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![]() Home Page --> Miscellaneous Glassblowing Tips and Tricks
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This page is a small collection of glassblowing "secrets" for the glassblower and technician. Many of these glassblowing tips and tricks have been used by scientific glassblowers for years in some form or another. Acknowledgment should be made to The American Scientific Glassblowers Society (ASGS) and its membership. The ASGS has provided via membership contributions to the journal FUSION, video tapes, seminars and symposia the foundation for some of the information presented here:
Also see our Home Page for tips and info that merit an entire page of their own.
Annealing scientific glassware is necessary for practical and safety reasons, and all your work needs to be properly annealed to remove glass stress prior to handing it over to your customers. For those who are getting started with a home shop and do not have immediate access to proper annealing oven, you may find this tip helpful:
Use a kerosene heater as a "temporary annealer". The heater I had used was about the size of a 5 gallon can and was the sole source of heat in the unfinished New England garage where I had my shop. I've placed newly fabricated, water -jacketed flasks with multi-ring seals on top of the kerosene heater to hold until I had a batch of glassware ready for transport to an oven 6 miles away for proper annealing. The heater serves as a transition stage to cooler temperatures, yet produces enough heat to protect the glassware from cold drafts, preventing possible thermal shocks. Note: Be sure you have adequate ventilation when using kerosene heaters.
The Corning Museum of Glass has a web page with an excellent video that demonstrates stress in unannealed and properly annealed objects.
Cutting flat plate glass may be easier if you follow these tips. Always wear protective eyeware and gloves!
![]() Typical flat glass cutting tools. Photo Credit: The Fletcher Terry Company |
1. Be sure at least one end of your scratch or score goes to the edge of the plate. Line (a) will not break as cleanly as lines (b) and (c). 2. Curved lines can be produced and cut as well. Make one good score by applying even pressure on the glass with the cutting tool. Repeated scoring will not make the glass break easier or produce a clean cut. 3. Wet the scratch with water (a spray bottle will work fine) just prior to breaking. If glass pliers are used, apply them at the edge where the scratch ends. If using the "tap" method, tap on the glass surface opposite the scratch. Start at the scratch end and follow or chase the break across the glass plate. |
4. An alternate way of breaking the glass plate is to place a very small diameter rod (c) under the glass plate opposite side of score (b). Wet the scratch. Holding end (a) firmly down, press down on end (d). If you are attempting to remove a strip of glass less than 25mm in width, it is recommended that glass pliers or the "tap" method be used. Cutting tools come in different forms and wheel angles. Wheel angle guidelines are 130-140° for window (float) glass and 88-114° for borosilicate glasses. |
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Fletcher-Terry Company has additional information on glass cutting wheels. Also check out their white paper, The Principles of Glass Cutting.
Holes in glass plate are traditionally cut using water cooled diamond core drills or metal cylinder "cookie cutters" used with an abrasive slurry. The following tool is an inexpensive way of cutting holes using a glass drill. This is also a good method to cut windows for sealing into glass tubing.
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Use the same slow speed as in using metal cookie cutters. Start glass drill contact slowly without much downward pressure. Allow for equal material loss from the glass drill as in the glass plate being drilled.
Quartz working characteristics are very different from those of borosilicate glasses. Quartz will not flow in the same manner as borosilicate glass, so a different approach may have to be taken when attempting certain seals.
Attaching quartz capillary of very small internal diameter (<1mm) to a larger quartz tube with minimal change in the capillary dimension can be difficult. The method below is one way to make this seal. The seal was developed to meet the need for numerous quartz nozzles that required a consistent non-tapered .75mm opening over a path length of 5 mm.
This seal can be used on borosilicate and other glasses as well.
Problem: A method to gather molten metal core samples from a pilot plant scale furnace was needed.
Solution: An evacuated quartz ampoule with thin "break away" bulb.
This type of sample collector can be easily modified by using other types of glass and methods of breaking glass bulb.
The "suck seals" shown below are a quick way to make a "T" seal on a piece of apparatus. Properly made, this seal is strong and durable. However, if you have the choice, the traditional way of making a "T"seal is the preferred method.
Step 1
Step 2
Step 3
The following method is a relatively inexpensive way to make small quantities of hard to find or special diameter quartz tubing. This method may also be used with borosilicate glasses. This procedure requires a lathe and vacuum pump.
Objective: 1/2" OD Quartz tube
Material needed: 10 mm ID x 13 mm OD quartz stock and a machined graphite rod 0.374" diameter
Disclaimer: Glassblowing has inherent hazards that can result in burns, cuts, injuries or even death. While every effort has been made to convey best safety practices, the materials presented herein can not anticipate every possible risk or hazard associated with a given glassblowing activity. The reader is responsibile for assessing and mitigating any and all such hazards or risks before commencing any activity connected with his or her use of these materials. Neither the author nor ILPI assumes responsibility or liability for injuries, losses, claims or damages to the reader or other parties that may result from the use or misuse of these materials.
by Joe Walas and/or ILPI, all rights reserved unless otherwise stated. Unauthorized duplication or posting on other web sites is expressly prohibited. Send suggestions and comments (include the URL if applicable) to us by email.