Lather in Whetstone - What is the Effect?

[rbscebu]

I have read that some hone using shaving lather or a drop or two of detergent on their whetstone(s). How does this affect the resultant scratch pattern on the bevel? Say I hone on a 10k with plain water and then hone on the same 10k whetstone with shaving lather/detergent.

 

[Legion]

Breaks the waters surface tension and provides lubrication, which effectively allows the blade to ride more smoothly over the hone. 10k is still 10k, but I guess it is like having a lighter touch.

Anyway, anecdotally people find it gives a finer edge with some types of hones. Usually non-porous ones like Coticules, barber hones and Thuringians.

 

[bluesman 7]

It's that cushion property of lather that DE users talk about. I've always thought that for straight shaving cushion was a negative, hence the thinner wetter lather.

When I use my Washita for knife sharpening, I use a combo of water and propylene glycol. The more PG I use the finer the stone cuts up to finishing on straight PG. Same thing.

Warning; some detergents are not compatible with some water stones. I've read where someone has a damaged area on a Norton water stone where a drop of Dawn hit the stone.

 

[DrStrange]

Water is highly polar and when the blade face and the hone have polished
each other so that the layer of water between them is about one molecule thick,
then the water gets sticky and it becomes difficult
to move the blade smoothly against the stone (stiction).
Detergent will break up stiction.
The point of my using the detergent,
is to be able to keep going using a lighter touch.
I only use the detergent on slate stones.
I figure slate is considered to be one of the more durable roofing materials
so slate can probably handle a little detergent.
I don't use detergent with synthetic stones and I don't use it with shale either.
I've never gotten stiction when there was slurry on a stone.
I wouldn't expect any problems with detergent on cryptocrystaline quartz hones either,
though I don't have a lot of experience with that.

 

[rbscebu]

I currently only have synthetic stones available up to 10k. I was hoping that using lather would increase the effective grit rating before going on to diamond pasted balsa stops.

 

[DrStrange]

1.0 micron diamond is about 16k.
0.5 micron is about 32k.
I don't think either of those grits would be unreasonable after 10k.

 

[Legion]

I currently only have synthetic stones available up to 10k. I was hoping that using lather would increase the effective grit rating before going on to diamond pasted balsa stops.

No. You will just end up with a hone full of soap.

Don't use anything other than water on a hone you have to soak, IMO.

 

[RayClem]

When using synthetic hones, I use water only. However, with some of my natural hones (12K and finer), I have used shaving lather as a lubricant. However, more frequently, I will use a few drops of liquid hand soap such as Softsoap. I will start honing and then slowly add water until all the soap is gone and I am honing on a clean stone under running water. That seems to produce the finest edges.

 

[Basil]

I use a drop of soap on my coti it just lightens the touch to give a little finer edge.

 

[LJS]

Many barber hones (synthetic) mentioned use of lather in their instructions, but I wouldn’t on any modern synth waterstone. I do like lather on some other stones like slates and coticules. I’m not a soapy-water user, but I like lather sometimes for tweaking a finer finish than a stone would naturally deliver.

 

[Gamma]

Shapton's instructions tell us to not put soap on their stones. I think this is good advice across the board for synthetic waterstones with binders like Shapton and Nani use. Soap will get into the stone, because they are porous. Water will evaporate, soap does not. Water attracts/holds onto moisture, which isn't good for binders. The soap itself is detrimental to the binders also. There was a guy on SRP that ruined his Norton combo doing this. Norton/St Gobain was unable to say whether or not using soap could be harmful to their stones, nor could they explain a good reason to use it. Lack of testing was the reasoning. They sorta refused to respond to my question about soap build up with repeated use. Soap scum is nasty stuff. Can't be good to flirt with that in a fine whetstone.

I have gotten soap on synths accidentally a couple of times, and it stained the material deeply. under magnification a scratch test showed that the stained area was softer which isn't something I am looking for in a higher grit synth. Even in coarser grits I find it questionable.

Water, on its own, is an excellent lubricant and it flushes swarf away correctly. It's my personal thought that if more lube is needed then something is wrong with technique. Adding more lube doesn't make the stone finer, all it does is emulate using a lighter touch. A 10k stone isn't going to become 12k. The 10k stone with soap is still 10k and with correct light touch max results are achieved regardless.

At the same time, stones are tools and I have ground back tools to suit a specific application or two so it's not that tools can't be 'adjusted' to suit a user. For me it becomes a matter of what my investment is, and what possible outcome a modification can deliver. Logically, I see no gain in using more than water on a water stone, none that can't be delivered by using the stone correctly anyway. While some people have said using soap is better, it's always just because they said so. Logic, reason, and how the stones work say otherwise to me. I have monitored using super hard Arks with oil, water, and other honing mediums and the stone's performance does not change. What does change is the feel, glide and so on...edges all come out the same. Swarf looks different using different mediums, people mistake that for an indicator of 'cutting' when it's just that oil suspends particulate better.

I guess if I had 3-4 10k stones I might cut one down and sacrifice one piece by soaking it with soap or oil just to see what happened over the long term. Because maybe it would take a year or two for the chemistry to go screwy. I thought about buying a bearmoo stone for this but since those stones are junk to begin with I don't think a test would make for much of a comparison. It's not something I'd do to my one and only 10k, or whatever k though.

 

[kcb5150]

I wouldn't put soap near a waterstone unless it were a gamble to reclaim utility. I have had waterstones I bought from fleas before with enough oil cross contamination to be problematic and fed them soap to try purging the oil so it would accept water again but then you trade one problem for another and the thing has suds trapped inside doing sketchy things. Some reacted more or less ok, others crazed badly but I didn't really care as the stones were almost free and I was learning. I wouldn't do it to a nice clean stone I paid good money for.

 

[Legion]

I soaked a stone that turned out to be a synth in simple green one time. That was pretty dumb.

 

[rbscebu]

I am coming to the conclusion that I will only use plain water on my synthetic stones. That you all for your guidance.