How you launder your knits is best answered by the label that was
How you launder your knits is best answered by the label that was attached to your ball of yarn. It should contain the
international care symbols that apply to your fiber: image to right found at bottom of page. You should learn these symbols so that you know at a glance wether to dry clean or wash, the best water temperature, is bleach permitted, as well as the best drying technique for that fiber. If the item is a gift, include a label so that the recipient knows how to care for the item.
Should the label not be available, launder the swatch and check the results. Pre measure and check for shinkage. color loss, excess wrinkling, or any other laundry damage that can occur. If there is no swatch, then err on the side of caution!
In general, hand wash and line drying (lay flat) works for the vast majority of knits. There are very few yarns that allow for machine drying.
What is the fiber?
Cottons and silks tend to fade when machine washed and benefit from hand laundering. Dryers tend to make cotton shrink more, so again, line drying is usually better.
Wools felt or shrink under one of three conditions. Agitation, temperature changes, and alkaline solutions. Obviously a washing machine is a high agitation situation! Changes in water temperature will cause felting but taking a just laundered garment to a colder/warmer place to dry will also cause felting. Because Woolite is an alkaline solution, it too can cause felting.
Man made fibers tend to be more tolerant of washing machines but the high heat of dryers can result in a yarn that has been "killed". Even blocking with an iron not even touching the knits can result in a killed yarn. Killed yarns lose their elasticity and never get it back.
Exotic fibers, both animal and man made should be researched to find the best laundering technique recommended for that fiber. Cashmere shrinks readily as do many of the more exotic animal fibers.
With so much time involved in making a garment, be sure to investigate the best method of caring for your treasured piece.