Sensing in e-textiles has generated great interest in a wide range of applications, including wetness detection. A common application for wetness detection sensors is the detection of urine in absorbent products such as diapers. However, unlike water, salinized liquids like urine accelerate the process of chemical reaction of integrated conductors (especially when exposed to electrical current), limiting the lifespan of e-textile sensors. This paper explores an approach to extending the lifespan of conductive thread sensors by blending copper filament with silver threads, and a comparative bench test of the effect of adding copper on the functional lifespan of a wetness sensor when exposed to saline. We find that while the bi-metallic sensor is effective in lengthening the lifespan of the conductive traces, it is likely due to the increased metal content rather than selective reaction of one metal to preserve the other. We make suggestions for further optimizing sensors.