I used to use silk thread for embroidering on church linens, but the people who do the church laundry use God-knows-what to clean them and they are laundered, starched and ironed after every use. The silk just disintegrated - probably due to bleach, but OxyClean can do that, too.
I agree with SherylM - it would be a waste of silk to hide it and run the risk of ruining your piecing when someone runs it through the washer with some cleaner that isn't kind to silk.