This is a list of my current rules of thumb on washing various knit fabrics
- Softly, lofty yarns, (not spun from super wash) with few plies knit at typical modern gauges ( http://www.craftyarncouncil.com/weight.html ) tend not to survive a trip through the washing machine (Cotton cycle) and dryer. Such objects, that are fulled from long and gentile use may survive, but by then it is a treasured object, that should not be treated so roughly. Mostly, I would say such objects should be placed in a net bag, and run through the "wool" cycle and then blocked to dry at room temperature.
- Objects knit from worsted spun yarns, with fine plies (e.g., gansey yarn) knit moderately firmly to firmly (sport weight on 2.5 mm needles) will tolerate passage through the washing machine and dryer. Here, I am talking about washing with a 38 minute cotton cycle at 140 F with Percil (a good EU detergent). This will remove even oxidized and recalcitrant lanolin.
- Semi-worsted yarns knit firmly ( e.g., worsted weight yarns knit on US #1 needled) are improved by a passage through the washing machine and dryer as it fulls the fabric leaving it soft, dense, and slightly napped. My standard test objects were knit from MacAuslands fine 2-ply Naturals ( 2-ply, 880 ypp) on US#1 gansey needles. (I was rather appalled at how much dirt my hand washing or even the wool cycle had been leaving in the objects.)
- I assert that for some fabrics, a trip through the washer is the easiest way to get the fabric really clean, and that worsted spun yarns, knit firmly, can tolerate this on a regular, if not frequent basis.
- The washing machine rinse cycle can be used to apply 2 drops (1/8 teaspoon) of baby oil for wools that must tolerate some moisture. I do not have any problem putting such oiled wools in the dryer.
- Wool objects that must be weatherproof need re-oiling with real lanolin. (Put the object in a large pot of water, add a good teaspoon of solid lanolin, and warm until the lanolin melts. Pull/ drop the object through the film of melted lanolin on top of the water several times, so the lanolin can adhere to all parts of the object.) I do not put such oiled objects in the dryer. Oiled objects tend to collect dirt and yellow. And, lanolin tends to attract wool eating bugs. I put several drops of lavender oil in the oiling pot, I do not know if it keeps bugs away, but it does not seem to hurt.
- I suggest taking wool objects out of the dryer at the "damp dry" or "machine iron" level of dampness and blocking.
If you are thinking about such aggressive washing, try it on swatches first. I really do knit much tighter than most modern knitters believe is possible, and this produces a fabric that is more durable than most modern wool fabrics.
Slightly higher grist yarns knit on the same needles or slightly softer yarns, or yarns knit slightly softer (e.g., larger needles) WILL felt and shrink. I knit soft turtle necks on to some of my fishing sweaters. The body of the sweater does fine, the turtle necks shrink to fit fruit flies. Swatch and test all trim.
While I do believe that "better spinning is the comparative advantage in textiles" ,