After you have invested a great deal of time into knitting a sweater, you want to give it a beautiful finish. This often involves blocking the sweater to the proper dimensions. When you block a sweater, you are setting the stitches and evening out the fabric in addition to preserving the correct sizing. Generally, sweaters can be wet blocked (good for cotton and linen), spray blocked (good for wool and alpaca) or steam blocked (good for wool and alpaca) depending on their fiber content.
If your garment is going to be pieced together, you should block the pieces before sewing them up. This will help you to line up seams and to even out the garment to make the joining easier.
After subsequent wearing of the sweater, wash the garment as the yarn label indicates. To recreate dimensions that may have been lost during laundering, reshape the washed garment and dry flat.
You should always consult the washing instructions for your yarn before blocking or washing your sweater. It is also a good idea to test your blocking method on your gauge swatch to see the results before you begin on your final project. Blocking works well on animal fibers and cotton, but is often unnecessary with synthetic yarns.
To wet block your sweater you will need several colorfast towels and a surface that you can sink pins into. Soak the sweater in some cool water until it is thoroughly saturated. Use some no-rinse wool wash if the garment needs to be cleaned. (This helps conserve water and reduce hassle!) Lay the garment flat on a towel and roll the towel up. Step on the towel to gently press out excess water. Do this twice if the first towel does not remove all of the excess water. You want the sweater to be damp, but not dripping wet. When you have pressed out as much water as is appropriate, spread your project on a dry towel (or on a blocking board). Smooth out the fabric and gently coax your project into the desired size and shape. If you need extra help stretching your sweater, use some pins to secure the perimeter of the garment. Remember, don’t stretch out any ribbing while you are blocking as it will lose its elasticity.
To spray block your sweater, you will shape the garment or pieces first and then wet them. Stretch your items out and pin them to the correct dimensions on a blocking board or other colorfast, absorbent surface. (You can use several towels layered over one another to create an appropriate blocking surface.) Once the sweater is secured in the shape that you want, use a spray bottle to evenly dampen the surface and allow to dry completely before you remove the pins. If you don’t have a spray bottle, you may also lay damp cloths or towels on the sweater to achieve the same results.
To steam block a garment, you will prepare it just as you would for spray blocking above. After the item is pinned into place, pass an iron (on the steam setting) or a steamer over the fabric, holding it about an inch above the knitting itself. You don’t want to touch the steamer or iron directly to the fabric because it could flatten the stitches or create an undesirable sheen. If you are worried about touching the knitting with the steamer, you can place a thin towel or sheet between the heat and the sweater.