Hi Mike,
Thanks for your continued support and honest review. We still need to get Stephane to do a comparison video for us although whatever he finds will not change what any given invidual experiences with this product line. When we had a major manufacturer-based backorder of our regular 600 grit, several customers ended up picking up the new Blue paper in isolation (without trying any of the other grits) and had similar concerns... and so we investigated:
Stephane evaluated most of the major grits of this paper before we took it on (up to and including 600), and after your (and others') thoughts he has tried 2-3 different batch codes of the 600 but found he wasn't personally able to recreate the issue in our shop. He found he was able to go from 320 in both the Blue and our original sandpaper to the 600 and uses about the same number of discs in both cases (although he found he got substantially faster cut and longer life from the more coarse grits in the Blue paper). We also recently sent some of our original discs to the new manufacturer to check whether they felt the grit was slightly different (e.g., if their 600 felt like our 800) or if the openness of the coating varied, but they agreed that the Blue discs were if anything more coarse/aggressive than our original Spectrum discs. The main difference they found was that the anti-loading agent used in the Blue discs is built into the resin whereas on our original discs there is a double layer of sterate anti-loading agent applied on top. My assumption is that - particularly on the finer grits, where the abrasive grain and resin are both shorter - the resin-based anti-loading is available, by definition, in reduced volumes compared to the coarse grits. Our thought is that this could lead to more visible glazing with the Blue paper in the especially fine grits (especially since finer grits tend to load more readily as-is).
We hope you'll consider trying other grits in the line before you make your final judgement (the performance is well worth the small extra expense). And while it's possible the challenges you experienced with the 600 grit Blue discs could be mitigated by use of a sanding grease or ebrasive cleaning 'eraser', we recognize that our customers expect a product to stand on its own - so as you'd expect, our original discs will remain available going forward!
