Aging and compositional effects of silicalite layer synthesis on a quartz surface using the vapor phase transport method were studied. Silicalite layers can be synthesized from a wide compositional range when not-aged mixtures were used. But reproducibility of the film synthesis was low due to the heterogeneity of the starting mixtures. In order to increase the reproducibility, both aging of starting mixtures and compositional changes were attempted. Silicalite layer can be synthesized successfully on quartz surface within 0.3 of the ratio TPAOH/SiO₂. Higher ratio of TPAOH/SiO₂ smaller crystals are formed. If the TPAOH/SiO₂ ratio is larger than 0.3, the formed silicalite crystal cannot be attached on the quartz surface. When the TPAOH/SiO₂ ratio of the aged starting mixture was 0.28, requirements for both reproducibility and smaller crystal size resulted were satisfied. The crystal size and shape in the silicalite layer are also influenced by the water content in the mixture. The crystal size in the silicalite layer increases with increasing water content in the mixture.