Docs, usually how long is shingles contagious on a solid surface?

Blisters key: Shingles is contagious to people who have not previously had chickenpox, (they get chicken pox) as long as there are new blisters forming and old blisters healing. Similar to chickenpox, the time prior to healing or crusting of the blisters is the contagious stage of shingles. Once all of the blisters are crusted over, the virus can no longer be spread and the contagious period is over.

See below : Only until blisters crust over.