Warm water, tepid, not hot, not cold . Gentle wool detergent or hair shampoo. Stretch a bit in water (bath) then lay out flat wet. Do not wring. On towel.
Pull to stretch. Dry slowly over a day or more. Flat on towel. No hot heat
yup. temperature, agitation, alkalinity of detergent can all result in the shrinkage. Even agitating by hand too vigorously ion cold water can result in some shrinkage. When you knit wool fabric it undergoes fulling to close up the fabric and make it more dense but softer. It is done by agitating the wool. That's what the shrinking really is. There is always more shrinkage left in it depending on what caused the original shrinkage and how much. looser knits more.
that makes sense, I have had a couple of jumpers shrink very slightly by washing them in cold water by hand. Too much agitation.
Some cashmere jumpers are impossible to shrink. I used hot water on a 6 ply Ballantyne and left it out in the summer sun and repeated this process 4 times and it got bigger. No problems, l send it to perhaps the world's top knitting expert and she is unraveling it and reknitting it in the exact pattern/6ply style. She has shortened it, took it in slightly at the sides and shortened the sleeves and added a loop at the top. It will be worth the wait and all the work done on it imo. She works with the top knitwear and has done this type of work successfully before.
btw, those Berk/Ballantyne 3 ply turtlenecks I bought recently are utterly fabulous!!! Beefy and great quality. The Ballantyne 4 ply's l also bought are amazing....one is an 80's 4 ply intarsia, so rare.
I put the pullover in a basin with cold to mild water. I left it there for one hours or so. Still wet, I stretched the sleeves and the body with care but with force. Afterwords I left it over a towel until dry.