Tuesday, May 10, 2011

Learn how to paint with glass frit, using this excellent tutorial!

My first adventures in glass were by way of the stained glass craft. Frit Flowers were created in approximately 1995 when I began fusing glass. It took many months of experimentation to achieve the lines, which mimic the lead lines of stained glass. Like so many things, once you know how to do something it is incredibly simple no matter how difficult the discovery process may have been.

My first thought was that I would sell Frit Flowers at craft fairs and such. But the ever-searching curious side of me tends to just move on to the next glass challenge, and I never really do make it to retail. So, I put the technique away thinking I'd get back to it some day.

Seems however, that there is a growing interest in "drawing" with glass as can be seen at the Fusion Headquarters and their Liquid Stringer line of products. Since I don't seem to be doing anything with the technique and it is more or less public domain I might as well share what I know about it.

Visit the Frit Flower Gallery to see finished examples. Unfortunately when we at Harrach Stained Glass followed this link we discovered that it is broken.

Materials Needed
Glass Frit and Powder
Cake Decorator
CMC Powder (Cellulose Gum)
Mixing Bowl
Stained Glass Pattern

Outline of Steps

1.      Create a design or find a pattern
2.      Cut glass to size (1/8 inch or thicker)
3.      Place glass over pattern
4.      Mix CMC powder, glass powder and water to a peanut butter consistency
5.      Load the cake decorator
6.      Trace out the design on the glass using the decorator
7.      Let dry (speed dry with fan or hair dryer)
8.      Fill in pattern with glass frit
9.      Fire according to defined schedule for size of sheet your using

Detailed Instructions

Step one is easy. You can get an endless supply of designs from stained glass suppliers. There are many pattern books available. You can use a copier to enlarge or a digital camera to shrink the images, and of course you can just draw your own cartoon.

Step two and three needs no discussion other than the base glass must be compatible to your frit and no less than 1/8 thick. Iridescent glass isn't the best choice for this technique unless it is on the shelf side during firing. Transparent glass works best so that you can see the pattern through the glass.

In step 4 you create the glass paste. CMC powder is used extensively in the food industry. It is a gum additive for thickening products. It has great properties for glass drawing such as:
·      Really sticks to glass well.
·      Can be stretched when applying so you get a thinner or thicker line depending on your needs.
·      Can be reused days after it is mixed. Just add a bit of water to thin it back to a good application consistency.
·      Does not have an application "pot life". You can work as slow as you want.
·      Does not run. If your consistency is correct it will not run or spread, and will leave a nice crisp line.
·      Burns off completely and leaves no telltale residue.

The mixing ratio is 9.5 tablespoons of water to 2.5 tablespoons of CMC to 13 tablespoons of glass power. This will make enough for approximately 12 8x10 designs.

You can test your consistency by placing a small amount of the paste into the cake decorator tip, then pressing lightly to force the paste out of the end of the tip. The line that you draw should stay firm and not spread out, and it should flow out of the tip with very little effort. If you have to force it, then you're too thick.

Step five is the true test where you load the decorator up and see if it flows out nicely. If you have to force it out, then unload the paste and add a few drops of water and repeat the tip test above. If it is too thin then add just a little more CMC, just a pinch or two depending on the size of your mix, and how thin it happened to be. CMC comes in several sizes. I ordered a small bag from Axner Pottery Supply.

Tracing out the design in step six is a breeze if the mix is correct. Play with the stickiness and elasticity of the paste to your advantage when drawing. It might be tough getting real fine detail. If you used a #1 decorator tip and the mix was just right you might be able to get the detail in the Sun's face for example. A #2 tip was used in the examples.

When drying in step seven you can clean up the lines. If they are not quite right or got fat in a few places you can push them around a little while still wet. If you wait until the lines are completely dried, then you can actually carve the lines to make them thinner or more flowing and elegant.

Taking carving to another level, you could actually put paste all over the whole piece of glass and carve out a design!

Step eight is completely open. Have fun, it is just like a coloring book. Here are some examples of the FritFlowers before firing.

The firing step doesn't have any special instructions. It should be fired just like any other project. The schedule I use is:


Like any firing schedule this is just a guideline. I ramp by 610 an hour and hold for 4 minutes at 1225 degrees F. Then ramp at full power to 1500 and hold for twenty minutes. I look at the glass at during this segment and as soon as the glass has fully fused flat I crash the kiln to 960 F. I don't usually need to stay at 1500 for the full 20 minutes. From 960 I bring the kiln down 200 per hour to 600 degrees, and then turn off the kiln and let it come down to room temp.

The following are some questions from visitors of this page.

I'm very excited to try your frit flowers, but have a couple questions. I ordered the CMC powder and understand how to make the lines, but when it comes to the "coloring" part of filling in the lines:
What size frit does one use?
 Is it dry, mixed with water, or mixed with the cmc powder?
I'm just starting out so I don't have tons of frit, but I do have 6 or 8 colors of powdered glass and a 40 pound bucket of a larger size (not powder, but not huge) clear. Could I mix the clear with the powders to do the "coloring" with?

To answer the questions...
FRIT SIZE - Any size of any compatible glass frit will work (compatible with your base glass also, of course). The outcome will be different depending on what frit sizes and what frit combinations you try. There is no best combination. It it up to your personnel taste. One good combination is a #2 or #3 frit of light value like transparent yellow, and then sift over top of that frit by adding a dark valued transparent powder like orange. The orange will fall between the cracks of the frit, yielding a nice value/hue changing pattern. Instead of transparent orange try an opaque white or orange or all three.
Before mixing your colors you MUST do color tests first. The colors you choose might just turn to 'mud' when fused. If you don't have the patience to color test, then buy Bullseye's color mix chart. A quick way to test is just to make a bead of your chosen glasses using a torch. If you like the mix, then it will probably make a good FritFlower.

