Would it not also shrink, making the item irregular in shape? Have you used wooly nylon? It was recommended to me at a serger class.

No, I haven't, but I will be checking back here as I am interested in the answer.;)

I have digitised for woolen thread. It needs a lower density and larger stitchlength. I would not use an 'normal' design that would give a lot of problems when stitching, nor would I recommend letting it felt as it would shrink in the process and distort the fabric.

I bought lots of colour Madeira wool a few years ago full of enthousiasm as I have some designs for it, but it is quite thick and though designs were digitised for it I found it difficult to work with, as you will also need a much larger hole in the needle etc. I must try again some day as I have all those reels lol.I would recommend to anyone wanting to try just buy one reel first.
Do also feel that it will not work at all on soap, I had animals in mind when I bought it all.

Try in Bobbin, You tube probably have a tutorial..

I am sure wooly nylon is what I use in my overlocker

In poking around Embroidery Library, I came across this tutorial for thick thread by Kenny, using Burmilana or Lana size 12, combo wool & poly or nylon, I forget. Kenny says use ONLY on designs digitized for thick thread. Embroidery Library has certain designs labeled "thick thread", you can search for them. I'm adding the link to the information. The photo looks really nice, more like crewelwork. Have a good time, hugs, Marji

Good post very interesting.
I have used two threads befor and that is ok on the thickness side of things.
Hugs Pam.