If you've ever knitted a sweater in superwash yarn, finished binding off and smiled because it looks so awesome, then blocked and thought WHAT????? ..... this post is for you.
The process of making wool yarn washable, strips its natural elasticity. A merino superwash wool, which is already soft, can become a huge (HUGE) mess of wet fabric as you take it out of the sink. It just doesn't spring back and behave as nicely as pure wool or untreated yarns. But don't let this shy you away from knitting sweaters with superwash yarns. They can feel so wonderful with a few extra steps. But before we get into the blocking stage, make sure you have knitted the right size.
Before casting on, knit a generous swatch in the stitch pattern used in the pattern. Aim to knit a minimum of 4x4"/10x10cm swatch or even better is a 6x6"/15x15cm swatch. Write down the pre-blocked stitch and row gauge. This lets you know as you're knitting, if you're on track with your gauge. Wet block the swatch and let it dry flat naturally. If you pin the swatch to keep the edges from curling, be careful not to stretch the fabric out. Shake it out when it's wet and let it fall on the blocking mat. Once dry, remove the pins, shake it out, and take your gauge again. Write down your blocked stitch and row gauge. This is what needs to match the gauge written in the pattern.
When knitting, if the pattern says to "continue until piece measures ...."/cm,", if your swatch row gauge was different after blocking, you'll want to measure the length by counting rows and comparing them to your blocked swatch, instead of measuring the fabric. Here's a good video on measuring sleeve lengths when knitting with superwash yarns.
Now that you're confident that you've knitted the right size, it's time to block this superwash sweater.
First, before running the water, pull out your blocking mats, pins and have the schematic handy. Place pins on blocking mat for each measurement based on the schematic, before adding garment. This gives you an outline. Using the schematic measurements as a guide, work with your tape measure and pins, and place one pin on each end of the bottom edge to mark the front/back width, one at each armhole to mark the body length, one at each end of the cuffs to mark both the cuff width and sleeve length, one at each edge of the neck and so on. You don't need many pins at this stage. You're just trying to create an outline of the size of the garment.
Next, fill a sink with tepid water and swish around a few drops of a mild detergent like Eucalan with lanolin. Lay the sweater on top of the water. As it soaks, air bubbles will surface, and the sweater will sink to the bottom. It's normal for some dye to be released especially with hand-dyed yarns. Normally superwash sweaters take less time to absorb water than pure, non-treated wool, and it may only take a minute or two before the fibers are saturated with water. If working with hand-dyed yarns, don't let them soak longer than needed.
Once the garment sinks to the bottom, drain the water. Press the garment gently into the sides of the sink to remove excess water. Don't wring out. Wool, alpaca and cashmere are weak when wet so be careful not to pick up the garment while it’s wet as you can stretch the fibers out of shape and damage it. Ease the water out of the garment by pressing. When most of the water is removed, lay a towel over the sweater in the sink, and fold the towel around your wet blob of a sweater. Press again to absorb extra water. Replace the towel with a dry towel and gently lift it, while supporting all the weight underneath, onto another towel. Roll and press out more water.
Gently carry your bundle to the blocking mats and place in the center of your outline. Remove the towel. Start by gently arranging the sweater inside of the outline of your pins.
NOTE - it will be too big! Don't worry. At this stage (the OMG stage) you will be convinced that the sweater is ruined and can never be worn. This is the stage where most problems happen. If you lay the sweater out to the shape it wants to be now, it will be huge, it will dry huge, and it will never fit.
But if you lay the sweater out within your outline of pins, then pin the garment to the mats using the pins already in place, you will notice folds and gathers, but it will eventually draw in.
Add extra pins as needed to keep edges straight. Leave it lumpy, without smoothing it out. It will draw up as it dries. If a garment is long, heavy or the fabric has a lot of drape, pin the length (body and sleeve) about 1"/2.5cm shorter than listed in the schematic to account for the downward pull after blocking. You want it to have room to hang once worn.
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Turn a ceiling fan if you have one. Leave it alone for at least a day. Come back and remove a couple of pins if needed to slide your hand under the fabric and fluff it up a little. This prevents wrinkles from forming and gives the fabric room to re-adjust to the size as it dries. Do this a few more times as it dries. Once the front is dry, carefully flip it over, keeping the outline intact, and let the back dry. Do not stretch it out.
Once dry, it should have drawn up to the correct measurements in the schematic, and fit! Once it's dry, it you still need it to be a little smaller, or if you just want to remove the wrinkles, you can place the sweater in the dryer on delicate/low heat for a minute or two. Stand by the dryer and keep opening the door to check it. Don't do this while it is wet because the tossing action will cause it to stretch out of shape. There seems to be a magical minute between nothing happening, and smaller! so monitor this carefully.
I hope you will continue to knit sweaters with superwash yarns, following these swatch and blocking tips. They can be some of your favorite sweaters!