I am often asked how I prepare my wool for sewing. Many people will tell you to dry clean, London shrink (roll your damp fabric in between two sheets and allow it to dry naturally over time) or steam press (press the entire piece with a ton of steam) the length of wool before using it. Any of these methods will work wonderfully. However, I really don't like dry cleaning - the smell is yucky and I'd rather spend the money on more fabric. Although less toxic and less expensive, London shrinking and steam pressing a whole length of fabric is my version of torture - I just don't have the patience for them. So, I opt for another method - the quick and lazy method. I use this technique on every single piece of wool or wool blend fabric that comes into my home. I have used this method successfully with every weight and weave of wool - crepe, gabardine, jersey knit, boucle, gauze, tweed, melton, etc.
1. Fill washer with cold water and add a dollop of Eucalan and agitate briefly.
2. Add the length of wool and fully submerse.
3. Allow wool to soak for 20 minutes.
4. Spin out water.
5. Hang wool to dry over shower rod or place in dryer on gentle cycle.
The choice of hanging on a rod or placing the wool in the dryer depends on the type of wool. If I am concerned that the wool may undergo the process of fulling, I hang the piece to dry - for instance this can be a problem with crepe. If the wool is a tight weave, like gabardine, then fulling is usually not a problem and into the dryer it goes.
Sometimes, I do want the fabric to thicken up a bit and undergo some degree of fulling. Then, the wool is washed in hot water, on the regular cycle in my machine, with laundry detergent added. The rinse cycle is cold water. The washed piece then goes into a hot dryer. Depending on what I want the final product to look and feel like, I may repeat this process several times. When I do this, I typically start out by laundering a 6" x 6" swatch, to see how much it shrinks and what happens to the texture, just to be sure that I like it before proceeding with the whole length of fabric.
After the initial pre-treatment of the fabric, the wool is ready to sew. Once I have created the garment, I always treat it more gently than what the fabric endured during pre-treatment - this ensures that no further shrinkage will occur. All wool garments are soaked in cold water with Eucalan, spun out and hung to dry. When slightly damp, I touch up any wrinkles with a warm, dry iron.
Now, of course I have to put in a disclaimer. If you have any concerns about a method for prepping wool, test the method on a swatch first. This way, if something does go wrong, you haven't ruined the whole length of fabric.
ETA: Lisette asked, "I really like your method for preshrinking...but I am concerned about lined garments. Do you also put these in the washer?"
I always wash and dry all my linings (Bemberg rayon, silk charmeuse, china silk) and underlinings (silk organza, cotton batiste, cotton broadcloth) if they have the possibility of shrinking. I preshrink all my interfacings (I use both sew in and fusible) by soaking in water and hanging to dry. This allows finished garments to be soaked briefly in cold water with Eucalan, spun out and hung up (or laid flat if I'm worried about distortion) to dry.
Now, I don't wash my tailored garments (the ones with lining and interfacings) too often. For the most part, a tailored wool jacket will only see water every six months to a year, unless I have spilled something on it, for two reasons. First, I have a fair number of clothes, so I don't wear any one piece over and over in any given month. Second, most of my wool garments just need to be freshened up with a short trip through the dryer. I put the garment in the dryer with a damp face towel for 15 minutes - the damp towel provides a bit of steam to freshen the garment and loosen any wearing wrinkles. I am not worried about sweat because I keep my room cool at school in the winter and I usually wear a jacket over a blouse or T-shirt and skirts are worn over slips and hosiery.
As for my non-tailored stuff, it gets laundered all the time. I have a Silhouette Quilted Jacket made of wool boucle that is soaked in cold water with Eucalan and laid flat to dry on a biweekly bias. I have been treating this garment like this for over two years now and it looks just as good as when I made it.
Once again, if you have any concerns about doing this yourself, err on the side of caution. You don't want to ruin a garment you have put a lot of work into - maybe you could first try this method on a garment that you are thinking of purging from your closet or you could create a mock up with pretreated swatches - take a piece of wool, fuse some interfacing to it and sew on some lining. I tend to be fairly ruthless with my stuff - if I have to baby it, I will grow weary of the babying PDQ and get rid of the garment anyhow.