Part of a series that begins with Blocking Notes (Intro).
Blocking Prior to Seaming
There are conflicting opinions about weaving in tails prior to or after blocking. In theory it's a good idea to weave in the yarn tails that won't be used for seaming prior to blocking, as the blocking process will help them settle in and be less visible, and this is the method recommended in [STAN, p 224]. If, however, you need to stretch the article a lot during blocking, don't weave in the yarn tails as the yarn tails may pucker [HOLL].
For blocking an item prior to seaming, I like to use wet blocking, although any of the methods can work.
Shape the pieces according to the schematic. Every part of the garment that will be seamed needs to be measured carefully to make sure the pieces match. You may need to use a lot of pins to make the edges as flat as possible so that seaming the pieces is easier. It's also possible to steam press the edges of the pieces to make seaming easier, touching the iron to the knitted fabric through a pressing cloth. I've tried this method. I find it tends to flatten the edges so I don't recommend it unless it's a dark yarn that's difficult to seam otherwise. I'd recommend testing on a swatch first, then washing the swatch again to make sure the fibres bounce back from this treatment.
Let the pieces dry completely before unpinning them from the blocking surface.
Blocking After Washing
Blocking after washing is reasonably easy for garments. Press them gently into shape (check the measurements against the schematic of the garment) on a towel or drying rack, and let them dry (you may need to change the towels a couple of times). Some yarns are marked machine dryable and you don't need to block these after washing.
If the article is a lace shawl or tablecloth, then you'll probably have to go through the whole blocking procedure with the pins or dressing wires again. Some yarns do have a “memory” of being blocked and remember the shape somewhat, but whether this is sufficient depends on the pattern, the yarn, and how strongly it was blocked the first time around.