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Marble 'Pontil' Variations This page is graphics intensive and takes a long time to load. Below is a brief description on the difference between handmade marble finishing, or lack there of, and a comparison with machine made marble cut or shear mark variations. For more information, see marble production methods, or visit the glossary page.
The four photos above display a 'ground' pontil. This was created by grinding or abrading the rough spot that was left on the marble with a grinding wheel or like device. The earliest marbles made in German by Elias Greiner were finished with this method. This method was probably dropped and fazed out over time to lower the price of the finished good by removing a step from the manufacturing process. Notice the fine linear striations in the upper photos that are resultant from a grinding process. The upper right photo also shows multiple fine grinding marks that almost leave a 'faceted' appearance on the glass. These upper marbles were finished with a fine grit grinding wheel. The bottom two examples were ground with a wheel that was not as fine.
The four photos above display a 'regular' pontil. This is created by simply knocking the marble off of the gather or rod from which it was just cut and formed from. It has not been treated at all. Notice the fine crazing on the glass from the prolonged contact with the metal cutting surfaces of the 'marble shear'. Sometimes the cut on the opposite pole has a fire polished appearance due to its being reheated in order to cut the next marble off of the cane or gather.
The six photos above display 'melted' pontils. This design was patented by James Harvey Leighton in Akron, Ohio. This pontil was created by first knocking the marble off of the gather like the groups above, but then the marble was subjected to a gas and compressed air torch to melt and reheat the blemish spot. The pontil was then smoothed over with a hollow shaped forming tool to smooth this spot down further. See Mr. Leighton's patent.
The marks seen on the four photos above are not pontils. They are cut lines or shear marks. All of these marbles were made by the M.F. Christensen & Son Company in Akron, Ohio. The cut in this case was made with a pair of hand operated scissors or glass shears. The glass was hand fed into a machine but the machine actually makes the marble round in this case. All of the previous methods were completely formed by hand. Notice how the marks are longitudinal and show exactly where the cutting tool separated the glass charge to be fed into the machine from the larger gather of glass. This mark looks similar to seam marks on later marbles because it was formed in essentially the same way- except later marbles were sheared by a machine rather then a human being. This marble type is not a handmade- it is machine made.
The four marbles shown above are referred to as 'crease' pontil marbles. These marks are not really pontils either but are really just drastic shear marks. The shear may have been hand operated or automatic. These marbles are believed to have been made in Japan since they are found in labeled boxes marked such. My idea on why these shear marks are so pronounced is because the glass that was employed to make these marbles had a shorter working range then compared with the glasses used at a company like M. F. Christensen & Son shown above. With more heat available for the forming process in the M.F. Christensen marbles above, the chilled area is able to compensate for localized heat loss better then the lower temperature Japanese glass and thus smooth itself over better. If the temperature is lowered on one spot on the marble through contact with a metal cutting device , a rough cut mark will be the result, because the metal tool will act as a heat sink and will deprive the glass area right near the cut line of the needed thermal energy that would act to soften the edges off and make the cut line less drastic. The lower temperature glass is at a disadvantage in terms of workability, but lowers the fuel consumption considerably; Japan is not rich in fossil fuels. This marble type is not a handmade- it is machine made.
The two marbles above display what is called a 'pinch' pontil. These marks are not pontils either and are really just sloppy yet distinct shear marks. The shear may have been hand operated or automatic. The marbles that display this mark seem to be hand gathered but machine formed. This marble type is not a handmade- it is machine made. These marbles seem American made, and are probably from the Christensen Agate Company while operating in Cambridge, Ohio. Evidence is still needed to prove the origin place of this marble type. All of the images above were taken at 60 power with a microscope.
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