Sharpening and/or Sanding Oil

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Robert LaLonde

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I need to polish up some steel parts. I grew up sharpening knives (among many other chores) in our family's country grocery store. We had a really nice triple stone I learned to use with which I could put a tomato peeling razor edge or a bone chopping hatchet edge. No stropping required, and if you had to put a steel to my blade it was because you abused it or used it for the wrong purpose. To be fair I could steel a fine edge to save a trip to the stones, but most people do a lot more damage than good with a steel. Anyway, We always used mineral oil on our stones. Plain old mineral oil from the HBA aisle in the store. I thought it worked great. I still use it today for finishing a blade on the stone (I have a nice long tri stone setup in my shop), although I rarely use the coarse stones any more. I tend to reshape a badly abused blade on the bench sander. Its just so much faster if you are careful not to overheat the tip. Now I have seen the various tiny little cans of over priced oil sold private labeled for "arkansas stones," and I tried it a long time ago. It didn't work as easily in my opinion as plane old mineral oil. I've seen a few others but just figured they were similar snake oil.

Now before we get the usual array of "Well I use!!!!" comments I'd like to clarify. I've decades of experience sharpen knives and I probably sharpened more knives than most of you (certainly not all with respect to those with more experience) have in a lifetime before I was 15. Since I quit working for the family in my early 20s I've probably only averaged sharpened the same as the rest of you though. I know how to sharpen a knife, there is no one perfect angle or grind, and plane old mineral oil will work just fine. I'd like to know if anybody who has a lot of experience using mineral oil as a sharpening oil has found something that works definitively better as a sanding and polishing oil for modestly hard steel parts. (Typically RC28-RC32)

What got me thinking about this was that when I was picking out a selection of fine grit papers for final finishing before going to the buffer I noticed the packages said good for polishing steel when used with oil. I don't think I ever saw or maybe just never noticed that before. For sanding I always used water, and found that the coolant mix out of my milling machines works pretty well.
 
I used to use plain old mineral oil from the HBA aisle for spindle oil for my 9" SBL for many years. Never thought about using it as honing oil. Have to try it.
 
Bob,

Could you explain to me what a steel is and how and when to use it? Another thing that puzzles me is why is mineral
oil better than motor oil or way oil for sharpening? Thanks.
 
For most people the answer to when to use a steel is NEVER!!!!!!!!!!!! A steel is just that. A steel rod used to straighten a folded edge.

As to whether or not mineral oil is "better" than those you mentioned I can't tell you. I am neither a physicist nor a chemist. However mineral oil is pretty much non-toxic, has no addittives that could make it noxious or toxic, and historically been consumed by homo sapiens with little ill affect. That in and of itself makes it a better choice for knives than other oils in my opinion. The fact that it does a great job doesn't hurt. Sure knives for food prep are cleaned and sterilized, but there can still be some small chance of residue.
 
I worked in a auto machine shop and to hone the cylinders we used Sunnen brand honing oil. It came in gallon size steel cans. I filler several lighter fluid cans with it and finally bought my own can. I'm about out of it now so I will be trying to find it again. The smell will take me back to the shop with Marvin and Woody......long gone but still in my memory.
 
If it touches food I use olive oil. The course i took on environmental engineering class reinforces the notion.
 
I have one of the tri stones made by Norton that I use for sharpening woodworking tools, it came with a container of the mineral oil, which has been stated is the go to oil for knives in contact with edibles. I thought it was rather heavier than would be ideal for other purposes than food prep, and tried a light spindle oil; I like it better than the mineral oil, the stones seem to bite better.
 
White oil or light mineral oil, is great for hand sharpening knife blades.
it comes in many viscosities as the light may imply
there is light, medium, and heavy mineral oil in my industry.
as a matter of fact light mineral oil is the only lubricating substance accepted in a USDA inspected facility for sharpening meat cutter (butcher) knives.

in a USDA inspected production plant, the meat sawblades, meat grinding components, and meat cutter's(butcher) knife blades are cleaned and sanitized, then stored with Mineral Oil encapsulating the all aforementioned after every shift.
it's considered non-toxic unless turned into a vapor, then it becomes an inhalation hazard
 
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