How To Run A Scored Piece Of
There are several methods of "running a score" that are used by stained
Once you have scored a piece of glass, your next step is to "run the
score" and break the piece out.
When you begin scoring a cut, always start it a little bit in from the
edge of the glass. When you end the score, you
always roll the cutter over the edge of the glass.
The best place to start running the score is always on the edge of the
glass that you ended the score line at. This
ensures that the scored piece breaks out easily and cleanly.
Here are a few
universal techniques for running a score that are used at one time or
every stained glass artisan.
- Use Your Hands
To Run The Score
The fastest method used
by most experienced artisans to run a score is to use your hands.
Make a fist with both hands and grab the glass on both sides of the
score line with your thumbs up.
Next, pull your hands apart and snap the glass up and out, just like
you would snap a wooden twig.
Your index fingers underneath each side of the score line and your
thumbs on top of the glass are used to exert the
pressure that breaks apart the glass.
For large longer pieces that weigh more, rest the heaviest part of the
glass on your work surface in case you accidently
drop the glass after it separates.
This technique is expecially useful when you are working with many
small cuts and where speed is of the essence.
Running Pliers To Run The Score
How to Use Your Running
Running pliers should always be used with the adjusting screw facing
The black line or indentation that is in the center of the top jaw
should be centered on the score line you intend to run.
If your running pliers doesn't have a center line, draw one on with a
magic marker or scribe.
Line up the jaw of the running pliers with the center line of the score
and place them about half way up the edge of the
Gently squeeze the pliers together until you hear the glass click or
Short score lines will break apart immediately.
On longer score lines you will need to repeat the process at the other
end of the score until the glass separates.
Sometimes you will need to repeat the process a couple of times, but
normally the glass will separate with only one or
Don't squish down too hard on the running pliers or you will crunch the
It is important to remember that running pliers need to be adjusted for
different glass thicknesses.
A Score Using Breaking Pliers
Instead of using your
hands, you can use breaking pliers to run a score line.
There are basically two types of breaking pliers. Those with
smooth or serrated flat jaws and those with smooth or
serrated curved jaws.
Both types work as long as you remember to place the flat jaw on top of
the glass when running a score.
If you're right handed, hold the glass with your left hand and place
the jaws of the breaking pliers next to the score.
Snap the piece off by pulling down with the pliers and your left hand
at the same time, just as you would using your
hands in the first scenario.
For small pieces, use two pairs of pliers to snap the pieces apart.
Whenever you run a score make sure you pull the pieces apart as you
make your snap.
- Run A Score
Using A Pencil, Nail or Dowell
A pencil, nail or any
other small diameter object can be used to run a score line.
Just place the pencil directly underneath the score line and quickly
press the glass down on both sides of the score at
the same time.
This method achieves a clean break every time and works well on all
glass thicknesses. Just increase the diameter of the
nail as the thickness of the glass you are running increases.
A Straight Score Using A Paint Stirrer
You can use any
relatively thick straight edge to run a long score line including a
paint stirring stick.
Just place the straight edge directly under the entire length of the
score line and quickly press down on the glass, on both
sides of the straight edge.
This method works just like a pencil or nail, except it is preferred
for longer score lines. You can use any object that is about
1/8" thick to run a score using this technique.
- Using A Table
Edge To Run A Score On Large Pieces
This technique is used
by professional glass companies for running long straight scores on
larger pieces of glass such
as window panes.
After you have scored the glass, pull the piece so the score line is
about 1/4" from the edge of the table, hold the glass
firmly with both hands, lift it a few inches from the table and quickly
bring it down over the edge of the table to snap it.
You need to jerk the glass down hard over the edge of the table, so
don't be overly cautious. On the other hand, don't
slam the glass down so hard that you can't control the break.
Make sure that the score line is not directly on the edge or just over
the edge of the table. This could result in an uneven
break with possible jagged edges.
- Using A "Back
Score" Tough Cuts
There are times when no
matter what running technique you use, a piece of glass will just not
When this happens it's
time to try this technique.
- Place the piece of scored glass on the back side of a
ceiling tile or any other work surface that has some give to it.
You can use an old blanket, several layers of newspapers, an accoustic
ceiling tile or whatever.
- With a magic marker, trace the score lines on the reverse
of the piece of glass that is giving you trouble. A light
or placing the glass up to a light source be necessary to do this with
some types of glass.
- With the scored side on the bottom, gently but firmly press
along the back of the marked score line until you see it
begin to run. Using both thumbs, firmly press all along the
score line along the run until it separates.
Don't press too hard
along the back of the score or you will get an wanted break.
This technique lends
itself especially well to circles.
- The only difference is that you need to make four or more
tangent scores to within 1/16" of the outside of the circle
equidistant from each other.
- When you flip the glass over, run each of the tangent
scores and your circle will drop out of the surrounding