I found this piano on craigslist and was wondering if anyone could shed some light on the issue of unmarked pianos. Why would a piano have no manufacturer's name or serial number? I have seen/played the instrument and it isn't terrible, but I definitely don't think it is a Mason and Hamlin...

http://grandrapids.craigslist.org/msg/3065272746.html

Greetings,
The reason there is no markings is that it is probably a "stencil" piano. During the early 20th century, there were dozens of piano builders that made generic instruments that were sold to stores. The stores would have their own decals made up, and stencil their names on the piano. Few of these instruments were built with sufficient quality to still be viable candidates today.
Regards,