FAQ – Frequently asked questions about SiLibeads® Glass Beads

SiLibeads® are distinguished above all by strictly controlled raw material quality, tightly defined tolerances, reproducible production and a product range optimised for specific applications. Compared to generic glass beads, they offer:

• Tighter tolerances on size and shape
• Specific glass compositions tailored to the application (e.g. borosilicate/soda-lime glass)
• Documented quality and batch consistency
• Targeted optimisation for industrial processes (grinding, filtration, pharmaceuticals, etc.)

Technical:

• High roundness and tight tolerances
• Glass chemistry tailored to each application
• Reproducible process performance
• Wide range of types to suit many industries

Economical:

• longer service life in the process (depending on the application)
• lower scrap rates thanks to consistent quality
• optimised process efficiency (e.g. grinding energy, filtration)
• lower process variability

The main differences between the types are:

• Manufacturing process (pressed, thermoformed, cast)
• Type of glass (soda-lime glass, borosilicate, aluminium borosilicate, etc.)
• Optimisation of use

Brief logic:

• P → high-precision universal ball (measurement, valves, pharmaceutical applications)
• M → versatile, mixing and grinding applications, filters, industrial
• S → cost-effective, standard grinding + retroreflection + blasting
• SL → low-alkali special grinding ball
• AIR → hollow balls (lightweight construction, insulation)
• SOLID → Micro glass beads (filler, structure, rheology)
• WATER → Filtration and well applications
• PHARMA → GMP-compliant, high-purity pharmaceutical applications

The selection is based on four main criteria:

• Process type (grinding, filtering, mixing, function)
• Chemical environment (pH, media, temperature)
• Mechanical stress (abrasion, shear forces)
• Purity / control requirements

→ In practice, the type is always defined by application + process parameters + material requirements.

As every application has different requirements, we are happy to help you choose the right solution. Please get in touch – together we will find the ideal SiLibeads® solution for your process.

SiLibeads® Glass Beads typically offer:

• lower material costs (depending on the type)
• defined, uniform geometry
• very good chemical inertness (depending on the type of glass)
• lower risk of contamination due to uniform surfaces
• good balance between abrasion and energy input

Ceramics, on the other hand, often have the advantage of extremely high wear resistance, whilst glass scores highly in terms of purity and process stability.

Typical areas of application:

• Pharmaceuticals & Biotechnology (insulin, vaccines, cell disruption)
• Paints & Coatings (wet grinding)
• Water treatment & well construction
• Food & packaging systems
• Aerosols & dispensers
• Filler and lightweight construction applications
• Optical / functional coatings

In addition, other or specialised applications are also possible. Please feel free to contact us with your specific requirements – we will help you find the right SiLibeads® solution for your process.

Through::

• clear product classification by application
• technical advice / application support
• data sheets with clearly defined operating limits
• project-specific approvals in critical sectors (e.g. pharmaceuticals)
• defined specification and testing processes at the customer’s site

We would be happy to help you choose the right type of SiLibeads®. Based on your application and process requirements, we will recommend the best solution – even for specialised or new applications.

SiLibeads® glass beads are available in a wide range of sizes – from very fine microbeads to larger beads measuring several centimetres, depending on the specific type and application.

• defined size ranges with narrow sieve and size fractions
• high roundness for consistent and reproducible processes
• various tolerances and surface finishes depending on the application

In addition, various special versions are available, e.g.:

• different types of glass (e.g. borosilicate or soda-lime glass)
• customised size distributions
• coloured variants
• grades suitable for pharmaceutical and food applications

Other sizes and special requirements are available on request. We would be happy to help you choose the right SiLibeads® solution for your application.

Consistency is ensured by a multi-stage quality system:

• Carefully selected raw materials
• Defined melting and shaping processes
• Continuous process monitoring
• Multi-stage screening and classification systems
• Statistical quality control (SPC)
• Documented batch traceability

The aim is to achieve a very high degree of reproducibility across all production batches.

Typical characteristics of glass beads:

• high surface hardness (depending on the type of glass)
• low abrasion when used correctly
• controlled fracture behaviour under extreme mechanical stress

Abrasion and fracture data are regularly determined and are available in technical data sheets.

