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Frequently Asked Questions
INSTRUCTIONAL
I am interested in doing some glass projects, but I learn best by seeing the process take place. Do you offer videos of fusing/ slumping?
The Bisque Imports Warm Glass Training Guide is an outstanding resource. This guide provides the information that you need to begin glass fusing and slumping. We also carry Contemporary Warm Glass by Brad Walker (Item # SR-205). It provides a fantastic education on glass fusing from one of the foremost glass authorities in the industry.
PLANNING & DESIGN
When beginning a project, do you start by fusing the desired design together then slumping into the mold?
Yes, you need to fuse the glass together prior to doing a slump firing. Glass fusing is the process of joining two or more pieces of glass together by applying the heat of a kiln. If you try to slump and fuse at the same time the elements of your project will slide in the slump and not retain their original shape.
Does glass always melt to the 1/4" thickness or does it depend on how many layers of glass you're trying to fuse?
Glass naturally wants to be ¼” thick (two-layers). Our glass components are 1/8” thick so when you create your two layers your project will be ¼” thick. If you use more than two layers of glass the project will expand until it becomes two layers. If you do less than two layers it will shrink until it becomes two layers. A hole can also form in the piece if the base is not covered w/ a full second layer. These rules are primarily important in a full fuse firing.
Does my project always have to be comprised of two layers of glass?
If you are doing a Contour Fuse or Tack Fuse you can create a project with a base layer and decorative layer that does not fully cover the base. In a Tack Fuse the glass retains its pre-fired dimension but still sticks together. A Contour Fuse results in a piece that has rounded edges but retains some of its dimension.
If I want to "draw" a design such as green swirl on a red bowl would I use a round blank and glass powder to draw it in like sand art?
You can draw onto the glass with a Sharpie and it will burn off during the firing. Apply glue on the glass and fill it in with frit to keep the design where you want it or design it like a mosaic with small bits of glass. You can also use Glass Multipens which are writer-tipped bottles of liquid glass that may be used to create designs on glass prior to firing.
Does glue have to be dry prior to firing?
Wait just until tacky - heat of kiln with help dry glue. Firing a piece while the glue is still wet defeats the purpose of using glue.
What happens if I use too much glue?
Using too much glue can cause a dark residue on your piece. To keep from getting this residue, apply glue sparingly, but enough to hold your pieces to the base or use Klyr-Fire Glass Glue which is specifically designed for fusing glass.
How do I measure for a drape?
Measure the height of both sides plus the base of the mold to determine the optimal blank size to use in draping. It is good to always place fiber paper under your project when draping to keep glass from sticking to the kiln shelf. If you use a piece of glass that is larger than the optimal size, your piece will drape onto the shelf and develop a rim or puddle edge. For some this is a desired effect. Be sure to have fiber paper under this project as well doing a slump.
What is the difference between slumping and draping?
Slumping and Draping are processes in which glass is heated so that it takes the shape of a mold on which it is placed. In Slumping the glass goes into the mold while Draping takes place on the outside of a mold.
Sometimes I get large bubbles in my glass, particularly when I fuse two large pieces together. How can I avoid these bubbles?
Schedule a hold at 1100°F for approximately 30 minutes and then proceed with a slow firing schedule. Remember that all kilns are different and you may need to do several test firings to determine the proper hold time and temperature for your kiln. In addition, fusing on top of fiber paper instead of a kiln washed shelf will reduce the opportunity for bubbles to form.
I find that it is hard to score Opal Art and Spirit Glass in a straight line. What can I do?
Turn the glass over so that you are scoring on the solid colored side. The smoother surface will allow for easier scoring and breaking.
Can I create a project with three or four full layers?
Casting Rings may be used to create projects with multiple layers. Refer to page 14 in the Bisque Imports Warm Glass Training Guide for more information.
Does each person need a work surface?
While it is ideal to allow each person ample space to work, two people may share a work surface for cutting and assemble their project on a portable work surface such as a tile or a flat surface of sufficient size.
TOOLS & ACCESSORIES
How do I drill holes into a fused glass piece?
Drill a hole into glass using a diamond drill bit. The area to be drilled and drill bit should stay wet to avoid heat buildup and damage to the glass. One easy way is to immerse the piece into a shallow tray of water then gently drill into the glass.
How do I cut rods?
Use wheeled nippers to cut rods by placing the wheels on either side of the glass rod and squeezing gently.
What is the difference in breaking and grozing?
A Breaker Grozer tool provides two tools in one. Place flat-sided breaker jaw parallel to the score line on glass then lower handles to snap glass along the score. Use the curved grozing jaw upright to gently nibble away unwanted edges from the glass.
MOLDS
I have noticed my stainless steel Casting Rings and Floral Forms change color after firing? Does the color affect the firing?
Stainless steel molds may darken in color after firing. This color will not affect your glass.
Can I use a small glass blank (8”) in a mold that calls for a 10” blank?
Yes, the finished piece will have a different appearance based on the design of the mold.
Can I slump a circle blank into a square mold?
Glass should not extend more than ¼” on each side of the mold. Glass that is over this limit may seize to the mold making the glass impossible to remove without breaking the mold or the glass.
Why do I have to prime molds?
Primer is applied to keep the glass from sticking to the mold
Why can't you use regular kiln wash on the molds?
The consistency of glass kiln wash is finer that that of ceramic (regular) kiln wash. Thus, you have a smoother surface. Glass kiln wash is specifically designed for glass.
