I have a Tapestry application, that retrieves data from a form, writes it to a database and then displays the result. It all works well as long as no special characters (Ä,
I have tried your test string in Tapestry 5.2.6 and 5.3.0-SNAPSHOT and it worked fine. I was able to persist it to the HSQLDB database and pull it back out as expected.
What version are you using? If you are back in 5.0.x you may need to do something like this: http://wiki.apache.org/tapestry/Tapestry5Utf8Encoding