When you're cutting stained glass,
some colors cut easier than others

Cutting stained glass, as a beginner, can be frustrating since some colors are easier to cut than others. Some cut like a knife going through butter, others will frustrate you to no end. You never know how a piece of glass will react until you start cutting it, so the more you know about glass, the better equipped you'll be to work with it.




There are basically two categories of glass, cathedral and opalescent.

Chicken Window

Cathedral glass is transparent, see through glass, and can be clear or colored. Most of the glass in this window is cathedral. See how the colors show on the wall (what you see in the picture on the outside edge of the right hand side) when the sun shines through the cathedral glass. It comes in every color you could imagine and it can be smooth on both sides or smooth on one side and textured on the other, or the front side can have some texture as well (see farther down about glass with bumps and crevices), but generally the front is smooth. Of all the cathedral glass available, ordinary window glass, although not stained glass, is the easiest to cut and the one I recommend you use when you're learning the techniques involved in cutting stained glass.





Santa

Opalescent glass is opaque. The Santa in this picture is all opalescent glass except for his face. Light passes through opalescent glass, but you can't see through it. It comes in all colors and textures.
















You will find a variety of mixtures of cathedral and opalescent, some more transparent, some more opaque, all of them made with 2 or more colors, or shades of the same color. Some are all cathedral, some all opalescent, others a mixture of both. Each mixture has a different name depending on the manufacturer. You can see them at Glass Types


Pooh Mirror

In this picture you see glass that is a mixture of both opalescent and cathedral. The blue and clear border "sky" is actually a mixture of two shades of blue and clear cathedral. The bottom "grass" is a mixture of dark and light green opalescent. This picture gives you a good example of something you need to know about glass. You should learn how to use that "just right" piece of glass in a project to make it "one of a kind" and to give it character.

To learn how to work with mirror , go Here



Take your time when you're buying glass and find that just right piece. Perhaps you will only use a little bit of one piece, or have to buy two pieces to get just what you need. Once you get serious about working with glass you'll find out that scrimping on glass just to save money doesn't work. Furthermore, you'll always find a use for the leftovers.


How Glass is Made


This is simply to show you the properties of glass and how it defines the ease or difficulties encountered when you're cutting stained glass.

The main ingredient in glass is sand. On it's own sand's melting point is so high that it is almost impossible to melt it, so potash, soda and lime are added to lower the melting point. The mixture is melted in a furnace, at an extremely high temperature. Since the mixture, without any additives, becomes clear when melted, different metallic compounds are added to create various colors. As an example, gold chloride or selenium oxide is used to make red glass, copper compounds or iron oxide are used for green glass, and cobalt oxide is used for blue glass.


How Different Colors Cut


When you're cutting stained glass, some glass cuts easier than others due to the additives used to color it. The easiest colors to cut are blue and green, and blue or green cathedral glass is easiest of all.

Some white glass is physically hard to cut. Antimony oxides or tin compounds are used to give it it's color. When you encounter a white glass that is hard to cut you need to press harder on the cutter. You don't want to see flakes of glass flying up as you score, but you want to hear a good zipper/static sound. It will break out better if you use running pliers.

Red cathedral glass cuts easier than red opalescent glass, although neither one would be described as very difficult. While you're cutting stained glass you will occasionally see a faint gold color along the score line of some red glass. That's because gold chloride was used to make the glass red, and for some reason it is visible in the score line while other colors (blue, green, purple, etc) don't have the same effect when scored.

Different brands and opacity cut differently. Practice on a small piece before you start cutting stained glass for a project. By practicing, you will learn what it involves to cut that particular glass.
*Does it need less pressure or more pressure.
*What is the best way to run the score.
*Are there bumps, seeds or crevices to cut across and how did you handle them.

Knowing how to cut the glass will eliminate many problems that you could encounter if you didn't do a practice run first.

*One more thing...you will occasionally (but rarely) run across a glass that just won't give you that zipper/static sound when you score it. If you are sure that you did a good score, but didn't hear the sound, go ahead and try to run the score. Chances are it will run exactly as it should.


