Over time we have begun to build foundations for design ontology moving it away from efforts to align with a scientific rigour model based on reproducibility and generalisability towards a new direction supporting design’s emergent and abductive qualities. Two of the key issues that have escaped our grasp has been a better understanding of design ontology and what equates to rigour in constructive design research. Recent work by the authors has positioned transferability as a candidate for a design ontology based on an ontological mirror along with a series of attributes addressing the rigour issues of future-forwards knowledge generation. Here we use two case studies to test the future forwards rigour of a transferability property for design knowing and speculate as to how researchers can build confidence and trust.