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HOT GLASS COLOR SAMPLE SETS

We at C&R Loo have compiled an excellent sample set for Kugler and Q-Colors. These sample sets are available EXCLUSIVELY from C&R LOO as a service to our clients and are an invaluable tool for selecting colors. Please note that there may be slight variations from the sample to the actual color. The sample sets are made up of thin blown chips of each color. These chips have been numbered and are displayed in heavy duty slide sheets enclosed in a ring binder. Striking colors have NOT been re-heated and do not show the final colors. Zimmermann and Wiesenthal color charts are also included. Part no: G-SKU Price: $100.00. You may also view color charts on our web page at: CRLOO.COM.

COMPATIBILITY

In order to be compatible glass color rods must agree in coefficient of expansion, viscosity, and annealing range with
the base glass being used. Q-Colors, Kugler, Zimmermann rods are designed to have a similar coefficient of expansion
and viscosity and therefore are generally compatible with one another.

Rods with the same batch number will generally have the same rate of expansion. If you use a rod from a different batch, you should conduct another compatibility test.

Most of the color rods have a relatively high lead content which allows expansion of approximately 2-3 x 10-7 without danger of damaging results. The following list of colors are for technical reasons, produced free of lead and therefore require a very close tolerance level for off hand glass blowing:

Q-Colors: 20, 67, 68, 69, 77, 78, 121, 125, 134, 140, 141, 216.

Kugler: 20, 67, 68, 69, 77, 78, 121, 125, 130, 134, 140, 141, 216, and 220.

Zimmermann: 59, 82, 83, 681, 701, 774, 8512

CAUTION: ALL Q-COLORS, KUGLER, ZIMMERMANN AND WIESENTHAL PRODUCTS SHOULD BE TESTED FOR COMPATIBILITY WITH YOUR CULLET OR BATCH BEFORE PRODUCTION!

The ideal test for compatibility is the one that most closely simulates YOUR process of blowing glass.

For information on annealing and tempering, refer to  The Handbook of Glass Manufacture by Dr. Fay V. Tooley, Section 14 "Annealing and Tempering."

Check our web page for more information

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COMPATIBILITY TESTS

TEST 1: PULL TEST

Heat a 1/4" wafer of color in the glory hole on the end of a puntile rod and marver it out. Gather an equal amount  of your base glass. Place side by side and marver until they are fused together. Pull out into a thin cane. Break the cane into a 24" long section. If the two glasses differ in linear expansion, you will see that the cane has a small bend in it. The glass of greater linear expansion will be on the inside of the bend.  It is tricky to get consistent results from this test at first, but once you become more accustomed to it, it can be quite reliable and you will soon recognize a pattern in your results.

TEST 2: BALL TEST

Gather a tiny amount of color. Encase the color with clear glass. Anneal. Cut into the glass with a diamond saw. If the glass cracks violently, it is not compatible. If the glass does not crack, it is likely to be compatible.

TEST 3: POLARIZING FILTER TEST

This is a simple way of testing a variety of colors at one time. Blow out a rondel of your base glass. Heat up a small amount of each color you wish to test and apply it to the rondel. Snip and press so that a 1 inch button of the test color is fused to the rondel. Anneal. Sandwich the rondel in between 2 polarizing filters, hold it up to a strong light source and rotate the top filter until it darkens (filters available, see end of catalog). If the color is not compatible you will see a strong halo of light around the color. If there is only a small halo, you can probably use the color safely. It is recommended that only pieces with little or no halo be used in sandblasting or cutting and polishing.

Expansion Tables

PLEASE USE THESE COEFFICIENT OF EXPANSION NUMBERS WITH CAUTION

These COE numbers were originally intended to be used to compare PROJECTED relative changes in expansion of a given glass with changes in composition of the SAME or SIMILAR glasses to EACH OTHER. The numbers are used by glass formulators to PREDICT changes in expansion when making raw material changes and therefore CAN NOT BE USED TO DETERMINE COMPATIBILITY OF GLASS. The numbers are usually based on temperatures from 0 to 300 degrees C, and since the COE of a glass at 300 degrees C is different from the COE of the same glass at 500 degrees C, THE COE NUMBER SHOULD NOT BE USED AS A GUIDELINE FOR COMPATIBILITY.  The only way to determine what works for you is to use the glass and see what happens. In addition, COE's can be either MEASURED or CALCULATED. If the COE is calculated, there are several ways to calculate the COE of a particular glass. The calculated COE of a glass determined using one methodology can be different from the calculated COE of a glass using a different methodology. You need to know which methodology was used to calculate the COE.

The "fit" of a particular glass is a function of both viscosity (resistance to flow) and expansion (change in size as temperature changes). Expansion affects the compatibility below the strain point, viscosity affects compatibility from the strain point to the annealing point. Two different glasses can be compatible if the strain caused by the mismatch due to viscosity is canceled out by the strain caused by the mismatch in expansion. For example, if the viscosity differences result in tension between the two glasses and the expansion differences result in an equal amount of compression between
the two glasses, then two forces cancel each other out and the glasses are said to be "compatible" even though the COE's of the two glasses may be different. Also, two glasses with the same COE can be incompatible if the viscosities of the
two glasses are different.

One last word - in addition to the above, the temperature at which you work, the shape & size of the object you are making, and numerous other factors other than the COE of a glass will also affect compatibility. For example, many people commonly use "104 COE" Moretti together with "91 COE" Kugler or Q-Colors in glass work. You would not think that this works looking at the numbers, but it can.

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