In order to get a decent set of wine glasses for musical performance, what properties should I be on the lookout for? I've heard that the glasses will only be playable if they're pure crystal, but that's prohibitively expensive, and I'm hoping it's an exaggeration. However, I've never been able to get a pitch out of the wine glasses I have around. It's possible I don't understand the performance technique. So: specific materials, thicknesses, brands, techniques?
My experience is that thinner-walled wine glasses work better than thicker-walled; lead crystal better than plain glass; glasses with rims that are not the widest part of the glass (i.e. burgundy glasses better than martini glasses). Also, hard water seems to work better than soft water, and it's critical that the glass and fingers are free of grease/oils, and of detergent.
On most glass harps I’ve seen, mine included, brandy glasses have the most versatility meaning that you can find a wide range of notes for the same style of glass (4ozs to 29 ozs). Consistency in style and same glass manufacturer are key to a better sounding instrument. I’ve also used these glasses from low register to high: Red Wine, White, iced tea, water goblet, dessert wine, champagne flute, and cordial
Elaine O'Mara's research has some of the more comprehensible explanations of the qualities to look for in a singing glass and advice on technique:
In conclusion, I found that the pitch raises as the size of the glass decreases, lowers as more water is added to the glass, and also lowers as the thickness of the glass increases. I also found, in an unrelated experiment involving hot water and a tea bag, that heating the water (and consequently the glass) makes the glasses less inclined to squeak while they are being played.
As far as what drinking vessels to use, all my research indicates an ovverwhelming commonality: you need crystal glasses for this trick. The only source that suggested differently was L.J.F Herman's piece written for Leiden University that suggested a thin walled mug made of quality pottery could produce musical notes:
Just replace the glass by a mug that has a handle. If there is a choice, take a thin-walled mug made of good-quality pottery. Put it in front of you on the table with the handle towards you, pointing South, so to speak. Now take a spoon and tap. If you tap at the opposite side (North), or East or West, you produce a tone that is distinctly lower than if you tap at positions in between. This confirms that it is the fundamental vibration mode that we are exciting: it is the handle’s extra mass that makes the frequency lower if it is positioned on an antinode. Look at it as a simple variation on the harmonic oscillator theme, for which we remember the frequency to be determined by √ — (k/m), with k the force constant and m the mass.
It is important to check the sound of both near full and empty glass, determining the range you can tune it by changing the amount of water.
You may discover that the glass does not sound inside the range you need at all, that the sound is bad exactly near the tone you need to tune it, or that the tone difference between full and empty glass is less than the range requirement for your instrument. For such case you may need multiple types of glasses (small and big) rather than just using a single type.
The easiest way seems by using some sound analyzer to determine the tone. I have developed my instrument using Sygt. Red wine glasses tend to have lower tones. Beer bottles may sound very high.