How often should I apply primer to my molds?
Please see the Mold Care Instructions on page 9 of the Bisque Imports Warm Glass Training Guide.
Why do I need to drill holes in bisque that I will use for slumping?
Holes are drilled into bisque to avoid cracking or uneven slumping. This allows air to release while the glass is slumping. Our molds are pre-drilled for ideal slumping.
Why do you not drill holes into the pods like the slump molds have? Some like the pyramid are very deep.
The pods are fusing molds so you do not need holes. The banner plates and tile molds are also fusing molds but you can make them into slump molds by drilling holes into them. Their shape will accommodate a slump -- the pods will not.
FIRING
Can I use any bisque as a slump mold?
The Bisque Imports Warm Glass catalog highlights bisque shapes that are idea or slumping. If you decide to try other shapes, please refer to Selecting Bisque for Slumping in our Warm Glass Training Guide.
What is the difference in a drape v. slump firing?
You can use the same firing for both processes.
Can I fire 96COE glass (System 96) and 90COE glass in the same kiln load?
Yes. However, be sure do not mix the glass in the same piece.
Can I slump bottles in the same kiln load as a System 96 firing?
Yes, but do not add S96 glass to the bottles as they are not compatible. You may wish to create glass designs and glue them onto the slumped bottle after firing. Fusing pebbles and rod dots together to create a flower is a good option.
Do I have to use Duraboard under casting rings?
It is ideal to use Duraboard while assembling your casting ring project to allow for ease of moving the project to the kiln.
At what temperature can I open the kiln?
Refer to Open the Kiln on page 6 in the Warm Glass Training Guide.
Can fiber paper be re-used? How many times?
The life of fiber paper varies from project to project. To extend the life place Thinfire between the Fiberfrax paper and the glass. This allows for a smooth surface plus easy clean-up of the Thinfire.
What is fire polishing?
Heating glass just enough to round the edges and give a shiny appearance – approximately 1300°F – 1400°F.
AFTER FIRING
How do you care for the finished piece? Is it dishwasher/oven/microwave safe?
Your glass project should be cared for as you would any other hand-crafted work of art. Hand-washing is recommended for a finished glass piece. Dishwashers, ovens and microwaves are not recommended.
Can I use regular sandpaper instead of the Diamond Sanding Block to smooth the edges and back of my fused glass project?
Regular sandpaper will not smooth the edges of glass.
Why are there different thicknesses of fiber paper? Do I need to adjust my firing temperature to accommodate the different thicknesses of fiber paper?
MISCELLANEOUS
How much space will glass take in my studio?
Refer to the article on our website titled Glass Fits in Studios of All Sizes.
What do I need to get started fusing glass in my studio?
Bisque Imports offers five start-up kits in varying sizes. Kits may be reviewed in our Warm Glass catalog and on in the Warm Glass section of our website.
How do I manage firing glass and bisque in my studio?
When adding glass to your studio, a firing schedule is essential. While contemporary studios fire many times throughout a week, a specific firing schedule is vital for completing customers’ projects in a timely manner. As your customers’ interest grows, you will find yourself adding additional firing days for both fusing and slumping. It may work well to fire glass on Monday and Tuesday since a large amount of glass projects are produced on the weekends. Glass provides great margins so be sure to give it due attention and firing time.
Are there some ready-made signs that I may use to promote glass in my studio?
You may download a flyer and postcard template from the Bisque Imports website. These are designed so that you may insert your logo and studio information and use them as signs, flyers, bag stuffers and mailers to promote this hot studio offering.
Can children work with glass? What ages are appropriate for use of frit?
Children as young as 7 have successfully created glass projects. Be sure to provide gloves and safety glasses for their use. Adult supervision is recommended.
Are Glass Multipens food safe?
Once the Multipens have been fired they are food safe.
ADVANCED FIRING
Would my fused glass project be durable enough to use as a sink bowl? Our Stainless Steel Casting Rings allow you to create a fused piece with multiple layers that are ideal for use as a sink. The ring acts as a dam so the glass does not expand since it is greater than two layers. Once the glass is fused, the piece is draped over a stainless steel bowl. A project guide is available on our website.
TROUBLESHOOTING
Fiberfrax paper leaves a bumpy surface on the bottom of my glass. Is there any way to avoid this?
Fiberfrax paper has both a smooth and a rough side. If the smooth side is not smooth enough, try placing Thinfire paper on top of the Fiberfrax paper or simply fire directly on Thinfire.
The edges of my glass are sharp after a full fuse. What am I doing wrong?
Sharp edges are generally caused by a firing that is too hot. Try reducing the hottest temperature in your firing program.
I have slumped into a bowl but the bottom is not flat. What can I do to fix this?
You may re-fire the piece but try increasing the temperature and the hold time at the hottest temperature in your firing program. Begin increasing in increments of 10° until you learn what works best in your kiln.
I did a tack fuse, but the glass looks like a full fuse. Why?
Your kiln may be firing too hot. Adjust your firing program temperatures particularly during the segment where the hottest temperature is reached.
Why are the edges jagged when I use frit in my projects?
Coarse frit can cause the edges of a piece to become jagged. Try using medium frit closer to the edges or adjust your firing temperature to a slightly higher level.
Why does primer stick to the back of my glass project?
This generally occurs when the primer has been over-used. Clean the mold as indicated in the Mold Care Instructions on page 9 in the Bisque Imports Warm Glass Training Guide and re-apply.
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