for which it is meant. A good guide to the minutiae of base layers for both women and men can be found here, courtesy of my colleagues at Wirecutter. But for your purposes — keeping warm during everyday life as opposed to engaging in performance activities — many experts agree that merino wool tops the list.

According to Brian Anthony, the head of merchandising for Houdini, an outdoor brand based in Stockholm, “the natural properties of merino manage the ‘microclimate’ of our clothing systems, keeping you warm but not overheating. They can also be worn repeatedly without retaining odor and dry pretty quickly.” Eoin Comerford, the chief executive of Moosejaw, an online retailer, agreed.

Then the question becomes one of style: Do you want a layer that looks gym-ready? Vintage? Or do you want one that’s more like a thin T-shirt (See this top from Icebreaker, which has a V-neck.)

You can find merino versions of all of the above, but for anyone with less technical needs, another good option is silk. It’s not as effective as wool or synthetics, but it feels a little dressier and more urban, less into-the-wilderness. Both L.L. Bean and Land’s End are great resources.

Then there’s this Uniqlo x Marni color-blocked Heattech turtleneck, which is synthetic but silky and can go pretty much anywhere. Admittedly, it’s visible, but in a good way.

Finally, if you want something that truly lies flat against the body, doesn’t create bulk and can be worn with suits or dresses, nothing beats a bodysuit. Intimissimi offers a simple scoop-neck style in a cashmere modal blend (modal is a fabric made from beech tree pulp), and if you want a holiday splurge, look at Commando and the Wolford outlet.

The prices may seem outlandish for something that most people will never see, but this is one item that never goes out of style. It also makes a great last-minute gift. It’s a little splurge that may seem too pricey to buy for yourself, but the items provide secret confidence and comfort. The value proposition is just … well, basic.

Your Style Questions, Answered

Every week on Open Thread, Vanessa will answer a reader’s fashion-related question, which you can send to her anytime via email or Twitter. Questions are edited and condensed.