Hi Adam,
There used to be a page on the Riihimäki Glass Museum site with a brief history of Humppila and Kumela. Unfortunately, it's been deleted. However, a bit I've gathered together about Humppila (from this and a few other sources).
[*]Founded 1952 by Jonni, Martti(??) and Olavi Helander, brothers who had previously worked at Nuutajärvi as glassblowers. The works produced both 'art glass' and household wares. You occasionally see items signed 'Helander'. At this time some of the 'art glass' produced was Gunnel Nyman type controlled bubble items - I believe Helander brothers had made the originals when at Nuutajärvi.
[*]Sold in a forced auction 1970 (there had been financial problems). New owner Rolf Alander.
[*]1976 Humppila buys the Kumela glassworks from the Kumela family (Blomqvist had designed for Kumela). Kumela continued to produce glass by blowing and lead crystal, while the Humppila works concentrated on centrifugal casting and more mechanical means of production.
[*]1986 Sold to Wärtsilä, owners of Nuutäjarvi. Subsequently, though the various takeovers/mergers, part of Iittala Oy Ab. Factory still exists, as part of Iittala.
There is also this site with some info on Blomqvist/Humppila, including other Humppila designers http://koti.mbnet.fi/jost/lasi.htm. If you find out anything else, I'd be interested to know.
robbo