Arrayjet microarray printers are compatible with the JetGuard, a self-sealing silicon mat well septa which creates a microclimate with 100% relative humidity around the sample. In-house experiments have demonstrated that within the first hour, aqueous solutions can lose over 10% of their volume from unprotected 384-well plates; Arrayjet’s JetGuard effectively eradicates this source of variability. Arrayjet is the only microarray technology to use these septa, through which the JetSpyder can penetrate and access samples. The JetGuard is also successful in protecting samples from external contamination.