SiLibeads® Glass Beads are:

• highly resistant to many acids and neutral media
• somewhat more sensitive to strong alkalis (particularly at high temperatures or when exposed for long periods)

Durability depends heavily on:

• Glass composition
• pH
• Temperature
• Duration of exposure

In most industrial applications, they are considered to be highly chemically stable.

Service life is determined not only theoretically but also in a practical manner by:

• Endurance tests under real process conditions (e.g. grinding tests, filter tests)
• Abrasion and wear measurements
• Comparison across defined operating cycles
• Backflush or stress tests (depending on the application)

The actual service life depends heavily on the area of application (e.g. wet grinding vs. filtration vs. pharmaceutical applications) and is therefore validated on a case-by-case basis.

For highly viscous systems, robust, abrasion-resistant glass beads with high density and a defined size distribution are typically used. The key factor is the combination of:

• sufficient energy transfer during grinding
• good pumping and circulation properties in the grinding chamber
• stable ball structure under high shear stress

The specific choice of model depends largely on the product’s viscosity, the hardness of the pigment and the desired fineness.

• Smaller beads: more contact points → finer dispersion, but lower individual impact energy
• Larger beads: higher impact energy → more efficient for coarse pre-crushing

As a general rule:
The bead size directly influences the relationship between energy input, batch size and achievable final fineness. We would be happy to assist you in selecting the appropriate SiLibeads® bead size for your process and application.

What are the optimal process parameters (speed, fill level, grinding time)?

• Speed: sufficiently high to ensure good movement, but below the critical overheating threshold
• Bead fill level: selected to ensure maximum contact probability whilst maintaining a stable flow
• Grinding time: dependent on the target particle size and product requirements

The exact values are usually determined during process scale-up or laboratory testing.

Contamination is prevented by:

• chemically inert grinding media (glass)
• very smooth, low-abrasion surfaces
• cleaning of mills and media before and after use
• closed-loop process control (no external contamination)
• defined quality control of the grinding media (no particles, no fragments)

We would be happy to help you choose the right SiLibeads® glass beads for your process. We offer personalised advice to help you minimise contamination and achieve the best possible results in your application.

The high degree of roundness ensures:

• uniform energy transfer
• reproducible grinding conditions
• reduced wear within the system
• stable flow properties in the grinding chamber

Irregular particles would result in inefficient grinding and increased wear.

In many cases, yes. SiLibeads® can often be used in existing stirred ball mills or dispersion systems, provided that:

• the ball size is suitable for the separation device
• the grinding mechanism is designed to withstand the mechanical stress
• there are no material-specific restrictions

Mechanical adjustments are often not necessary. Nevertheless, a process-specific assessment is recommended to ensure optimum performance and process reliability. We would be happy to assist you in evaluating your existing system and advise you on the transition to SiLibeads®.

SiLibeads® pharmaceutical products are manufactured under GMP-compliant conditions and are typically certified to ISO 9001 and ISO 15378.

For pharmaceutical applications, FDA Drug Master File (DMF) references are also available, as well as compliance with pharmacopoeias (e.g. Ph. Eur., USP, JP). We would be happy to provide you with the relevant documentation and advise you on regulatory requirements for your specific pharmaceutical application.

Contamination is prevented by:

• Manufactured under cleanroom conditions (e.g. ISO 7 / GMP Grade C)
• defined washing processes using water for injection (WFI)
• optical sorting and 100% inspections
• very smooth, polished surfaces

Furthermore, glass is chemically inert and does not react with active pharmaceutical ingredients, which further reduces the risk of contamination.

Borosilicate glass (Type I):

• very high chemical resistance
• low ion leaching
• preferred for sensitive active ingredients (e.g. insulin, biopharmaceuticals)

Sodium Carbonate Glass:

• more economical
• sufficiently inert for less critical applications
• lower chemical resistance than borosilicate

The choice depends on the sensitivity of the active substance and the regulatory risk profile of the application.

