Glass Shop Tips

	UNIVERSITY of DELAWARE
	DEPARTMENT of CHEMISTRY and BIOCHEMISTRY

*Glass Shop Tips*
(I will add new items occasionally)


OOPS!! Can my glassware be repaired??
The answer depends simply on where the break happens to be, the extent of the damage and cost of glassware. Is it worth it to repair something like a test tube or basic pipette? Not usually. However many items (sometimes very expensive) are thrown away because someone feels it is unrepairable when in fact it can be "saved". If in doubt bring the item to the Glass Shop for a quick evaluation. I will be able to tell you the likelihood of repairing it, whether it is worth repairing, and to give you an estimated completion date. Remember...the Glass Shop is here to help you. Don't hide or throw away damaged glassware because eventually you or someone else will need it again. This can cause an emergency for everyone (including me!) that could have been easily avoided. In some cases, depending on damage assessment, I may ask how apparatus was broken. This is only so I can consider whether a different design or modification may be stronger for your particular application. "It really doesn't matter to me who broke it". Bring it down to the shop so we can help keep your groups' research flowing smoothly.
Stuck Stoppers, Joints and Stopcocks
1.While holding "close" to ground portion , try rocking while pulling and turning gently, Turn stuck joints 90 degrees and repeat. Try this 5 or 6 times. 2. Heat “quickly” with heat gun or "soft" flame (if no solvent or other flammables are present) and repeat above. If heated correctly the outer joint will expand away from the inner in about 10 seconds allowing removal. If heated too slowly or overheated the inner joint will expand also and you must let it cool completely before repeating. Joints or glassware that has been heated above 490c should be brought to the Glass Shop for lehr annealing as soon as possible to prevent breakage. 3. If all fails, or if you are unsure about the above suggestions, bring it to Glass Shop for removal or demonstration. As always...wear eye protection! Usually frequent "greasing" will prevent this problem. If you cannot use *grease in your particular application it is best to use a teflon sleeve to prevent sticking.*
"External" Stress relief of vacuum system
When you clamp a vacuum manifold or attached vessels, be sure you tighten with even pressure from both arms of the clamp. This will prevent a torquing of the glassware and unexpected breakage from occurring.
Removing rubber tubing from apparatus.
When pulling hoses off of glass hose barbs attached to glassware, hold as close as possible. If it does not slide off easily you should slice tubing with a razor. This will help prevent hose barbs from being snapped off.
Tightening ultra tore fittings
When tightening an ”ultra tore” o-ring type fitting, be sure that glass tube is not bottoming out in the metal fitting. If it is left touching the metal seat it can chip or break during use. Insert tube fully and "loosely snug" the fitting. Then pull the tube 1/4" away from the bottom before the final tightening.

Toepler Pump, mercury diffusion pump or other glassware containing mercury
It is always wise to place your pump or mercury containing glassware inside of a plastic vessel in case of breakage. A cut off nalgene, bleach or other proper size readily available container works great.

Importance of vacuum stopcock maintenance
I realize that no one wants to stop to clean and re-grease glass hi-vac stopcocks. However as you all know, after you open and close valve repeatedly it becomes harder and harder to turn. This will eventually lead to a leak or breaking off the entire stopcock from your manifold. This will happen even faster if you warm with a heat gun. Make the time to keep your system running smoothly, or next time try using a new style teflon hi-vac stopcock.

What type of glass is it??

Although a true test to determine glass type is difficult at times, I have a few suggestions for making a fast logical guess. Most glasses used in research are of 3 "basic" types:

Pyrex/ Borosilicate- If you look at the ends of the tube they will usually appear light to medium green.

Quartz/ Vycor- Ends will appear white.

Soda lime, Flint or other Soft glass- Ends will usually be dark green, or any shade of blue.

Be aware that if the glassware is graduated or has color decals, the ends will possibly show that color (especially blue) giving a false indication of glass type.

If you need it tested further or require a compatability test.... bring items to the Glass Shop.

Cutting Flat (Plate) Glass

Scoring/Scratch Method

Cutting flat plate glass may be easier if you follow these tips. Always wear protective eyeware and gloves!

Typical flat glass cutting tools: Wheel (or diamond type) cutters. Cut running pliers (if needed)

1. Be sure your scratch (score) mark goes to both edges of the plate (and make only one scratch). Multiple scratches can cause a bad cut.

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.

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 side of 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 under score mark(score should be facing up). Wet score. Holding each end, press down until it breaks cleanly.

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.

Feel free to come to the glass shop for a demonstration.

Snapping Glass Tubing

To cut glass tubing you need a "sharp", triangular file or a glass scoring knife. Place the tubing on a hard, firm surface, hold firmly with one hand and mark a scratch with the file where the tube is to be broken. You need to press with the file and you can hear it cut the surface, leaving a white mark. For small diameter tubing (under 10mm) you only need a small scratch.

Wet this scratch with a little saliva or water, turn the tube so the scratch is facing you. Grab tubing with thumbs on either side of scratch. Bend (elbows pushing away from you) while pulling the tubing lengthwise to open up the scratch. You should be pulling apart more than bending for best results. NOTE: If you just push elbows away from you and bend tubing it will chip or break badly. For a larger tubing (10mm-30mm od) you may need to make a slightly longer scratch first. Practice and you will find it easy to get a nice break in no time. I like to firecut or saw tubing above 30mm for best results.

The potential to get cut is greater snapping tubing as opposed to cutting plate glass. I suggest you come to the glass shop for a demonstration before trying for the first time.

For extra safety hold the tubing in a cloth or wear cut proof gloves.

Basic Glass Making Formulas
The following was provided for entertainment or educational reference only. Some of the ingredients may be harmful to you or the environment, especially when heated. The actual process (as well as safety information) should be researched fully before ever attempting to "make" glass. If you require further information please contact the glass shop. There are literally hundreds of glass types and variations attainable. Below are just a few of them.
	Clear Plate Glass Quartz Sand 100 Lime 12 Soda Ash 33 Iron Oxide 1.92 Potash (refined) 6 Manganese .5 Saltpetre 2	Green Bottle Glass Quartz Sand 100 Lime 34 Charcoal 5 Salt Cake 38	Optical Glass Sand 100 Lead 67 Potash 30 Saltpetre 3-1/3
	Semi White Plate Glass Quartz Sand 100 Lime 26 Charcoal 4 Salt Cake 26	Amber Bottle Glass Quartz Sand 100 Lime 38 Cannel Coal 14 Charcoal 8 Salt Cake 40	Lime Flint Glass Sand 100 Potash 35 Burned Lime 19 Nitre 1.25 Green Nickel Carbonate .007 Cullet 100
	Gold Red Glass - 600 lb batch Measured by weight instead of parts. Sand 62 lbs Lead 76 lbs Nitre 22 lbs Antimony 6 oz Manganese 3 oz Gold 4 oz	Copper Red Glass Sand 100 Carbonate of Sodium 28 Slacked Lime 24 Lead 8 Cullet 100 Oxide of Copper 4 Oxide of Iron 4 Nitrate of Potassium 8	Cheap Blue Glass Sand 100 Soda 35 Lime 18 Cobalt 1 (oz) Nitre 7 Manganese 2.5 (oz) Arsenic 2.5 (oz)

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