Seven indicators your rotary evaporation glassware is of good glass quality

Glassware is so common in the laboratory, that its importance is often overlooked. But the parts and accessories you use in rotary evaporation need to be of excellent glass quality if you want to maximize the efficiency of your process and protect your system longer. Here, I give you several important parameters that you can use to evaluate the glass quality of your own equipment.

It was my daughter’s birthday recently, so to mark the occasion, my wife organized a homemade wine tasting event for her and her husband. Now, my wife and I do enjoy the occasional glass of wine, but we are by no means experts. We had to read up a lot on how to become self-proclaimed wine tasters. During the actual birthday, we had a lot of fun twirling glasses, inspecting colours, sniffing scents and sucking in air through mouthfuls of wine to release the full flavours of the drink.

Funnily, as we prepared for the wine tasting event, we also read that the glass quality can influence wine flavor. Unsurprisingly, my thoughts directly leaned towards glass quality of equipment needed during rotary evaporation. And just like many points exist to suggest a wine is of good quality, we also have many parameters that indicate the glass quality of your laboratory evaporation equipment.

I would toast to glassware with superior glass quality any day. But how can you judge if your equipment is of high standards? Well, let us take a look at seven indicators of glass quality that I’ve assembled for you.

The joint of the evaporation flask
You should care about this parameter, because a tight joint helps maintain vacuum stability and can protect you from potentially hazardous fumes. To test the glass quality of your evaporation flask joint, pour some ethanol into the neck of the glass, place the vapor duct inside and move it around. If your glass is of good quality, there should be no bubbles between flask and vapor duct. You shouldn’t be able to move the vapor duct at all thanks to the tight fit.

The shape of the evaporation flask
Inspect the shape of your evaporation flask. If the flask is very round, it is less likely to wobble. The wobbling effect is important because wobbling flasks drastically reduce seal life, resulting in more costs and waste.

The stopcock
A good glass quality stopcock ensures the tightness of your system. In other words, no air leakage is possible. If this piece of equipment is of good glass quality, when you apply vacuum with a vacuum pump, no air should come through the stopcock.

Wall thickness of your evaporation flask
Optimal wall thickness is essential for efficient heat transmission when using your rotary evaporator. Importantly, the evaporation flask should be uniform in its thickness.

Material of the evaporation flask
High glass quality requires use of high-quality materials. The material making up your evaporation flask should be highly resistant to acids, alkalis and organic substances. The material should also be resistant to thermal shocks and high temperatures with minimal thermal expansion. Suitable material includes DURAN® borosilicate glass 3.3, which is well known for its excellent temperature stability.

Combination of glass with plastic coating
Protecting your lab equipment of high glass quality can be achieved through use of plastic coating. In case of glass breakage, this plastic coating can protect you from contact with toxic chemicals, reduce risk of injuries due to contact with broken glass or glass splinter impacts. If you work with valuable substances, the plastic coating can help retain these substances in case of glass breakage. The plastic coating in itself substantially minimizes the risk of physical damage to your glassware.

The manufacturing process
If the manufacturing process is performed well and every step is followed thoroughly, the resulting glass quality will also be high. This means, the resulting glass is resistant to tensions, vacuum, mechanical damage and temperature stresses. Quality is further guaranteed by experience and companies such as BUCHI, with roots in glassblowing, are better poised to provide superior glass quality.

Take a look at how glass with stress looks like below:

rotary evaporation, laboratory evaporation, glass stress, glass quality

Compared to glass without stress:

glassware, glass quality, rotary evaporation, laboratory evaporation

If you’ve had enough reading at the point, but are still curious about the topic of glass quality, take a look at a short video on the subject:

Back to my daughter’s birthday, I didn’t even get into all the cheeses we had along with the wine! I think this is simply a topic for a future blog post! But coincidentally, this is not the first time drinking with my daughter has inspired a blog post. Check out what her milkshakes had to do with evaporation flask thickness in my previous blog post. Enjoy and cheers!

Till next time,

The Signature of Bart Denoulet at Bart's Blog