What Does Oil Provide When Scoring Glass?

Greetings LJ,

Worked with my Dad part time for several years way back when producing various leaded glass window inserts and panels.

We cut a lot of glass for some very large windows and never used oil or any other lube with our "scorer".

Still own it and on occasion use that same "scorer" we used back in the day.

Still scores like new.

Not saying lube is wrong or bad, just curious where you saw it used?

I always use kerosene. Dunno what it actually does, but dry makes a sound like crunching glass, while the kerosene makes a deeper sound like grinding. Both seem to break OK, but the kerosene seems smoother (confirmation bias?).

How can we find out?

Maybe to keep fine glass dust from flying around? Just a guess.

Mikerho is correct. The wide-spread use of oiling glass prior to cutting was for dust mitigation during a period of glass coloring and manufacturing that used hazardous materials.

The health hazards of cutting glass became apparent to the extent that modern glass MSDS containe statements such as:

"The coatings of the coated glasses listed in section 1 are all based on stable oxide materials, listed in section 3. These oxides are in integral part of the glass product and there is no separate exposure, but the Material Safety Data Sheet of the oxides can be reviewed for further information. Note that X-ray diffraction analysis has demonstrated that all the silica (SiO2) deposited on the glass is non-crystalline and as such does not pose a risk of silicosis."

and

"The products listed in section 1 are based on typical soda-lime-silicate flat glass. Trace amounts of the metals Fe, Se, Ni, Cr and Co are purposely added to some compositions to colour the glass and trace amounts of Pb is sometimes present as a contaminant."

Thank you JavaHead. Truly, and taking into consideration the other replies, I could think of no other reason! Thank you for the GA.

Mike

No problem, but actually spending the last 30 minutes or so looking into this further, I give significant weight to kramarat's post, #8.

There seems to be significant evidence for both positions out on the interwebs so it would be safe to say that it is dual-purposed so tossing a GA their way as well.

Thanks Java.

I've cut window panes from 100 year old glass. One thing is..............you'd better not screw up. The other thing is.................don't even think you can tackle it like modern glass.

The lubricant reduces excessive surface fractures on the surface of the glass along the edge of the score. Also helps in removing the fine dust and chips that might bind the cutting wheel and cause it to skip.

While I am not the OP, I did learn something I was not aware of - Thanks all!

After some experimentation, I have found that I can, with proper technique, cut glass in a safe predictable manner with or without lubricating the cutter. So, in terms of the final result, there is nothing gained by using lubricants.

However, I do work with glass a lot, grinding it with abrasives and i know that caution must be exercised to not inhale fine particles of glass dust. Repeated inhalation of that material inflicts damage to the lungs and sets the stage for silicosis, a deadly condition similar to the Black Lung disease suffered by coal miners.

I suspect that the lubricant is used by those who frequently cut glass, as one person here suggested: to keep the dust down.

I first saw oil used by my Dad a zillion years ago while he cut glass. I simply perpetuated the technique without questioning why.

It appears to have been just another of the many habits we perpetuate that may have served a purpose back then but which are empty and meaningless now.

Thanks to all who responded.

Case closed!

L.J.

Not quite.

Glass is much cleaner now than it used to be. Back in the day, glass had imperfections in it, air bubbles, etc.

Today we can cut glass with more pressure applied and no lubrication......................that wasn't always true. Glass cutting took longer and required several passes with less pressure applied. The oil, (lubrication), served as a shock absorber to cushion the blow, in case one hit a weak point or an air bubble, in which case the familiar "chink" sound would be heard, as a crack appeared across the pane.

OK, I gave you a GA, but I take issue with your statement:

"The oil, (lubrication), served as a shock absorber to cushion the blow, in case one hit a weak point or an air bubble, in which case the familiar "chink" sound would be heard, as a crack appeared across the pane."

For shock absorption, you need some area to work against. Seeing as the area of contact between a sharp-edged wheel and a flat surface is quite minimal, I don't see any shock-absorbing or cushioning effect happening, not to even mention that oil is not a compressible fluid!

I thought of that as I was writing, but couldn't come up with a better word or term.

Having a layer of oil between the cutting wheel and the glass helps mitigate potential damage when hitting an irregularity.

Consider your car driving down the road. Now consider your car driving down the road with no shocks, no springs, and steel wheels. The shock from every pebble would be transfered through the frame.

