I pulled out a jar of Cold River sandalwood a couple of weeks ago that I hadn't shaved with since last year when I moved from Orange County to the Bay Area here in Cali. It went from being a 'Great Soap' to being 'Hands down best lather I've ever produced', and I was curious if it was my technique improving over time or perhaps the water. Well, my wife & I went down to OC last weekend to celebrate our anniversary & I brought along my Cold River and sure enough it was 'great' versus 'best ever'. So apparently there's something about the water up here that magically unleashes the full potential of Cold River goodness. Any other examples you all have of a soap that dramatically changes its properties from one location to another? This is the first time I've noted such a 'Tale of Two Cities' phenomenon.
Should be able to conquer the issue by using more product. First the soap has to clean the minerals out of the water, then it can make lather. For a controlled experiment try distilled water.