I have washed old tops knowing it was my only option because they were so filthy. I folded the top and put it in my kitchen sink with tepid water, dawn dish soap and baking soda. I let it soak for an hour then gently pushed my hands down numerous times on the still folded top. I drained the water and ran cold rinse water two times, gently pushung down on the top. Leaving the top folded I blotted the excess water. Then unfolded and hung it over the shower bar in my bathroom, gently arranging it to hang flat. This worked for me. Some fo the grime didn't come out but it was clean enough to quilt. After quilting and binding it I washed it in the washing machine on gentle and it came out good and clean. Good luck, it's always chancy when you wash a top that someone else made years ago.