We would be happy to assist you in selecting the right type of glass for your pharmaceutical application and advise you on the regulatory requirements.

Glass Beads serve as a mechanical mixing and dispersing medium:

• improve the mixing of suspensions (e.g. insulin)
• ensure uniform distribution of the active ingredient
• reduce sedimentation and inhomogeneities
• support reproducible dosing

In pharmaceutical cartridges, this results in a consistent suspension and improved handling.

• Cleaning with ultra-pure water (WFI grade)
• Validated washing processes in accordance with GMP/FDA requirements
• Production in a controlled cleanroom
• Batch traceability via production and test data
• Documentation including CoA/CoC (certificates available on request)

The aim is to ensure full traceability right back to the raw material batch, as well as a high level of process and product safety.

We would be happy to provide you with the relevant documentation and assist you with any queries regarding quality, documentation and regulatory requirements.

Mechanical cell lysis (bead beating) generally involves risks arising from:

• excessive shear forces (degradation of sensitive molecules)
• potential overheating during the process
• material wear due to incorrect process design

These are monitored by:

• defined bead sizes and materials
• optimised process parameters (time, speed, temperature control)
• highly smooth, polished glass surfaces to minimise abrasion
• validated process development for reproducible results

SiLibeads® glass beads are regarded here as a standardised, easily controllable dispersing medium for laboratory and production processes. We would be happy to assist you in selecting the right SiLibeads® solution and the optimal process design for your cell lysis application.

Material properties (wells & filtration)

SiLibeads® are characterised by precisely spherical, homogeneous particles that enable a uniform and stable filter bed structure and effectively prevent bridging. The smooth surface significantly reduces the risk of biofilm and deposit formation. At the same time, the glass beads are chemically inert and microbiologically stable, meaning that no material leaches into the water.

They also offer clear mechanical advantages: their high resistance to breakage and abrasion ensures a very long service life in continuous operation and makes the material significantly more durable than traditional filter gravel.

Handling & Installation

In practice, SiLibeads® stand out for their low-dust, hygienic installation thanks to controlled filling. They are supplied in both handy 20-kg bags and big bags for larger installations, which makes handling on site easier and cleaner.

Filter design & hydraulics (wells & filtration)

Within the filter bed, the defined spherical shape ensures a homogeneous pore structure without compaction. This results in a stable, uniform flow with optimised hydraulic performance. The wide range of grain sizes also allows for flexible adaptation to different requirements in well and filtration systems.

Operational benefits

During operation, water fountains in particular benefit from reduced maintenance and wear costs. The material is regenerable and can be used over the long term, which extends the service life of the entire system.

Further significant benefits are evident in the field of filtration: filtration performance increases by up to 25–30% compared with sand, with a filtration fineness of approximately 3–5 µm. At the same time, energy consumption is reduced, as the improved hydraulics allow for the use of smaller or more efficiently operated pumps. Chemical consumption is also significantly reduced.

Another key benefit lies in the backwash process: the intervals between backwash cycles are extended by around 40–50%, whilst at the same time up to 40% less backwash water is required. The highly effective cleaning also prevents significant pressure losses after backwashing and significantly reduces overall energy consumption.

Overall rating

Taken together, these properties result in significantly reduced operating, energy and water costs. At the same time, sustainability is improved thanks to a carbon footprint that is around 30–40% lower than that of conventional filter materials. The overall result is a more efficient, more stable and low-maintenance filter system with a significantly longer service life.

The optimum grain size depends largely on the application:

• fine fractions → finer filtration, higher separation efficiency
• medium fractions → standard drinking water and process water filtration
• coarser fractions → support layers in well construction and high flow rates

SiLibeads® are typically used in defined sieve fractions, which are tailored to the specific filter bed in order to optimise hydraulic stability and filtration performance.

In well construction, the selection of the appropriate grain size depends on the classification of the soil sample in accordance with W113. SiLi can also offer Camsizer analyses of the soil sample to obtain even more precise measurement data for the design and classification.

We would be happy to help you choose the right particle size for your application. Please get in touch – we will provide you with personalised advice and work with you to find the ideal solution for your filtration or well process.

