An apparatus and method for replacing air with an insulating gas during manufacture of an insulated glass article having two parallel panes and a peripheral spacer between the panes. The apparatus includes an upright first platen, a second platen confronting the first platen, a mechanism for moving at least one of the platens toward and away from the other platen, and a peripheral resilient seal positioned to define a sealed enclosure between the platens. The apparatus may further include a conveyer for conveying a partially assembled insulating glass article between the platens, an exhaust mechanism for drawing gas from the enclosure, and an intake mechanism for introducing insulating gas to the enclosure. One method of the invention involves filling such an insulated glass article and measuring the thickness of the article to detect bulging or cupping.