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It really depends on what you are distilling and how fast you want to do it. A Liebig isn't great for low boiling substances like methylene chloride, diethyl ether and the likes. But substances like ethanol and water and higher boiling points, condense reasonably fast, and a Liebig does a pretty good job. So a slight restriction of the bore will lower the surface area a bit and slow down the rate at which you can collect the distillate. Variables like coolant temperature are going to make a difference, and so is the enthalpy of vaporisation of the distillate, so it's hard to say whether this small change is worth worrying about without knowing all the detail. Give it a go and if it's not condensing fast enough, remove some heat from the boiling flask and just go a bit slower is the best answer.

Thanks for the question, it's a good one. Breaks occurring from large temperature changes are indeed a problem, but whole video is about spreading the heat over the entire piece using a bunsen flame and why it matters. A bunsen flame isn't too hot, and so to cool down from that temperature is not a problem for borosilicate glass. The temperature difference between the flame from an oxy torch and the temperature of glass in the bunsen flame isn't as wide as if the piece was at room temperature and so the stress is also going to be as bad either. In fact, cooling the piece down from the bunsen after the repair showed no stress at all with the polariscope. I demonstrated that this is a realistic approach to small repairs. Larger repairs with thicker wall glass and joins going through the wall cause more issues, and more care and specific pre-heating regimes are needed. And even then, with all the skill you have as a professional glassblower, it can still crack on you. An annealing kiln is absolutely necessary to take out residual stress after a complex repair. But if you come to understand how spreading heat over a larger area than just the point of the crack or repair work will prevent cracking , then you will progress your glass blowing skills and become more confident tackling more complex work. I hope that's what these videos are about.

I'm happy to hear you gained the confidence to give it a go. And even got a win from it. I'm going to try and put more content up for beginners soon. Any suggestions for new videos are always welcome. Thanks for commenting.

I don't think there'd be enough heat in a candle flame. Give it a go and let us know how you got on. Sometimes suck it and see is the best way to learn.

Thanks for watching and reaching out. I've got a small hand torch which runs off propane and oxygen, they are used by jewellers and some other crafts. But a small brazing torch for plumbing can also be used, so long as it runs on oxy/fuel and has a small enough tip.

"Smith mini-torch" he said in the video.

Hi and thanks for commenting. It's a fair point you make. I think I'm in the zone that many early content creators get into. We just want to get the info out there, and getting a video together is hard, editing is also really time consuming and has a learning curve all of it's own. So I'll own my early cringey work with it's unpolished edges, and I'll strive to get better with future projects. If there's some techniques or glassblowing details that need a deeper dive that others might have missed, let me know.

Flame cracking. Yes it's my preferred technique for cutting glass tubing. Make a score on the glass using carbide. Ive found router blades or boring bars for metal lathes a great tool for this job. Then turn the glass so the score is facing you with the tube in both hands. Come from under the flame, a small sharp flame, and touch the glass ahead of the score that is away from you with the flame that is very close to the tip of the torch. Rotate the glass so the flame just touching the glass creeps towards the scoreline. With the right amount of heat and the right speed of rotation it will crack reliably around the glass. Cold glass makes a less precise cut, the glass is brittle and the crack wants to find the path of least resistance. So using the warm air above the flame you rotate the glass where you want the crack to go. It should be not much warmer than body temp. Give the glass a few seconds to allow the heat to penetrate to the inside of the glass. Then use the technique described to cut the tube. Practise practice practise.

It's just a standard design Bunsen burner. Nothing unique about it.

I think it's David Moufang. Otherwise known as Move D. It's probably this recording: ruclips.net/video/ILDuFIjDfLs/видео.html

The bunsen says natural gas on it's base, but I run it on propane and it's fine.

Thank you 🙏🏼

Fuel gas and air through the venturi effect

Glass taps seal better that's for sure. But they are prone to getting stuck. Researchers and students can often break a tap trying to get it free. So there are quite a few people who order the PTFE taps for practical reasons.

Well spotted, I did suck and blow a few times, small in and out puff and suck. It helps form the shape of the internal seal which I go on to explain is critical to prevent it cracking. Although I just realised the upload chopped the bottom off the illustration I did as an explanation.

@@platinumlaboratoryservices8176 Makes perfect sense. Thank you. The important bits of your illustration were pretty clear. Very impressed by how uncluttered your work area is and noticed you put away every tool after each use (looks like to dedicated spots). One surprise was how you used the flame to detach the cold seal. Will have to give that a try instead of knocking it off.

It's a blowhose, to give pressure inside the glass tubes, in this case to blow a hole in the tube as you can see at minute 1:05.

Very True! The monitor does work, the stress will show as black and white bands unless you place a sheet of something like clear polycarbonate in front of the monitor. Thanks for your reply.