When You Buy Your Glass


The colors from each glass manufacturer will cut a bit differently. For example, Kokomo blues will be different than Spectrum blues. For that reason alone, you should be aware of glass manufacturers. When you buy a piece of glass find out what manufacturer made it. Write the name on the glass. Eventually you'll be able to look at a piece of glass and know what manufacturer it and how to cut it.

Manufacturers Label

You should also write the color code on each piece of glass and perhaps keep a journal that will tell you exactly what glass you used in each project. That way, if you ever want another piece of glass for repair or to use in another project, that information will make it much easier than telling the store staff that you want that pretty blue glass with white streaks in it that you bought last year. If their store is anything like mine was, they will have many different blue streaky glasses from many different manufacturers. Being able to tell them exactly what you want makes buying glass easier for everyone. Sometimes you will be lucky enough to get glass that already has a label on it like you see in this picture.




What Side Do You Cut On?


When cutting stained glass, you cut on the front side of the glass. The back side goes towards your source of light, be it sunlight for a window panel or a light bulb for a lamp shade.

Almost all glass has a front and back side. The front side is the smoothest and/or shiniest side, the back is the roughest and/or duller side. You could relate it to a gloss versus matte finish.

Some glass is very easy to distinguish the front from the back, other glass takes some guess work. If you absolutely can't tell, then it won't make any difference. I have found that lightly running my finger tips over the surface will tell me if there is any roughness or texture to the glass.

GNA Glass

GNA is a prime example of making sure you cut on the same side no matter how many square feet of glass you use. The back side of GNA has a slightly raised pattern, which is directional as well, that quite often can only be felt, not seen until it is in a panel and in the sunlight. That's when you say Oh My! If you haven't been vigilant in making sure you have cut all pieces on the same side, your mistake will glaringly show up as soon as there's light behind it.

I always draw multiple straight lines on the front side of every single piece of GNA I will be using in a project. The lines all go in the same direction as the striations on the back. The striations are directional, so you must make sure you have them all going the same way. That will save you from finding out that you cut a piece backwards or sideways and having to repair the panel before it's even completely finished.




Using Textured Glass


Some glass will have a definite texture on the back side. Since the texture is on the back side of the glass, light passing through it causes the glass to sparkle when viewed from the front. That is the way I use textured glass for borders. However, the texture can be on the front side if that's what looks better to you or it gives the panel an unique look. I mainly use textured glass with the texture on the back, but I do use it on the front if I think the texture will give the piece more character. Remember though, when cutting stained glass, always cut on the smoothest side. If you want the texture on the front, simply turn your pattern piece over (up side down) when you're tacing it on the glass. Once the glass is cut, turn the glass over and the texture will be on the front side.

Textured Glass for Leaves

Often, glass artists will use the texture as part of their design and put it on the front side of their project, as you can see in this picture depicting leaves on a tree. Cutting stained glass on the textured side is not recommended and next to impossible to cut. To overcome that problem, simply place your pattern piece up side down on the smooth side and cut as usual. When you turn the piece over, the texture will be on the correct side. Let your imagination be your guide when you use textured glass.




Bumps, Seeds and Crevices


Glass with Bumps and Crevices

When you're cutting stained glass, you will find some glass with bumps, seeds or crevices on the front side. Seedy glass, in the picture to the left, is one example, but you will frequently find problems on the front of some opalescent glass. The trick to cutting stained glass with bumps, seeds and crevices it is to go slow and steady, and don't stop if you land in a hole or a crevice.








Finger Guiding Wheel

Use a finger from your other hand to help guide the cutter head over those difficult areas. If you keep the cutter moving it will roll into and out of the hole. If you stop, it's almost impossible to get out of the hole without lifting you cutter out of it. Once the cutter is lifted out it's extremely difficult to line up your cutter with the exact end of the score to resume cutting.







The things I've told you here should make cutting stained glass much easier. They are mostly things I've learned the hard way. I don't want it to be hard for you. So, just keep practicing what I've told you until glass cutting becomes second nature to you...AND IT WILL!


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This page was last updated on March 5, 2016