Frits and Powders

Using Northstar™ Frits and Powders 

The term “frit” refers to granular crushed glass. Soft glass frits have been available to glass artists for a long time in many colors and several different mesh sizes. Furnace working glassblowers and European-style lampworkers use frit regularly as a means of adding color to their work. Frit can also be used in such techniques as Pate De Verre and fusing. 7

We offer many of our borosilicate colors in powder and frit form.

  • Large frit: Coarse; approximately .055 inches or 1.397 mm.
  • Small frit: Finer, approximately .024 inches or .6096 mm.

These frits and powders have been formulated for use with Pyrex®, Duran®, Kimax®, Northstar™ or any other glass with a similar coefficient of thermal expansion (33). Using frits and powders provide the hot glass artist with a means of adding color and/or texture to a piece quickly and easily.

There is no “right way” or “wrong way” to utilize frit or powder. Experimentation will lead to discovering your own unique effects and subtle refinements of techniques.

The basic idea is to get the frit to stick to a target object. In order for this to occur the temperature of the object must be hot enough to be soft (at least on the surface of the glass). The hotter/softer the target object is, the more readily the frit will stick to it.

If the object has already been formed and slumping is not desirable it is better to heat the object just enough for the frit/powder to begin sticking (by preheating the frit in your oven, the target object can be slightly cooler and therefore less likely to slump).

Successive layers can then be built up if a heavy coating is desired. A light sprinkling of frit may be used as a subtle highlight of brightly colored dots or a substantial layer of color can be built up giving a more uniform or darker look.

Frit can be coated on the outside of solid or hollow objects. It can also be coated on the inside of hollow forms. Frit may be fused in completely or left partially raised for a surface texture. A sprinkling of frit may also be mixed into the body of a solid gather of glass, giving the entire gather color. NS-00 Clear frit may be added over a colored object for effect. Different colors may be mixed for a custom look.

Application 

After first heating the “target object” hot enough so that frit or powder will stick to it, here are some possibilities.

ROLL METHOD

Put the frit/powder into a bowl or on a plate and then roll or dip the target object into the frit/powder. The piece should be rotated for an even coating. Repeat as many times as necessary to achieve the desired effect.

SPRINKLE METHOD

Frit may be sprinkled over your object either with a spoon or with the fingers. When using this method it is wise to place a clean plate or container under the work area to collect any frit that does not stick (invariably, some frit will not adhere the first time). Remove the object from the flame before sprinkling frit.

Sprinkling directly through the flame is not recommended since the flame will blow some of the frit away. This is not only a waste of good frit but can cause a dust problem in your shop (see health precautions).

TUBE METHOD

Frit or powder can be fused to the inside of a hollow object by sprinkling it into a rotating tube. Using this method the frit/powder may be added either before or after the object has been heated. This method can also be used when applying frit to tubing in a glassblowing lathe.

ROD METHOD

A clear or colored rod may be heated (usually the tip, coated with frit (roll method), and then applied in the usual manner. This is a very quick and easy method of adding color.

Working In the Frit and Powder 

Once the desired amount of frit or powder has been deposited onto the object, use a relatively cool flame to fuse it in. Use a cool flame because the glass is in the form of small particles and, until they are mostly fused in, are little bumps on the surface of the glass, easily caught by the flame and super heated to a boil, which could cause a rough texture. A hot flame may be used but the object should be passed quickly through the flame so as to heat the frit more gradually.

Working in the tip of the flame can help. While some colors may vary slightly in appearance from rod to frit/powder, most will retain there working characteristics i.e. striking, oxidation/reduction.

CAUTION: AVOID EXPOSURE TO GLASS DUST. ALWAYS USE A DUST MASK AND EXHAUST HOOD WHEN HANDLING FRIT AND POWDER.

These notes are intended as a general guide. Individual results will vary depending upon many factors including type of gas used (i.e. propane or natural gas), type of torch used (surface or internal mix), type of annealing oven used (gas or electric), and the sequence of heating and cooling. Individual batches of color may vary slightly, as all the color is hand made.

Northstar® Borocolour® should come to you pre-labeled for easy identification. Please be sure to store your glass colors in a manner that allows you to identify which color you are using and which colors to reorder.

If you should experience a problem with any of our colors please e-mail or call technical support. We want to know what your experience is with our colors. Your feedback will help us to continually improve our products.

Experimentation is the key to diversity as well as the best way to master the use of Northstar® Borocolour® Borosilicate Color Glass.