How does glass blowing work?

We take a trip into a glass factory
23 September 2019

Interview with 

Ryan Wood, Glass Solutions


Phil stading in front of a flame used to make glass


When a chemist wants a giant test tube, or a Harry Potter movie wants some fancy-looking glassware for an apothecary scene, who do they turn to? The answer is often “Glass Solutions”, in Ely. And Phil Sansom’s been to see their technical lead Ryan Wood, and have a go himself...

Ryan - Okay so this is one of the largest items that we make, it’s a 50 litre vessel, 3 layers of glass. Chemical reactions will be going on in the inside and then there's two more jackets on the outside. One of them is to keep it to the correct temperature that it needs and a third jacket is just a vacuum jacket just so there's no heat loss.

Phil - This is obviously a long way from the big glass tubes that are the raw material that I just saw. Can you take me through how you get from that to this?

Ryan - There are lots of methods that we use, so we will take the cylinder glass out and put it in one of our lathes.

Phil - And a lathe, to clarify, what is that?

Ryan - So it's just a big machine that holds and then turns the glassware. The working temperature of glass is around 1,100 degrees. So we have to take up to around 1,100 degrees before we can start moving the glassware around.

Phil - What happens to the glass when you actually heat it up? What does it do to it?

Ryan - We just melt the glass, it makes it malleable, so we can move it and then soon as it goes under a certain temperature it stops moving. So we have to keep everything up to the right temperature and there's lots of other factors that we have to do.

You have to worry about stress, glass stress. When we work the glass it’s trying to pull itself apart. So we have to get that glass into an oven as quick as we can before it breaks. The glassware needs to go in an oven at 565 degrees.

Phil - So are you saying that if you don't get it in the oven in time while it's cooling down, it'll be under too much stress and it'll shatter?

Ryan - Yeah, so if we were to put this glass on the side as it's cooling down the glass will fall apart.

Phil - This oven process is called anealing and what's going on is that at 565 degrees you get microscopic flow in the glass, and that tiny amount of flow means that little points of stress within the structure of the glass get smoothed down. It's the final stage of a hard day's work here.

Ryan - All of the glassware that we do here is handmade. The lathes are the only machinery that we have and we need the lathes. Other than that everything is handheld. We have graphite rods that once the glassware’s warm, we'll use the graphite rods to move the glass around and we have other tools as well. On each of our lathes we have a series of different flames.

Phil - I can see some of the jets I think right now, yeah, they look so scary!

Ryan - So this is what we call a whistle jet, our largest one is called a pepper pot. It's a very very large flame. This hand torch here we have a flame that comes out of it, may be a 30 ml flame, propane and oxygen mix. So it's a very very very hot flame.

Phil - What that means is like a bright blue flame right in front of me?

Ryan - Yeah we can get a lot longer flame depends on what we do. We can get to two to three foot, it's very very noisy and very very hot.

Phil - I'm genuinely frightened. Where does the actual blowing come in?

Ryan - So if we want a round end in a tube, we’ll need to connect a pipe from our mouth through the lathe into the glassware, and then we will heat the glassware up and we’ll gently blow the glass into the shape. Virtually everything under 20 litres, we will blow the glass.

Phil - At this point, Ryan let me have a go. I was ready for this. How hard can it be? You just
heat one end of the tube then blow down the other.

Ryan - [noise] Heat this end, OK? [noise] So that is very thin.

Phil - It almost popped didn’t it?

Ryan -  So you can see how flexible glass can be. If you blow too hard it'll pop into a million pieces.

Phil - How did I do for a first time?

Ryan - Good...

Phil - So maybe it's harder than I thought. Ryan was struggling to say nice things about my attempt. So I decided to move on.

How hard is it to learn to make something this big? Because that's a big vessel?

Ryan - It's going to be an absolute minimum of five years of training to get to a certain level. To get up to this size vessel, it will take around 10 to 15 years. It's very hard to see and understand what the glass and predict what the glass is going to do, once you get it hot.

Phil - When you're learning, what do you think you're getting better at?
Ryan - It’s learning the process to joining two bits of glass together. When you join two bits together you need them to run what we call a running in process so we need to create one piece of glass, and that's very very hard.

Phil  - Do you get fewer and fewer of those burns as you get better?

Ryan - Not really. I'm 22-23 years in and I still get burned just as much as anybody.

Phil  - Do you make pieces for places other than scientific labs?

Ryan - No absolutely. So we've made a lot for the film industry. So some of our work has included the Harry Potter movies, the time turners in there and the lot of the cauldrons.

The latest ones has been the Beauty and the Beast movie, and we made the wine glasses and we made the cover that went over the rose.

Phil - What's the hardest thing to make?

Ryan - Probably these large reaction vessels just because of the sheer size, the sheer weight of it. It's not only that but you get the heat exhaustion. Scott who makes these, he will -  after he's joined the two jackets together - be covered in sweat, and then he will be absolutely tired from the heat.

Phil - It's a real art isn't it?

Ryan - It is a real art. So we do enjoy what we do just because we have a slightly artistic side. Some people do say it’s a dying art. However glass will always have a special place in the science market. It's an inert material. I think there’s always going to be a future for glass, if there's science there's glass.


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