Gear review: Summer base-layers

I’ve not known a Scottish summer to be as warm as this one so far… and it’s provided the ideal conditions to test out a range of lightweight baselayers. Summer t-shirts for walking are generally one of two fabrics these days: polyester and merino wool (it’s important to avoid cotton which traps moisture next to the skin, becoming cold and uncomfortable). Polyester and merino wool have their advantages and disadvantages; polyester is lighter, cooler, cheaper, quicker drying and more durable, whilst merino wool is softer to touch, requires more care when washing, is warmer, less durable, more comfortable when wet, more expensive but gets less smelly with multi-day use. All of the garments tested are also available in women’s versions.

Patagonia Capilene Lightweight T-shirt

Recommended Price: £37
Fabric: 100% recycled polyester, polygeine treated

Polyester, being derived from petroleum, is often regarded as the less ethical choice, but this extremely lightweight tee shirt (just 77g) is made from 100% recycled material and the sewing process is fair trade certified – as you’d expect from a company with Patagonia’s environmental credentials. The fabric has also been treated with polygiene which inhibits the growth of bacteria that cause smell; similar treatments have been around for several years that help to stop polyester garments from smelling, but we’ve found that polygiene continues to work well even after many washes. The shoulder seams are offset to ensure comfort under your rucksack straps. The Capilene tee is available in grey, black and dark blue as well as the striking orange pictured. With such a thin fabric I’ve found it extremely comfortable to wear on the hottest days – it also dries incredibly quickly when you take your pack off for a break.

Icebreaker Sphere short-sleeved crewe

Recommended Price: £55
Fabric: 52% merino wool, 35% TENCEL, 13% nylon

Icebreaker is a New Zealand-based brand which specialises in high-end merino clothing. This crewe shirt is actually made from the Cool-Lite fabric, which combines merino wool with tencel (a wood fibre) and nylon, and is intended for the warmest weather conditions – Icebreaker claim it wicks moisture away from the skin three times faster than merino wool alone. It feels the most luxuriously soft to touch out of these garments, and is very comfortable against the skin even when it starts to get wet from sweat. It’s performed very well on the hills during the recent heat wave.

Alpkit Koulin Trail tee

Recommended Price: £18
Fabric: 100% polyester, polygeine treated

This has a quite a different design to the other t-shirts on test, with a large mesh panel across the rear designed to maximise performance under your pack, as well as under the arms. This helps prevent the Koulin becoming too warm on hot days, compensating for the heavier weight weave found here compared to the Rab or Patagonia polyester garments. Like them it has been Polygiene treated to minimise smells for multi-day use. An unusual feature is a small pocket into which you can slide a credit card or something similar. Alpkit are known for combining reasonable prices with good performance, and the Koulin Trail tee matches up to that. It’s available in two shades of blue and also forest green.

Rab Interval Long-sleeve Zip T

Recommended Price: £40
Fabric: 100% polyester, polygeine treated

The interval long-sleeve zip T is made of a very similar ultralight polyester as the Patagonia Capilene, and is also polygiene treated. The main differences are in the design – this has a front zip which can allow for increased ventilation. There’s also a stand-up collar that can help to protect against sunburn around the back of your neck – which combined with the long sleeves make this the ideal option for long days of strong sun. As well as the ‘Amazon’ colour shown here, the Interval is available in grey (‘ebony’) and dark blue (‘ink’); it is also available without the zip (£35).

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