Disclosed are formulations of gamma-hydroxybutyrate in an aqueous medium that are resistant to microbial growth. A plurality of rubbing rolls can be rotated, and by keeping the plurality of rubbing rolls in storage in the closed roll stocker, contamination of a rubbing cloth due to external particles can be prevented, space utilization can be enhanced, and deviation of eccentricity of the rubbing rolls kept in storage can be prevented. On the lower edge of the plates there are a conveyor means for insulating glass and a channel for the supply of heavy gas into the space between the plates and into the interior of the insulating glass sheets. The head portion further includes one or more rollers coupled thereto in a position spaced away from an interior surface of the backing plane, and a retention tongue between the one or more rollers and the interior surface of the backing plane and being set back from a circumference of the one or more rollers.