In this post I'll discuss what I've learned about the different bench stones used to sharpen woodworking tools over the last month or so, I'm by no means an expert, but with my machining background I feel I was able to pick this up relatively quickly. There are many different ways of achieving the same end result, and the key here is to choose a system/method and just go with it, don't get to hung up on which is better, it's really just a matter of personal preference - find something you like and learn to achieve that end result - a sharp tool.
I'll start with the simplest option: a piece of float glass and varying grades of abrasive sheet. I've seen this called the "Scary Sharp" system by some woodworkers, but backyard mechanics have been flattening cylinder heads using this method for decades. Float glass is the flattest glass commonly available, it's made by floating molten glass on top of a bath of molten tin. Abrasive sheets come in all kinds these days: regular sand paper, wet/dry paper, micro abrasives on Mylar sheets, diamond coated films, and plastic laminate sheets with lapping compounds. Sheets can come with or without a PSA (Pressure Sensitive Adhesive) backing, a spray adhesive can be used with sheets without PSA. When using a sheet without adhesives, be sure to break the back of the sheet by running the back against the edge of the bench - if you leave the curl facing up the sheet it will round the edge of your tool - a very undesirable thing to do. This system is quite inexpensive to get into, but can get quite expensive when you factor in the consumable sheets over time. I do think that float glass is a handy thing to have around in any workshop, you never know when you may want to flatten a cylinder head. Most bench stones are around 3x8" so the larger surface of 10x12" will hold a full size abrasive sheet, the larger surface comes in handy when working with larger pieces like a plane body. Other options for float glass is a cheap granite surface plate (never use abrasives on a surface plate used for precision layout or measurement!), a large marble tile, or a off-cut from a granite counter top - I don't really know how flat these latter options are, but worth trying if you can pick them up for free.
Next there is oil stones, probably one of the older methods. I don't have any experience with the natural Arkansas stones, but I have used Norton manufactured aluminum oxide oil stones for years in industry - one of the reasons I went with water stones for my woodworking, I like trying new things. Oil stones require a light oil to prevent them from clogging, one of the reasons they are still used today extensively in industry is the fact that oil is used, it prevents rust from forming on machine components. The type of oil used is usually a honing oil typically a light mineral oil, I'd recommend sticking to a brand name honing oil such as Norton's. Specifics on oils is a deep rabbit hole indeed, that said, I've used WD-40, and used varsol for honing - both worked fine, I've also heard of guys using diesel fuel or kerosene. Stinky, not to mention the carcinogens, not something most of us would enjoy in a wood shop. Stropping is usually done after the tool has seen the stones, to remove the burr and to polish the edge to a finer point than possible than with oil stones alone. Stropping is done on either a leather strop or even a piece of 3/4" MDF. Strops are loaded with an abrasive wax or paste, like jewelers/buffing rouge, the bar of abrasive is simply rubbed into the surface of the strop. Sharpening kitchen knives with oil stones should be avoided, unless you are using food safe honing oil on your stones.
Water stones are our next option. Water stones have a long history of use in Japan, the best natural stones are scarce and fetch big money today, and are typically used in traditional sword making. Today's manufactured stones are readily available from Japan and North America. Lee Valley has a write up on the water stones they sell. I opted for the Norton water stones, and went with the full selection of stones, including their flattening stone. Save your money don't bother with the flattening stone, it sucks - the flattening stone will go out of flat itself. I also didn't like the 220, it comes apart too fast for my taste creating a sloppy mud, so save your money there too. The 1000, 4000 and 8000 stones are quite good though. There are ceramic water stones available, I haven't tried them yet, but what I've read of the Shaptons is pretty good, they also make 16,000 and 30,000 grit stones, interesting. The more traditional water stones require a soaking in water before they can be used, something that can be a problem. Ceramic water stones only require a quick spraying of water before use, a lot more convenient, while cutting faster than the traditional stones.
Here is a video from Lie-Nielsen on sharpening a plane iron, using water stones, as well as David Charlesworth's "ruler trick" which saves a ton of time, by the way, if you ever get a chance to watch Charlesworth's videos, do so, they are brilliant.
Both oil and water stones need to be maintained flat. If you don't flatten your stones, you'll waste a lot of time shaping your tool to the same shape as your stone each time you change stones. I use DMT's Dia-Flat diamond lapping plate and it's awesome. Each one is checked for flatness by hand to be within 0.0005", and it can be used for flattening either oil or water stones. Other alternatives include using a glass plate along with 220 wet/dry paper or a course diamond bench stone.
