How to clean a glass tube or glass.
 There are many ways to clean the glass of soot - let's look at the three most common ways :
 t hermic method
 m echanical method
 c hemical method
 The first method is one of the simplest. The glass is heated to a higher temperature, the soot burns away and the glass is thus clean. The temperature can be increased by adding charcoal dust to the fuel. But there is a great risk of overheating that and ultimately leads to cracking cracking.
 The second method is the most expensive . You need special devices, devices or aids such as the brushes for cleaning chimneys or drains and the physical exertion . This method is quite time consuming and cumbersome. There is also a risk that you accidentally put too much stress on the glass, causing it to break (the glass is a very brittle material).
 The easiest way is the 3rd method
 It requires a sealing plug, water and possibly H aushaltsreinigungsmittel.
 Put a plastic stopper on one end of the pipe and pour water up to the top.
 Add dish soap or just vinegar to speed up the process.
 And leave it there act a while. The soot will peel off the glass.
 We've only been using the third method lately.
 We have developed a special sealing plug that also serves as a holder.
 We use a 3D printer for production. The printer allows us to manufacture the parts in a high complexity, also can make in production, without wasting time and resources to waste w ir changes.
 The cap itself has a complicated structure. The inner surface has a wavy structure with a step of 2.5 cm and an amplitude of 1.8 mm. This allows for a closer fit on the pipe.
 The lower part of the plug has a larger area for better stability. The protrusions also serve to make it easier to remove the cap from the tube.
 The inside is not monolithic, but there are a number of planes that form triangles. This gives the stopper more elasticity.
 As you can see, it's not a simple polymer stuff !!!