In cloudier conditions on the second morning, Glamorgan’s bowlers limited the damage already caused on day one, despite ironic applause when the extras tally passed 50.
Van der Gugten (2-67) dismissed nightwatchman Matt Taylor and fizzed one through the defences of Miles Hammond, who had reached an attractive half-century.
Gloucestershire reached four batting points with ease but gifted Glamorgan a second bowling point with the last ball of the 110 overs, when James Bracey was run out for 25 after a poor call by van Buuren.
Chris Dent played a bright cameo of 27 before being caught behind off Ned Leonard, before Ul Hassan (2-66) won a generous lbw decision against Tom Price (21) to break his own wicket drought and then had Zaman Akhter caught at slip for 15.
Van Buuren was last out for 48 swinging at Shoaib Bashir after a flurry of big shots, but that still left Glamorgan with a marathon task to save the game.
Ul Hassan got them off to a bright start with six boundaries in his 28 before Tom Price found the edge, while pacy change bowlers Ajeet Singh Dale and Zaman Akhter caused early problems.
But it was Matt Taylor who returned to have Eddie Byrom caught behind for 28, although Northeast drove fluently with nine fours on the way to a relatively untroubled half-century.
But Singh Dale found extra pace in the evening gloom to induce Northeast to fence to rival captain Cameron Bancroft at slip.
Kiran Carlson got through a jumpy start to battle alongside Colin Ingram until the heavy cloud cover frustrated the home side and brought the first weather interruption of the county season.