Glass balls have a very long service life because they:

• are chemically inert
• do not corrode
• are extremely resistant to abrasion and breakage

In practice, this high durability is clearly evident: in one bathroom, for example, the balls were in use in the filter for over 15 years without the filter material needing to be replaced.

Glass beads have also proven their worth over the long term in fountain construction: they were first used in a fountain as early as 2008. Since then, glass beads have been incorporated into numerous fountain projects throughout Germany.

The risk is significantly reduced compared with traditional materials:

• Smooth, non-porous surface → makes it difficult for microorganisms to adhere
• Reduced biofilm formation due to lower surface roughness
• Improved backwashing → prevents the build-up of deposits
• Extremely effective and rapid self-cleaning during backwashing

In industrial applications, a reduced tendency to form biofilms is explicitly described.

Yes. SiLibeads® Glass Beads are:

• Excellent backwashability thanks to optimised fluidisation and rapid self-cleaning
• Mechanically stable → no disintegration during backwashing
• Reusable over very long service life

This reduces maintenance costs and water consumption during cleaning.

Depending on the application and region, SiLibeads® comply with key international standards and testing requirements for use in filtration, drinking water and well applications. These include HACCP-compliant requirements, DIN 19643-2, DIN 12904, as well as NSF/ANSI 50 and NSF/ANSI 61. In addition, AWWA standards and CEN/BS EN 17978 are met, and testing by TÜV SÜD is taken into account.

The glass beads are chemically inert, suitable for contact with drinking water and designed for use in standardised water treatment and filtration systems.

SiLibeads® are used in demanding applications worldwide and meet the relevant quality and safety requirements.

We would be happy to help you choose the right solution and answer any questions you may have about certification and application.

AIR hollow beads are lightweight glass beads with no air inside them; they are vacuum-sealed and are primarily used for weight reduction and thermal insulation.

SOLID microbeads are compact glass beads that are mainly used to improve mechanical properties, rheology and surface structure.

SiLibeads® AIR glass beads generally reduce the overall weight of the material. Hollow glass beads also significantly reduce thermal conductivity. Both AIR and SOLID types can affect mechanical stiffness – depending on the loading level, particle size and matrix system. At the same time, they can improve dimensional stability.

They are used in thermoplastics, thermosets and elastomers, as well as in paints, fillers and coatings. Typical applications include lightweight components, functional coatings, filler and structural materials, and technical compounds.

A homogeneous distribution within the matrix material is achieved through the use of appropriate mixing techniques (e.g. dispersers or kneaders), optimised process parameters and a suitable surface finish on the glass beads.

Yes, in principle, segregation can occur if the formulation or processing is not optimal, particularly where there are significant differences in density or insufficient incorporation into the matrix. However, this risk can be greatly minimised through appropriate formulation and process design.

We would be happy to assist you in optimally matching materials and processes to ensure a stable and uniform product structure.

SiLibeads® AIR Glass Beads enable material savings through volume displacement whilst maintaining a low weight ratio. This makes it possible to manufacture components more easily, which in turn can reduce energy consumption, material usage and associated CO₂ emissions throughout the product lifecycle.

For such applications, SiLibeads® are manufactured from suitable glass grades that can meet the requirements of the relevant food contact regulations (e.g. EU guidelines and FDA requirements, where specified). The specific product variant and approval for the respective area of application are always decisive factors.

The SiLibeads® Glass Bead is not used to enable or prevent resealing in the traditional sense, but rather as a mechanical locking and control element within the closure system. It reliably prevents liquid from being poured back into the bottle via the spout or closure (e.g. in the event of tampering or ‘refilling’).

Inside the cap is an integrated valve system featuring a movable glass ball that is mounted in a specific valve guide. When upright, the ball rests tightly against the valve seat under its own weight, sealing it completely. When pouring, the tilt of the bottle moves the ball from its resting position, allowing the liquid to flow out in a controlled manner.

However, if an attempt is made to pour liquid into the bottle from the outside, the system reacts immediately: the resulting pressure pushes the ball back onto the valve seat and blocks the backflow. This prevents the bottle from being filled or makes it clearly visible that this is being attempted, which also makes any tampering detectable.

