The mid-infrared properties of gamma-ray emitting blazars have emerged as a distinctive features of such sources that rival with other more classical features of blazars. The gamma-ray emitting blazars occupy a narrow and peculiar region of the WISE color space, the so called WISE blazars locus. Such unique pattern has been shown to be effective as a tool to associate unidentified Fermi sources to candidate blazars extracted from the WISE photometric catalog. In this talk I will discuss another use of the blazars locus, namely the extraction of a list of candidate blazars from the WISE all-sky photometric catalog.
I will discuss the new modelization of the locus that employs three different regions, respectively dominated by BL Lacs, FSRQs and mixed, in the Principal Component space generated by the WISE mid-infrared colors space of a sample of confirmed gamma-ray emitting blazars. This new extraction method is also capable of taking into account the local contamination to the WISE locus from non-blazars in the WISE catalog, and can be fine-tuned to achieve distinct efficiency/completeness trade-offs. FInally, I will discuss the application of this method to the All-Sky WISE catalog and will give some details about the statistical properties of the catalog of candidate blazars extracted.