Granite surface plate maintenance.

I found the following advice on another discussion forum and I've never heard this particular caution before.

I use glass cleaner for the granite stuff. You want to keep oil off, if oil is allowed to stay on granite for an extended time, it can soak in and cause it to swell.

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Water causes wood to swell, some chemicals cause some polymers to swell, but oil causing granite to swell? I don't know what the old fart equivalent of an old wives tale is, but is this belief in that category?

I can imagine that someone somewhere has seen a granite plate with differential temperature changes and an oily surface, leaping to a cause and effect conclusion. Or have I been that ignorant all these years? We always cleaned the surface (and the workpiece) to be sure no dirt or swarf changed a measurement but didn't get excited about oil. Not that it was ever rubbed down with oil, but parts out of the EDM tank, grinder or something else weren't seriously de-greased before measuring.

TGTool said:

I found the following advice on another discussion forum and I've never heard this particular caution before.



Water causes wood to swell, some chemicals cause some polymers to swell, but oil causing granite to swell? I don't know what the old fart equivalent of an old wives tale is, but is this belief in that category?

I can imagine that someone somewhere has seen a granite plate with differential temperature changes and an oily surface, leaping to a cause and effect conclusion. Or have I been that ignorant all these years? We always cleaned the surface (and the workpiece) to be sure no dirt or swarf changed a measurement but didn't get excited about oil. Not that it was ever rubbed down with oil, but parts out of the EDM tank, grinder or something else weren't seriously de-greased before measuring.

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I agree on the old wives tales thing. Just think of all that oil based plate swelling printing ink thats been applied to granite plates over the years .
Temperature differential can make a very measurable change tho, probably responsible for most of the OMG moments

Demon73 said:

I agree on the old wives tales thing.

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Mostly. Probably.

But lest we forget.. a good deal of the "mineral" (mostly) soils on-planet were once solid rock.

"Mother Nature" breaks 'em down with water/ice freeze-thaw cycle erosion as much as by any other means.

Fair slow process "usually" - at least by human time-scales. But also one that is damned hard to interfere with effectively.

Check your surface plate condition about ten million years out. If kept indoors and dry, it will probably be in far better condition than the exposed native rock back at the quarry face it was cut from, but still..

Even if that's a seriously OLD, "old wives tale", it ain't exactly WRONG.

thermite said:

Mostly. Probably.

But lest we forget.. a good deal of the "mineral" (mostly) soils on-planet were once solid rock.

"Mother Nature" breaks 'em down with water/ice freeze-thaw cycle erosion as much as by any other means.

Fair slow process "usually" - at least by human time-scales. But also one that is damned hard to interfere with effectively.

Check your surface plate condition about ten million years out. If kept indoors and dry, it will probably be in far better condition than the exposed native rock back at the quarry face it was cut from, but still..

Even if that's a seriously OLD, "old wives tale", it ain't exactly WRONG.

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Are you arguing that a surface plate might be better served by keeping it well oiled to reduce the entry of moisture with the possible consequent freeze/thaw breakdown?

And what do we really know about the effect of petroleum reservoirs underground on underlying granite strata? Maybe that where this idea came from.

TGTool said:

Are you arguing that a surface plate might be better served by keeping it well oiled to reduce the entry of moisture with the possible consequent freeze/thaw breakdown?

And what do we really know about the effect of petroleum reservoirs underground on underlying granite strata? Maybe that where this idea came from.

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Dunno. I actually try hard to keep mine (the surface plate, too..) clean, dry, and NOT laden with any oil, wax, or anything else unless immediate use requires one of those. Actually more worried to NOT build-up any gummy or tacky residues that would be progressively harder to clean out/off than if cleaned up same hour, same day one was done using blueing for that "shift".

Ask me in ten million years on the more general issue.

Point is that whatever goes on with Granite within human-tolerable temperature ranges, it surely goes on very, very slowly as far as the ROK is concerned.

OTOH, thin a transfer media with mineral oil - polymerization is very slow. Thin with vegetable oil insread? You have just created a problem.

Otherwise, the people to ask, or the websites to search, might best be those who place, then engrave, service, & clean grave markers, not just those who MAKE them.

Rock of Ages and Herman were two that were both/all. Monument makers AND surface plate makers ANDd users of SP's.

Grave markers are outdoors in all manner of weather, acid rain, NOX smog, tree sap, molds, Lichens, Ivy, birdshat & bugscat..

Some, granite as well as marble, DO show rather severe deterioration. Others have taken on green stain from adjacent copper-sheathed church roofing runoff.