Hi threedogs,
Typically wool batting will compress by about 30% of its thickness but it will also depend on the species of wool used and the design and construction of the topper. While it will become firmer when it’s compressed it still has resilience because of the curliness of the wool fibers and it doesn’t pack down and get as firm as cotton batting. It can also be shaken out and put in the sun for “self cleansing” which can help it recover some of its loft.
I’ll be very interested in your comments about your DIY buckwheat hull mattress both with and without the topper. I’ve slept on a buckwheat hull pillow but not a mattress. You can see some of OYEB’s comments about them in posts #5 and #7 here and it would be great to have some additional feedback.
Phoenix