Why is it so soothing to scratch satin edge of my blanket at 57 years

Am an incest survivor. Been in recovery off and on for 25 years. Had complete amnesia about childhood until age 29. Sucked my thumb until high school. Did not scratch blanket since I was a young child. Only recently I started when my sister gave me a blanket to comfort me. I have severe arthritis and was going to have double knee replacement surgery and was scared and anxious about it. Did not have new abuse memories until a few years ago. I have been praying for any past memories that are holding me back from having the I want. I asked and have been getting new memories. Scratching the satin edge is so soothing. Rubbing it does not do it for me, Only scratching. Helps me fall asleep. Read that toddlers are to attach to an object so they can comfort themselves when mother is not around. I just assume the abuse started when I was a baby or toddler. So my baby blanket had extra comfort for me. Why it is only scratching is so interesting. Most people like soft things especially around their face. Any ideas why scratching is soothing?