So you need the facts before you shop. We spoke to Rupert Burton, chief designer for Van Heusen and Davenport underwear in Australia

COTTON ON

Which underwear trends withstand the test of time?
"New fashions in underwear are often geared towards the youth end of the market. Research shows that by the time a guy reaches the age of 40, he stays with one kind of fit and usually the same brand, so labels tend not to change the fit of their basic shapes very often. And about 90 per cent of underwear sold is cotton (or a high-percentage cotton blend), while the No.1 colour sold is black, followed closely by navy and grey - this never changes."

CUTS IN BRIEF

Briefs (jocks) versus trunks (short shorts) versus boxers. Talk us through it.
"It's down to personal choice. As a general rule briefs are going to give you the best support as they hold everything in place. Recently there's been a lot of experimentation with the fit of briefs - from super-low-rise shapes to brunks (cross between a brief and a trunk) so now there's something out there for everyone. Boxers have also seen a resurgence with new low-rise, slimmer fits, as brands have realised the trend for slimmer jeans meant people didn't want metres of fabric under their pants. So briefs and trunks will give you the best support, while boxers are best if you want things to feel a bit looser."

TAKE A BREATHER

Which materials breathe best?
"Cotton or cotton blends breathe the best. They're also the best in terms of washing and drying performance. Other natural fibres like silk or bamboo are good as well. Many brands use technical yarns such as Coolmax or RealCool Cotton that are a blend of different yarns - usually cotton and polyester. These are designed to keep you cooler by wicking the moisture away from your skin to the outside where it can evaporate. They're good, but you still can't beat cotton for everyday breathability."

MATERIAL WORTH

Which fabrics survive tumble dryers?
"Most cotton and cotton blends are fine in the tumble. But make sure it's on a cool setting, and don't leave them in the machine after they're dry. Never put silk undies in the tumble dryer, and try to dry polyester or nylon fabrics normally."

STRETCHING IT

Is elastic the weakest link in underwear, the bit that 'goes' first?
"Elastic can be the weakest link, but mainly when it's not washed or dried right. Elastic is made from rubber or latex which will naturally perish. Perishing is made worse by exposure to heat, so drying your undies naturally and out of direct sunlight helps them last. When buying, check that if there's an elastic waistband it's attached to the fabric with at least three rows of stitching. One panel constructions (so there's no side or back seams) also tend to last longer as there's no chance of seams twisting or being pulled apart."

BULK-BUY

Most guys go for the 3-for-1 deal. Should guys spend a bit more and seek out better quality?
"Most guys hate shopping. When you see a multi-deal on undies it doesn't mean the quality is bad, it just recognises that guys want to buy their favourite style or brand in bulk and get out of the store quickly. It's great for everyday wear, but we are seeing a trend towards guys also having a few 'best' pairs for special occasions or nights out. It's here that they can spend more time in the store and invest in more expensive brands."