A seal device for a developer system in an electrophotographic printing machine, including: a developer housing containing toner particles; a donor member rotatably mounted in the housing for transferring toner particles to a latent image on a photoreceptive member moving in a process direction; a toner emission system for collecting toner particles with a vacuum; and a seal member, mounted to each end of the housing and in contact with the photoreceptive member, to retain side ways migrating toner particles from escaping each end of the housing thereby substantially reducing toner particles from being emitted past the housing.