Thread: Lapping a Norton

I just received my new Norton 4/8K water stone and want to lap it first before honing using the sandpaper method. A few Questions: Should the lapping procedure be done with the stone wet or dry? If wet, how much wet? After lapping should I just wipe it off with a cloth or wash it off? Thanks.

I personally don't use that method but you have to use wet sandpaper, very wet and afterwards you need to wash off the stone preferably with a scotchbrite pad and plenty of water to make sure you remove all the particales otherwise they will do a number on your straights.

And when your lapping be sure to use a X or Figure 8 pattern.
Use a high quailty sandpaper like 3M or McGuires. Go up 600 grit at least.
Before you start lapping draw some lines on the hone with a pencil. Lap until the lines are gone. Then the stone is flat.

In my experience you need to keep lapping a little more after the lines are gone, as the hone starts getting flat it starts developing more suction going over the watery sandpaper, and starts sucking the sandpaper up off the plate a bit as it goes by which sands the lines off before it's really flat. It could also be the slurry sucking up and swirling around doing this, but if you do another few laps after the lines disappear you'll be happier.

Thanks for the info. Apparently wetting the sandpaper is a necessary step, but what about the stone? Should the stone be soaked for 10 minutes before lapping? Also, what do you think of using silicon carbide sandpaper instead of 3M wet/dry paper? Which is better to use and why? Thanks.

I soaked my stone before lapping. If you don't the stone will soak up all the water and swarf; a dry norton is a sponge with an abrasive personality. The point of the wet/dry sandpaper is it will hold up to the drenched beating, dry sandpaper will promptly drop the grit.

Absolutely soak the stone prior to lapping. As far as silicon carbide vs. wet or dry paper, they're the same. The wet or dry sandpapers typically are silicon carbide. The brand usually indicates the quality, though. 3M and Norton papers (not familiar with the McGuire's, Randy) typically have a better resin bond than the cheapie papers. Translation: you get less grit contamination off the good, quality papers than the generic brands. And usually the price difference isn't that much.

OK, you guys answered all my questions, but I have one more. I've been told to use 400 grit paper on the 4K side and 800 grit paper on the 8K side. I've also read of some people using 1000 grit paper on both sides. What is the absolute best grit to use on each side of the Norton? Thanks.

The directions that come with your norton should give the "official" recommendations, which work quite well. As I recall it's something like 320 for the 4k and 600 for the 8k. But check your directions to make sure.

The instructions that came with the Norton states: "The 4000 and 8000 grit stones should be finished on 400-600 grit waterproof paper to leave a smoother texture on the stone surface." I interpret that to mean that both sides can be lapped with any grit paper within the 400-600 range. Yet I hear experts talking about using different combinations than the "official" recommendation. That is what has me confused. Maybe these experts have found other grit size paper to be even more effective than the manufacturer's recommendation. Right now I'm leaning toward using 600 grit paper for both the 4 & 8K sides. Does anyone wish to offer a different solution? Thanks.