Here is Lie-Nielsen's video on stone flattening, in it Deneb shows braking an abrasive sheet back against a sharp edge, a very good tip:
Diamond bench stones are yet another option. They have come down in price so much that I would recommend them over both abrasive sheets and stones for the courser grits. They cut fast, do not require flattening, are cleaner in use than the other options, more versatile (you can use them to hone carbide and stones), and they are long lasting. The course diamond stone can also be used for flattening your water stones. I have tried the 8000 extra fine DMT stone and I don't like it, it has an odd feel to it, I much prefer using a Norton 8000 water stone, it's more forgiving and I prefer the feel. I have a couple DMT stones that are 2x6" this size is too small, go for the bigger 3x8" it's much more usable, I have the 220 in that size and it's badass. They also have a couple in 4x10" which would be worth considering. Other manufactures of diamond bench stones include Trend and Shapton. I do prefer the continuous surface of the Dia-Sharp from DMT, they make honing smaller surfaces much easier and they produce more consistent surfaces.
Here is a video of Paul Sellers using diamond stones and a strop, note the free hand technique:
Yet another option are lapping plates. Lee Valley stock a couple different machined lapping plates along with a variety of lapping compounds, I've done my fair share of lapping of machine components, it's messy, and the lapping plates will go out of flat with use. Lapping is a precision finishing technique usually used for producing extremely flat surfaces - flatness that can be measured in light bands. Far from an ideal sharpening process in my opinion, it would work however and I'm sure there is someone out there who swears by it.
As you can see, there are tons of different sharpening systems, and one could spend a lot of time and money trying different methods, but in practice all one really needs to sharpen and maintain tools is a 1000, 8000 grit stone, and some sort of courser stone to shape tools and flatten stones. So a bare minimum kit that I would recommend is a 1000/8000 Norton combination stone, and either a course diamond stone (220 or 325) or float glass with course wet dry paper (180 or 220). You could do a lot with just those three abrasives. I've come across forum posts where guys are using diamond plates up to 1200, and then are using the Shapton ceramic stones to finish - the best of both worlds. Don't corner yourself into thinking that you can only use on system and one system only, a hybrid system will have it's advantages, not to mention you can tailor it to your tastes. Remember, it's the sharp tool that matters, not how you get there.
There is a lot of information I didn't touch on, like the fact that grit size isn't standardized, the different abrasive types, or the bond types used in the stones, honing guides, honing technique, tool geometries, tool steel metallurgy, or sharpening by machine - which is all outside the scope of this post. I'll return to some of these subjects in future posts.
I'll start with the simplest option: a piece of float glass and varying grades of abrasive sheet. I've seen this called the "Scary Sharp" system by some woodworkers, but backyard mechanics have been flattening cylinder heads using this method for decades. Float glass is the flattest glass commonly available, it's made by floating molten glass on top of a bath of molten tin. Abrasive sheets come in all kinds these days: regular sand paper, wet/dry paper, micro abrasives on Mylar sheets, diamond coated films, and plastic laminate sheets with lapping compounds. Sheets can come with or without a PSA (Pressure Sensitive Adhesive) backing, a spray adhesive can be used with sheets without PSA. When using a sheet without adhesives, be sure to break the back of the sheet by running the back against the edge of the bench - if you leave the curl facing up the sheet it will round the edge of your tool - a very undesirable thing to do. This system is quite inexpensive to get into, but can get quite expensive when you factor in the consumable sheets over time. I do think that float glass is a handy thing to have around in any workshop, you never know when you may want to flatten a cylinder head. Most bench stones are around 3x8" so the larger surface of 10x12" will hold a full size abrasive sheet, the larger surface comes in handy when working with larger pieces like a plane body. Other options for float glass is a cheap granite surface plate (never use abrasives on a surface plate used for precision layout or measurement!), a large marble tile, or a off-cut from a granite counter top - I don't really know how flat these latter options are, but worth trying if you can pick them up for free.
Next there is oil stones, probably one of the older methods. I don't have any experience with the natural Arkansas stones, but I have used Norton manufactured aluminum oxide oil stones for years in industry - one of the reasons I went with water stones for my woodworking, I like trying new things. Oil stones require a light oil to prevent them from clogging, one of the reasons they are still used today extensively in industry is the fact that oil is used, it prevents rust from forming on machine components. The type of oil used is usually a honing oil typically a light mineral oil, I'd recommend sticking to a brand name honing oil such as Norton's. Specifics on oils is a deep rabbit hole indeed, that said, I've used WD-40, and used varsol for honing - both worked fine, I've also heard of guys using diesel fuel or kerosene. Stinky, not to mention the carcinogens, not something most of us would enjoy in a wood shop. Stropping is usually done after the tool has seen the stones, to remove the burr and to polish the edge to a finer point than possible than with oil stones alone. Stropping is done on either a leather strop or even a piece of 3/4" MDF. Strops are loaded with an abrasive wax or paste, like jewelers/buffing rouge, the bar of abrasive is simply rubbed into the surface of the strop. Sharpening kitchen knives with oil stones should be avoided, unless you are using food safe honing oil on your stones.
