A friend of ours used to own a chocolate factory, and she would get blanched hazelnuts in big boxes. These were only lightly toasted, if at all, but they were perfectly cleaned - not a single recalcitrant paper skin in the bunch.
I've used both the roast & rub method and the baking-soda method (boil water with a couple tablespoons of baking soda, dump in the nuts and boil for a minute or so, rinse & rub) for blanching hazelnuts. While the latter is vastly preferable, it's hard to get the timing & baking soda quantity exactly right, so either you end up with perfectly clean nuts that are a little cooked (not to mention dyed) looking, or you get nuts that are only mostly clean. So whatever the big suppliers do, it doesn't seem to be either of these methods.
Does anybody have actual experience with blanching hazelnuts on a large scale? What method do they use to get those perfect results?
(Failing that, I'll accept pointers on the baking soda method, i.e. how do I tread that line between dye-bath and ineffective?)