Manufactured from man-made yarns, synthetic base layers are usually knitted from yarns of polyamide, polyester or polypropylene, and sometimes a combination (blend) of two or more. Occasionally a small percentage of acrylic is added, but these are usually on cheap products that probably will not make it past a few washes anyway. If you have a base layer that is a blended yarn of both natural and man made fibres, then the washing instructions are usually more comprehensive.
FOLLOW THE MANUFACTURERS INSTRUCTIONS
Care labels on base layers are there for a reason i.e. to be followed. They are not rough guidelines for you to interpret how you wish. They provide instructions for the maximum levels of certain processes such as wash temperature, and processes that shouldn’t be used, such as ironing and dry cleaning.
For a handy guide to wash care symbols please visit the Love Your Clothes website
The harsh chemicals used in the dry cleaning process will strip out any treatments on the yarn such as softeners and hydrophilics, and the drying process can lead to shrinking and melt spots, so don't even think about taking your base layers to them.
Using detergents are a bit of a grey area as it depends on the yarn content of your synthetic base layers:
Polyamide base layers, such as our Factor 1 Plus, have a hydrophilic chemical treatment pressure injected directly in to the yarn during the dyeing and finishing process. It is not everlasting but it takes a very long time for the treatment to be washed out, even when using fabric detergents.
Polypropylene base layers very rarely have any treatments applied to them due to the yarns properties, so washing machine detergents can be happily used on them.
Polyester base layers often have softeners and hydrophilic treatments applied to the outside of the yarn. These are easily stripped out by washing detergents so you may need to treat them every few washes with a dedicated base layer treatment wash.
Generic fabric softeners sold for everyday household clothing so not be used on a base layer wash. They coat the fabrics fibres with a waxy finish that affects their moisture transportation capabilities. If you should use a fabric softener by mistake, then just rewash the base layer with a normal detergent.
It is always a good idea to separate light colours from dark colours in any wash if you want your whites to stay bright. Some clothing colours will leach in a wash leading to colouration of lighter garments if mixed together, especially base layers manufactured from polyamide yarn. Polypropylene base layers are usually resilient as they do not absorb any moisture, so can be mixed with different colours. If you are in any doubt, then use a colour absorbing sheet in your wash.
If you are intending to mix garment styles in a single wash then be aware of the possible consequences. Any jacket or trousers with either a zip or Velcro fastenings could potentially damage your base layer during the washing process. The hooked harsh face of Velcro can be especially damaging as it catches the base layers fine filaments and can lead to pulls and ladders. It is always a good idea to wash Velcro and zip containing clothing separately, with the zips fully closed and the Velcro fastened (if possible).
Most dedicated synthetic base layer washes and general detergents will work perfectly well on a low temperature setting such as 30ºC. Even if the care label states a higher wash temperature tolerance, it is not a requirement to get synthetic base layers clean these days.
Some people advocate washing synthetic base layers by hand in cold water, but this is time consuming and unnecessary for most garments. If in doubt, check the neck label.
Using a tumble dryer to dry synthetic base layers is best avoided as they can be unpredictable and untrustworthy. Most base layers that shrink in tumble dryers are not down to the heat, but the length of time they are left in the dryer. If you do need a base layer quickly out of the wash, then set the tumble dryer to the coolest setting, remove any collected lint from the collection screen, and keep an eye on it. It is better to underestimate the time and keep on adding small increments after checking the dryness.
Shrinking your synthetic base layers in a tumble dryer is not reversible.
Again, ironing synthetic base layers is best avoided. It is very easy to use the wrong temperature setting when ironing a pile of clothes, and an iron on a high setting will glaze some synthetic fabrics and will melt others. If you hang them up tidily for drying and then fold them neatly when dry then creases will be avoided. In any case, who is going to see your base layers when you are outside anyway.
WORD OF WARNING
If you do wash and launder your synthetic base layers incorrectly and not according to the instructions, and something does happen to them such as a shrinkage or a deformity, the manufacturers will know it is your fault. Fabrics are so stable these days and manufactured in such high quantities that one bad item out of a batch of thousands is going to stick out like a sore thumb. The best tactic is to stick your hands up and admit you made a mistake, and if the manufacturer is half decent, they may give you discount off a new set or exchange the base layer in exchange for some PR material.