Don't forget that you can really kick-up your design potential by mixing the opaque powders to form new colors that are not in the Bullseye color palette. 

You might have seen this on my "about fusing" page. http://jimbolesdesigns.com/aboutFusedGlass.htm
Unfortunately, Harrach Stained Glass checked out this link and it is no longer working!

FILLING IN THE COLOR - You don't need to use frit at all. You could use all powders. If you did this then it is best to "wet pack" the powder once in place. That is, apply it by "drizzling" it in place with your finger tips, or, to be more precise load up a decorator with powder, and then tap the decorator when the tip is over the area to be colored. The powder will fall neatly from the decorator into place. (Wear a mask). You will then mist the finished piece with thinned Fuser's or Pate glue and push gently down on the design so that the colored powder joins up nicely (bonds) with the black lines.

When applying dry powders only (no frit used) wet packing is required because the powders ball-up towards the center during fusing, and move away from the lines, leaving the areas next to the lines with little to no color. This however, could be a nice effect if you want to do a second firing and only tint the more clear areas with another color.

I have never used the decorator to apply the powder colors wet, but I think someone should try this and let us know how it works. I think this is actually a good idea and may make the whole process more production ready. If the powder were mixed with the CMC to the same consistency, then you would apply the color the same way as you do the lines. It would be a very neat (i.e. tidy) method and would be wet packed without the spaying step. For production purposes, you would have a decorator dedicated to each color, and store them all in a container in a refrigerator when not in use. I'm guessing that you could pull them out of the frig a week or so later and make another batch.

Using just clear frit and powders will work, but I would suggest "drizzling" or sifting onto the base glass before adding the frit, and then after adding the frit add more powder (on top of the frit), insuring good color saturation. Both transparent and opaque powders work fine and form a nice mottle pattern around #3 sized frit when it melts down. It is good to mix similar hues both for color gradations and for color compatibility. This avoids mud-like mixtures, resulting from the chemical reactions between colors that don't "like" to mix well.

Wet Packing

I've added the following information on wet packing to help clarify ongoing questions. The following pictures show the two sides of a test piece. The lines where drawn and powder added as typical. However after the powder was in place the whole piece of work was misted with a mixture of fusing glue and water. This compacts the powder. You can then add more powder once compacted to the level of the lines which were drawn with the decorator.

For this test I was working in reverse. I wanted  the ending design to show from the "shelf side" of the firing. This results in a matt or eggshell type surface from the texture of the fiber paper on the shelf. The process was as follows:
·      After the lines where drawn on the glass I filled in with power, wet packed, and added more powder, and wet packed again.

·       I then topped off the design by sprinkling a bit of #1 black frit along the lines so that the lines were not as distinct, then set to dry.

·      What was the top of the design was then placed on the self face or top down, resulting in the textured surface seen in the picture on the right.

Working with glass paste in this manner is very much like working in the technique of Pate De Verre. There has been a lot published on this very old glass technique so I won't ramble on here. I just wanted to give some examples of wet packed powders, and to emphasize that this process is necessary when working with a powders-only design, and you want the powder to remain true to your outline. By its nature powder will gather "away" from the drawn lines when fired, and concentrate itself in the center of a design area. This results in clear areas next to your lines. This can be a nice effect, but probably not what you were looking for.

As mentioned in the Q&A above, instead of applying powders and wet packing, it could be far easier to just apply all of your colors as a paste via the cake decorator. It would just depend on what you are after. Applying the colors dry enables a very controlled color mixing. Alternatively, you could mix colors in paste and apply by hand, repeatedly mixing in new colors to achieve very subtle color gradations. If these techniques of glass working intrigue you, and you  haven't done research into pate de verre, then a whole world of literature is waiting for you.

Fusion Headquarters Liquid Stringer Medium (LSM) Product

I have recently tested the product and I was very pleased with it. I mixed mine a with a little less water than instructed, and used a #2 cake decorator and the results were just fine. You might even be able to go as low as a #1 size. CMC lines when dried are fairly tough and can be reshaped a bit. Liquid Stringer lines where too fragile to be manipulated after they are dried.

For production work I'm not sure how the Liquid Stringer paste would hold up to storage and reuse. I just haven't used it enough yet. I suspect it might be OK. Overall I was very pleased with the product and would recommend anyone to try it.

The following is a image provided by Gil Reynolds of Fusion Headquarters. In this piece LSM was mixed forming a paste for the three colors in the design. The paste was applied in rows on a sheet of glass. While the the paste was still wet it was combed in the same fashion as is often done to hot glass. This is a great twist on glass combing. Cold combing is much more controllable, and not to mention safer than reaching into a 1500-1600 degree kiln to do it hot.

The following are some comments provided by Gil

"... if you mix LSM and frit with no water 1 to 1, you will find that the lines are very workable when dry. This mix is not as brittle and hard as the CMC mix. It is really cool to mix 2 frit to 1 LSM, form it into a mound or block, let it air dry completely and then carve. It is so friendly to the tools, yet it holds up really nice."

This is an excellent tutorial that Harrach Stained Glass came across a couple of years ago.  We do not know who wrote it, and we forgot to save the author's name and information.  So if any of our readers know who is the author of this great tut, please send us a message so that we can give them the recognition that they so justly deserve!

We believe that the author of this tutorial is Jim Boles: 

http://www.jimbolesdesigns.com/flash/splashPage/splashPage.html ,   
http://jimbolesdesigns.blogspot.com/ , 
and http://havekilnwilltravel.blogspot.com/
check out his glass art, it is beautiful!


  1. The corrected link is:

  2. Thanks Jim for your updated web site address. We hope you get some traffic to your page through our blog and that you get some sales from our readers! We are loving your work!


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