Yes the answer is, there is no information at all about Dolhain Wirths. I have quite a collection of Dolhain souvenir pieces, from as far afield as Whitley bay, Switzerland, Belgium, France and Holland. As far as I have been able to grasp the company was a decorator, not a glass maker because they never featured in any of the trade journals. They must have been located in Dolhain, a smal village on the Belgian side of the border near Maastricht. The company name was Wirths. I suspect their blanks were supplied by Val St. Lambert - but they may have imported them from Schneider or Legras too... It is uncertain when they worked but it seems likely they were active at least until the thirties - but as said, no written record has been found in any publication so far. Do let me know if you find out, will you?