Provided the system is designed correctly and the right materials are selected, the risk is very low. SiLibeads® Glass Beads are mechanically stable; however, under extreme loads or in the event of design faults, the possibility of breakage cannot be entirely ruled out. Migration of glass components is generally not a concern, provided that materials meeting the specifications are used.

Quality is ensured through the use of selected raw materials, controlled production processes and regular checks of size, roundness and surface finish. In addition, every sealing ball is traceable by batch. Before dispatch, every single ball undergoes a 100% visual inspection to reliably rule out any defects.

We are happy to assist you with any questions regarding quality, specifications and the right SiLibeads® solution.

SiLibeads® Glass Beads are used as mixing beads because they are chemically inert, do not corrode and present a significantly lower risk of interacting with the filling medium. They are also lighter than many metal alternatives, which aids shaking and mixing within the container. Furthermore, they prevent metal abrasion and any potential discolouration or reactions in the product.

Yes.
Cosmetic applications place very high demands on purity, material compatibility and sensory properties (e.g. no discolouration, no odours, very low levels of impurities). Furthermore, the regulatory requirements for cosmetic applications are usually significantly more stringent.

Industrial applications are often designed with a greater focus on functionality, chemical resistance and mechanical stability, for example in paints, varnishes or technical sprays.

SiLibeads® Glass Beads, made from suitable types of glass, are highly resistant to many acids, bases and solvents. They are therefore considered to be chemically very stable in numerous industrial applications.

However, in highly alkaline or extremely corrosive chemical environments, surface changes may occur, depending on the concentration, temperature and duration of exposure. Under very strong alkaline conditions, the glass material may also dissolve completely.

In practice, however, they are successfully used in many formulations where high chemical resistance is required.

SiLibeads® Glass Beads do not stick together chemically, as glass is not an adhesive material. Blockages are primarily prevented by selecting the correct bead size, ensuring sufficient movement within the container, and maintaining the appropriate viscosity of the medium. In addition, the surface properties of the product and its formulation (e.g. the proportion of binders) play an important role in ensuring free movement within the system.

SiLibeads® Glass Beads act as optical lenses: light strikes the bead, is refracted, partially reflected at the rear, and directed back towards the light source. This creates the characteristic retroreflective effect, which significantly improves visibility when illuminated (e.g. by headlights).

The optimum grain size depends on the application and the film thickness.
As a general rule:

• smaller beads → more even distribution, a finer appearance
• larger beads → greater retroreflection at greater distances

The best performance is usually achieved by using a defined sieve fraction that is suitable for the coating layer.

Durability depends heavily on mechanical stress, abrasion and weathering.
In principle, the effect is maintained as long as the glass beads remain partially embedded in the coating and are not completely worn away. In high-stress applications, the effect diminishes over time due to surface wear.

SiLibeads® Glass Beads are generally also used in optical coatings, provided that the requirements regarding size, purity and integration into the system are met. Their suitability depends heavily on the specific coating system and the desired optical effect.

Yes, the minimum order quantity depends on the specific product type and size. Many standard products are also available from stock in specific sizes, whilst custom sizes or special types are usually manufactured on a project-by-project basis.

Do you have specific requirements or would you like a smaller quantity?

We would be happy to review your enquiry and offer personalised advice on suitable quantities and options. Contact SiLi team

Yes. For most applications, samples are provided so that you can carry out tests within your own process. In addition, we offer technical advice on selecting the right type and support with process optimisation.

Standard products are usually available at short notice, depending on stock levels and the region. Bespoke solutions or customer-specific specifications are developed on a project-by-project basis and therefore have longer lead times, which depend on the development and approval process.

Please feel free to contact us – we’ll provide you with a quick and clear update on current availability. Contact SiLi team

In addition to standard products, SiLi also offers customised SiLibeads® Glass Beads to meet specific requirements. These include, for example, special bead sizes, material requirements or purity specifications. We work with you to develop a solution that is perfectly tailored to your application. Contact SiLi team