Thread: Frequency of Lapping Natural Waterstones?

Do natural waterstones need to be lapped very frequently? It seems like they would because each time you use them you make a slurry with the rubbing stone. Inevitably, one would remove material unevenly from the stone and it seems to me that this would make the stone uneven with even a few uses. Would owning a Thuringen/Escher/Coticule be high or low maintenance?

I find my Coticule low in maintenance in comparison with my Norton. (Coticule lapped 1 time in a year - Norton Lapped 2 times in 1 month).
On the other hand you can't really compare these two... I;m in love with both as I seem to get an edge on every razor with this combo

I theory every rubbing with the slurry stone will make them less than flat unless your slurry stone is wider than the base stone and you use perfectly even pressure and run the entire length of the stone. It's the same as running your razor over the stone, after even one honing it will no longer be truely flat anymore.

We are talking on a very small scale but it wears none the less.


It might be fun to experiment here. I have a Cordax measuring machine in our lab (day job guys, not in the strop shop <g>) and might test a newly lapped stone to see just how "un-flat" it really is, then after a half dozen honings and/or slurryings to see how it changes. The machine will read to .0001, one ten thousandth of an inch and can be programed to give an overall flatness reading.

My day job is manager of a materials testing/NDT lab for an aerospace foundry and machine shop. We (I)do dimensional, spectroscopic, radiographic, liquid penetrant and physical properties tesing there. Might be a fun experiment to try this out.

Tony

A natural stone like a coticule is very hard. Much harder than the razor. There should be almost no wear even if you use the hone for 100 years. You will see old natural stones being sold that are 50-60 years old and they have never been lapped and they work fine. Of course if you use a slurry stone of equal or higher hardness you will be wearing down the stone to a varying degree. Similar to jewels used in watches. The brass or steel watch parts impact the synthetic saphire or ruby constantly and the jewels last indefinately. The garnets in the coticule aren't as hard but the difference between them and the steel is very great.

On the other hand a stone like the norton is being constantly ground down by the razor so lapping will be required on a regular basis depending on how much its used and the pressure applied during honing.

Bigspendur,

I'm gonna have to disagree on this one. Many natural stones comprise a hard abrasive nested in a soft matrix. That matrix will easily wear away. I have dealt in many vintage Belgians and Eschers and at least half have required serious lapping to achieve a flat surface again. Most had a deep hollow in the center, end to end, as well as a dip to one side all from uneven honing presure.

Each natural stone is different. My Chinese stone from Woodcraft is very hard and very little was removed in it's initial lapping. On that one I would agree that you could hone a liftime and not wear it out. Many of the vintage Eschers will almost melt away when lapping and will wear fairly fast under the steel of a razor as well.

Not saying your wrong, just saying my experiences were quite different with many natural stones.

Take care,
Tony

Yup. Even arkansas stones, which have a hard abrasive in a hard matrix, will still wear down surprisingly quickly. It takes a while to accumulate significant wear if you're honing a pocketknife, but razors aren't nearly as tolerant and it doesn't take much wear to make a difference. Slurry stones are probably more tolerant than a simple wetstone though because of the slightly different cutting mechanism.

I agree it would depend on the matrix as to how fast the stone will wear. If the matrix is too soft it will melt like butter and the garnets that do the cutting will just come out of the matrix too easily and do nothing. The trick is finding a stone that has a very hard matrix with a hardness of 5 or better and the garnets embedded in that. Then it will last forever. I don't know the matrix in the coticules so I can't say for sure though it seems pretty hard to me. There are several candidates I can think of offhand but they would be too expensive to use for hones.