Wow, good analysis Cavimum. For one thing, I had expected the blanket to appear extra-puffy because I'd assumed the dry cleaning chemicals would somehow raise the loft and nap. But, actually, it seemed, if anything, thinner than it did going into the process! Maybe they had to press it to get wrinkles out?

But I also now wonder if some of it is psychological. For the 2.5 weeks of it being dry cleaned* I was using an old electric blanket...that I hadn't used since buying the wool one. I was not using it plugged in...just as a plain blanket. But it is 100% synthetic with, probably, an impermeable insulator layer sandwiched in the middle. It doesn't breathe well and didn't seem comfortable at first, but it was probably a very warm blanket. So switching back, maybe old woolie just felt cooler.

* -I live in a rural area so it's a long drive to what was a dry cleaner with many good yelp etc. reviews. There was a weekend or two I didn't have time to make the trip.

I work with fibers and have about a dozen wool blankets, some I bought new and some are vintage. I think my favorites are some of the merino faribault blankets. I never dry clean mine as I think that it is hard on the wool. You do have to dry clean structured things like suits or pants but I wash blankets and sweaters.

The lanolin is gone from commercially processed wool. Maybe they put some other finish on it. Sheep are filthy animals and they use some pretty strong chemicals to dissolve all the muck. If you can find wool processed by an individual you might get some lanolin left in. There are ways to relanolize wool but the main benefit of that is water proofing as Cavimum says rather than making it warmer. Some people do it to diaper covers.

The sheep fiber has a structure with scales called the cuticle. This is kind of an interesting picture of different fibers.

If you wash wool in hot water and agitate it like crazy, the cuticle opens and and the fibers get entangled and shrink up. This is great insulation but of course you don't want that for your blanket.

When you wash it in cool water though with the bare minimum of agitation and just a small amount of something to help any dirt be carried away, you get just sort of a restoration to the cuticle which helps with the loft. I use my top load machine but it has a handwash cycle and I know what it will do. I use a very bland shampoo or if really dirty, I might use a detergent without enzymes. You have to read the package to make sure there are none each time you buy. You could handwash pressing the water through the blanket, in a sink too if you are worried about your machine being too much. I rinse several times. If you have a top load machine, you could spin it out if you lay it carefully in and avoid it pulling anywhere when it spins. If you can't do that maybe lay it on towels. I usually add just a tiny bit of hair condition to the second to last rinse which helps in blocking if you want to do that. I usually dry blankets after they spin out on one of the beds.

The cleaners might have put it into a press of some type and thus flattening it. You could call and inquire. I have a wool throw and I wash it in our machine; it has a Wool cycle, then dry on very low heat in our dryer that has a Woolens setting. It comes out a bit fluffy and I don't press out the wrinkles.

I use Perwoll detergent for woolens (I love the cedar-like scent) but you can use baby shampoo, which is cheaper and easier to find. The shampoo pH is right for wool because, like human hair, it is a protein fiber and not quite as alkaline. Regular laundry detergents are more alkaline. They won't kill the wool but they won't do it any favors, either.

Orvus Paste is livestock shampoo and will work fine, because of the pH factor, if you can get a small jar at a quilt shop, or on Amazon. One tablespoon is enough in a TL washer, less if it's a FL. Trust me, a little goes a long way. When I bathe the dog with Orvus, the fur is very soft and shiny. Our local farmers co-op has it in big jugs that last forever. It is nice for silk, too, for the same reason. And no scent or optical brighteners. Orvus is very sudsy, though, so once we got a FL washer I stopped using it.

I always wash my wool with a detergent for wool (like The Laundress Wool and Cashmere shampoo) and most of it comes out better - soft and fluffy. I had one cashmere throw that seemed to "felt" which is no good.

https://www.thelaundress.com/clean-talk-blog/how-to-wash-wool-cashmere.html

If you have a small amount of shrinking you can use a little hair condition and then rinse a couple of times and you might be able to block it. I have washed a lot of cashmere.

I wondered if it was the quality of the cashmere. I washed several other cashmere items that didnt felt like this throw did.