Also consider a tuning fork. At certain frequencies it can shatter a wine glass. Dip the tuning fork in oil and it would be impossible. The oil would absorb the "shock" of the sound waves.

The same effect would occur if the wine glass was dipped in oil.

Not exactly, The wine would taste oily.

Are shock absorbers filled with any liquid? No! They are filled with a compressible fluid, such as air. That's why shock absorbers "work"!

Unless of course, they are hydraulic. Then they use oil as a dampening agent.

Much like the oil used when cutting glass. It absorbs the shock of hitting an imperfection, turning the dreaded "chink and crack" into a slightly different pitched grinding sound.

Consider a hand grenade. Very dangerous dry. Place a live one in a bucket of oil, and you will probably get splashed. By the time the shrapnel passes through the oil, it would probably just bounce off you, if it reached you at all.

I really disagree with your assertion that liquids are useable as cushioning/shock-absorbing agents. Look up incompressible fluids and understand why, if a grenade is thrown into the water while you are submerged closeby, you will probably die, since the incompressible water will do nothing to cushion the shock - the explosive force vector that is aimed in your direction will be translated almost 100%.

The only way that liquids can be used in shock absorbers is by letting the fluid go in and out through an orifice. This does not mean that the liquid is compressible. It just means that we have found a way to utilize the properties of this fluid (liquid).

The only way that liquids can be used in shock absorbers is by letting the fluid go in and out through an orifice. This does not mean that the liquid is compressible.

Exactly..............................you have just stated the principle behind hydraulics.

Hydraulics work because the liquid is not compressible.

I really disagree with your assertion that liquids are useable as cushioning/shock-absorbing agents.

We can go on as long as you like.

OK, it seems we are in the semantics realm here.

Please answer these questions:

1) Are gases compressible fluids?

2) Are liquids incompressible fluids?

1) Yes

2) Yes (Actually the answer is no, but the degree of compression is so minuscule, that for all practical purposes, the answer is yes).

I really disagree with your assertion that liquids are useable as cushioning/shock-absorbing agents.

Are you positive that you want to stick with that position?

http://auto.howstuffworks.com/car-suspension2.htm

Here's another example:

What are the advantages of a liquid filled gauge?

Liquid-filled pressure gauges provide a number of advantages:

• The liquid absorbs vibration and pressure spikes.
• The dampening action of the liquid enables the operator to take reading during conditions of rapid dynamic loading and vibration.
• The liquid lubricates all moving elements, dramatically reducing wear in the movement.
• Because most liquid-filled gauges are filled with non-aqueous liquid and hermetically sealed, they perform in corrosive environments and are immune to moisture penetration and icing.

From here.

http://www.wika.us/service_FAQ_en_us.WIKA?ActiveID=14921

Being careful not to get between you two; when I worked in the Semiconductor Industry designing high-speed precision robotics, the nature of our systems required us to account for the compressibility of hydraulic fluid.

But, I see both sides of this debate. I think the basis of the one side, is how can a film of oil act as a shock barrier between the sharp point of a cutting tool and the material.

I have the same lack of understanding, so maybe rather than taking the direction of the debate into car shocks we could clarify the interface between the glass cutter and the glass and how oil forms an effective barrier.

For me, my mind keeps painting a picture of a razor-blade parting the oil as it cuts, leaving almost nothing between the glass and cutter and thus not fully understanding how the almost immersuarable amount remaining could provide an effective shock barrier.

OK, I'll come off that position. However, the use of the "incompressible" (yes, I took note of your distinction, and you are correct) fluid to effect dampening is due to valving. I had no idea that they did this. I think we are arguing over nothing at this point.

Oh yeah, it is used a lot, especially in the military; big guns use hydraulic fluid to absorb the shock of the firing. As the barrel recoils the fluid passes through a series of holes that decrease in size. At the beginning of the recoil stroke the oil passes through large holes. As the barrel moves further back the holes get progressively smaller restricting flow.

I agree.

As far as the thin film of oil dampening the vibrations of the cutter against the glass and helping to prevent a crack..............................I made it up. I can't find anything to substantiate my claim. However, having cut many panes of glass in my life, I do believe, (from feel, observation, and sound), that having the thin film of oil surrounding the cutter does have some dampening effect. I think if we were to look at a cut being made in slow motion, under a microscope, both with and without oil, we would be able to notice a difference in the shattering that takes place during the cut.

BTW hydraulic shocks are standard equipment. No worries.................we can't delete posts. There are probably hundreds that I wish I could make disappear.