Water stones are our next option. Water stones have a long history of use in Japan, the best natural stones are scarce and fetch big money today, and are typically used in traditional sword making. Today's manufactured stones are readily available from Japan and North America. Lee Valley has a write up on the water stones they sell. I opted for the Norton water stones, and went with the full selection of stones, including their flattening stone. Save your money don't bother with the flattening stone, it sucks - the flattening stone will go out of flat itself. I also didn't like the 220, it comes apart too fast for my taste creating a sloppy mud, so save your money there too. The 1000, 4000 and 8000 stones are quite good though. There are ceramic water stones available, I haven't tried them yet, but what I've read of the Shaptons is pretty good, they also make 16,000 and 30,000 grit stones, interesting. The more traditional water stones require a soaking in water before they can be used, something that can be a problem. Ceramic water stones only require a quick spraying of water before use, a lot more convenient, while cutting faster than the traditional stones.
Here is a video from Lie-Nielsen on sharpening a plane iron, using water stones, as well as David Charlesworth's "ruler trick" which saves a ton of time, by the way, if you ever get a chance to watch Charlesworth's videos, do so, they are brilliant.
Both oil and water stones need to be maintained flat. If you don't flatten your stones, you'll waste a lot of time shaping your tool to the same shape as your stone each time you change stones. I use DMT's Dia-Flat diamond lapping plate and it's awesome. Each one is checked for flatness by hand to be within 0.0005", and it can be used for flattening either oil or water stones. Other alternatives include using a glass plate along with 220 wet/dry paper or a course diamond bench stone.
Here is Lie-Nielsen's video on stone flattening, in it Deneb shows braking an abrasive sheet back against a sharp edge, a very good tip:
Diamond bench stones are yet another option. They have come down in price so much that I would recommend them over both abrasive sheets and stones for the courser grits. They cut fast, do not require flattening, are cleaner in use than the other options, more versatile (you can use them to hone carbide and stones), and they are long lasting. The course diamond stone can also be used for flattening your water stones. I have tried the 8000 extra fine DMT stone and I don't like it, it has an odd feel to it, I much prefer using a Norton 8000 water stone, it's more forgiving and I prefer the feel. I have a couple DMT stones that are 2x6" this size is too small, go for the bigger 3x8" it's much more usable, I have the 220 in that size and it's badass. They also have a couple in 4x10" which would be worth considering. Other manufactures of diamond bench stones include Trend and Shapton. I do prefer the continuous surface of the Dia-Sharp from DMT, they make honing smaller surfaces much easier and they produce more consistent surfaces.
Here is a video of Paul Sellers using diamond stones and a strop, note the free hand technique:
Yet another option are lapping plates. Lee Valley stock a couple different machined lapping plates along with a variety of lapping compounds, I've done my fair share of lapping of machine components, it's messy, and the lapping plates will go out of flat with use. Lapping is a precision finishing technique usually used for producing extremely flat surfaces - flatness that can be measured in light bands. Far from an ideal sharpening process in my opinion, it would work however and I'm sure there is someone out there who swears by it.
As you can see, there are tons of different sharpening systems, and one could spend a lot of time and money trying different methods, but in practice all one really needs to sharpen and maintain tools is a 1000, 8000 grit stone, and some sort of courser stone to shape tools and flatten stones. So a bare minimum kit that I would recommend is a 1000/8000 Norton combination stone, and either a course diamond stone (220 or 325) or float glass with course wet dry paper (180 or 220). You could do a lot with just those three abrasives. I've come across forum posts where guys are using diamond plates up to 1200, and then are using the Shapton ceramic stones to finish - the best of both worlds. Don't corner yourself into thinking that you can only use on system and one system only, a hybrid system will have it's advantages, not to mention you can tailor it to your tastes. Remember, it's the sharp tool that matters, not how you get there.
There is a lot of information I didn't touch on, like the fact that grit size isn't standardized, the different abrasive types, or the bond types used in the stones, honing guides, honing technique, tool geometries, tool steel metallurgy, or sharpening by machine - which is all outside the scope of this post. I'll return to some of these subjects in future posts.
