13. CUTTING GLASS

The primary requirement for accurate glass cutting is a smooth, clean working surface. It must be smooth because any irregularities may cause breakage through uneven pressure when cutting. It must be clean so that the glass will not be scratched if it is shifted. Flaws in the glass such as air bubbles are bad enough but scratches show up as black lines if a light mat is used. As suggested in the section on assembling, a large, sturdy bench is essen­tial which can be covered with heavy wrapping paper or sheets of cardboard kept aside for the purpose. The cardboard can be used over and over again.

A good straightedge of the non-beveled kind will be found necessary. Scotch tape attached to the under­side will help prevent slipping and extra precautions must be taken against this happening. Because glass has such a smooth surface, it may be necessary at times to drive brads into the surface of the bench to keep the straightedge in the proper place.

A glass-cutter as described in the list of tools is all that remains necessary. Glass-cutters with diamond points last forever, but their extremely high cost make them only practicable to those whose trade is glass-cutting.

The cutting of glass is not difficult and the relative cheapness of the material allows beginners to break a few pieces. Even the artist who works only with oils and does his own framing may be called upon occa­sionally to frame one of his black and white sketches under glass, so for anyone doing framing, glass-cutting should be learned. It is interesting to compare the price of a piece of glass cut to size and purchased in a retail store with the small cost of doing it oneself.

Brush the surface intended to be used for glass-cutting clean before laying the glass down and meas­uring. After it is in position, place the straightedge down in approximately the right place. Now drive two brads long enough to project above the straightedge so that it will not slide towards the left as the cutter is drawn along its right side. Taking an accurate ruler, place it on the straightedge at right angles and extend­ing towards the left. The wheel on the glass cutter is slightly less than ⅛" from the bearing surface of the cutter. This difference must be taken into account when measuring. For instance, if a piece of glass were to be cut to exactly 20", the measurement from the right hand edge of the straightedge to the left hand edge of the glass would be slightly more than 19⅞".

After sliding the glass under the straightedge, mea­sure the top and bottom to see that they are equal, then grasp the cutter in the right hand like a pencil placing the index or middle finger in the curved part provided for it. Holding the cutter at a slant and start­ing as close to the furthest edge but never beyond it, draw the cutter towards yourself giving it firm, even pressure and letting it slide off the nearest edge. An even, scratching sound will be heard and if it has been correctly done, the glass will be "started" in the same way that a piece of ice or a diamond is split.

Lifting the glass carefully by the largest part, tap gently at either end of the cut with the handle of the cutter. Tap on the under side of the glass opposite to the cut and only at the beginning or the end of the cut. The glass will be seen to split. The waste area can now be grasped and by bending slightly, parted.

Practice on scrap pieces of glass, making the line as straight as possible. Try different pressures until one has become accustomed to the correct amount and also to the degree of slant. It requires a trick or a knack but it can be learned by anyone in ten minutes.

Never go over a line once cut and never cross a cut line. It will only dull the cutter and break the glass. It is better to discard the glass and save the cutter.

Cutting oval or irregular shapes is not difficult but merely requires a steady hand since they are cut free­hand. Lay the glass over a pattern and follow the line. Leading lines, curving away from the cuts are then made and the pieces broken off in sections.

The glass cutter should always be kept in turpen­tine. This is not only to protect it from rust, but be­cause the slight, oily film makes for smoother cutting. Generous amounts of oil should be left on the cutter when cutting very old or extra thick glass. Glass gets brittle with age.

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