Enhance efficiency and convenience with scientific glass blowing supplies from DWK.
At DWK, we understand that, despite our extensive catalog, some scientific endeavors require custom glassware created by your own scientific glassblowers. To enable these efforts, we offer a broad range of scientific glass blowing supplies, including flanges, blanks for lids and vessels, stirrer shafts, bearings, and other essential tools for manufacturing customer-specific pilot plants, bioreactors, wiped film evaporators, or distillation apparatus. These scientific glass blowing supplies include blanks, such as separating or dropping funnels and evaporating flasks, which are ideal for master glassblowers who would like a grease-free operational experience.
Frequently Asked Questions
Glass blowers use many different materials which include glass that offers high resistance to thermal expansion and chemical corrosion, a furnace as the heating source, and protective equipment for safety. Other common glass blowing supplies include:
- Blanks as the starting material to craft custom glassware
- Hollow glassware with an empty interior space to provide containment for liquids and gasses
- Joints, closures, and connectors for securing connections
- Reaction vessel components which help to facilitate chemical reactions
- Sintered glass filters carry out filtration processes and ensure that no additional stress occurs when a filter is fused to a tube
- Stopcocks and valves to regulate the flow of gas or liquid
Hand-blown glass, custom-made by a scientific glass blower, is most suited when standard scientific glassware does not meet specific requirements. With hand-blown glass products, scientific glass blowers can modify standard scientific glassware or create bespoke designs to satisfy the unique needs of the research.
It’s important to understand that roughness cannot be defined by the grain size used in the grinding process. Parameters like the rotational speed, the grinding fluid used, and the contact pressure impact the resulting surface properties. For this reason, the requirements for surface quality according to international standards and our specifications refer to the arithmetical roughness of the surface (Ra).
DWK Life Sciences uses various methods for grinding — including diamond tools, silicon carbide, manual operations, and fully automated processes, depending on the type of product, the lot size, and the requirements.
First, a word of caution: broken glass is sharp-edged, and there is always a risk of injuries, even for experts.
To safely disconnect wedged joints, ask a colleague for help. Carefully pull the cone and the socket apart — no excessive force, as the glass may break at any time. While pulling, ask your colleague to shatter the joint by tapping on one of the tubes beside the connection. Use something similar to a ball-peen, made of wood or plastic — not metal — and be very cautious. If possible, turn the connection and tap from all sides. If there is no space to tap on one of the tubes, consider tapping on the joint. In this case, you have to be even more careful. Do not increase the force when the joints do not disconnect. Successfully separating a frozen joint is a matter of finesse, not strength.
Take a look at the question and answer below about avoiding “frozen joints” to learn how to avoid this situation going forward.
Here are some general guidelines to avoid “frozen” joints:
- Always use either vacuum grease or PTFE sleeves.
- Disconnect all joints when the apparatus is not in use.
- Never put a cold cone in a hot socket.
- Ensure the joints stay lubricated when working with fat solvent.
- Remember that wet joints tend to stick, particularly when wetted by alkaline solutions.
You can minimize leakage and secure an excellent efficacy rate through meticulous handling and optimizing certain factors despite challenges in attaining a 100% tight seal. These factors include the properties of the cone and socket, such as the joint’s roughness, taper's accuracy, and roundness. By focusing on these attributes, you can ensure a practical tightness, even in the most demanding conditions, promoting longer-lasting and more reliable use in incandescent lamps and neon tubes.
Appropriate usage of vacuum grease and the correct use of the retaining device are essential for achieving a minor leakage rate. For these reasons, the DIN-standard 12 256 (tightness test of conical joints and stopcocks) refers to unlubricated joints to make measurements comparable. The requirement for the leakage rate according to DIN 12 540 and 12 541 is: ≤ 0,1 mbar l/s -1 . While this is not a high-level value, the leakage rate of lubricated stopcocks is better by orders of magnitude. However, for the reasons stated above, it is impossible to give a universally valid specification of the leakage rate of lubricated stopcocks. Generally, we recommend using valves for requirements to the leakage rate ≤ 10 -3 mbar l/s -1 . For PRODURAN® valves, we guarantee a leakage rate ≤ 10 -6 mbar l/s -1.
KECK™ clips — which ensure a safe connection — are available for conical and spherical joints and are easy to attach and loosen. For even stronger connections, we recommend using safety joints. This type of connection offers a much higher retention force and provides a system to release “frozen” joints.
Note: Please consider that contrary to KECK™ clips, safety joints will not release overpressure. When using safety joints, you must ensure that your apparatus is either resistant to pressure or that you use a pressure relief valve.
Sizes of ground joints are generally specified by two numbers, separated by a forward slash.
The first number represents the ground area's largest diameter (mm). For many sizes, the nominal size is a shortcut for the real size, like NS 19 (stands for 18,8mm) or NS 29 (29,2mm). The second number stands for the projection of length of the ground zone.
Example: NS 14 / 23
largest diameter (d): 14,5 mm
length (l): 23,0 mm
smallest diameter 14,5 – 23/10 = 12,2 mm