The New Liturgical Movement has an excellent post on Reclaiming the Sacristy as a Place of Prayer and Preparation I am glad to say that we already follow several of the suggestions in my sacristy. There has to be some talking with the sacristans and servers in preparation for Mass but it is understood that when I begin vesting, the servers line up and there is silence while I say the vesting prayers and the prayer of intention before offering Mass.
I remember the Silentium sign in the sacristy of St Mary's in West Croydon when I was a small boy but I have not yet put one up in my sacristy. I'll have to look for some nice parchment to print it on and then frame it.
Here is an inscription that I photographed in a Church some years ago when I was visiting Granada.
The inscription reads:
Vestibus hic sacris locus est
exuvias hominis veteres
atq(e) indue Christum
This is the place for sacred vestments. Put off the old coverings of the man, priest, and put on Christ.