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» 20 years of experience

» extensive collection

» innovative raw materials

» high quality products

» created to fit your industrial requirements


Lightweight hollow glass spheres can be used as a filler for the production of synthetic marble or granite effect items like kitchen sinks, wash basins and bath tubs. The reduction of the weight, the increase of the mechanical properties and the improvement of the thermal shock resistance are the main advantages of using lightweight fillers.

For sanitary applications where it is necessary to pass the thermal shock resistance test (+1500 cycles) the use of these light weight fillers with a high insulated value is strongly recommended.

Cracking around the drain hole has been a major problem in the cast polymer industry. Radial cracking generally occurs when sinks are exposed to alternating hot and cold water temperatures. Testing has been done to show the advantages the microspheres as a crack inhibiting additive. Replacing the amorfous (deformed) fillers with microspheres on an equal volume basis based on the different density of each material provide the best results. Several factors may influence the way in which microspheres improved the resistance to cracking. The spherical structure of microspheres should be superior to the irregularly shaped of the fillers particles as far as avoiding stress concentrations. The insulating value may allow the heat from the resin exotherm to be held longer in the sink and act to some extent as a substitute for the expensive post curing which is sometimes used. This insulating effect may prevent the expansion or contraction on impact of hot and cold water.

Furthermore HGS-16 hollow glass spheres can be used also in FRP laminating for the production of fiber glass swimming pools (FGSP). Due to the low density (0,17 g/cc) can be successfully utilized in polyester or vinyl-ester spray-up laminates. Because HGS-16 consists of hollow spherical particles, it offers an effective means of adding volume, while at the same time reducing weight significantly. By this way (FRP) laminates can be produced with a lower volume of resin by the use of HGS-16 as a partial resin replacement.

HGS-16 as a filler/extender in polyester or vinyl-ester spray-up laminates provides significant benefits including:

Reduced shrinkage and cracking

Lower Weight of the final parts

Additionally, we recommend hollow glass spheres to be used as a core material by the ceramic fiber glass swimming pools manufacturers (FGSP) for thermal insulation purposes.

HGS-16 is available in white powder form with a density of 0,17 g/cc. Packing in 16 kg paper bags.

HGS-21 is available in white powder form with a density of 0,19 g/cc. Packing in 13 Kg paper bags.





Physical Form

Free Flowing Powder

Free Flowing Powder




Bulk Density (g/cc)



True Density (g/cc)

Specific Gravity



Average Particle

Size (μm)



Pressure for 10%

Collapse psi, (Kgf/cm2)



Softening Point C



Oil Absorption

Gm oil / 100 cc



Thermal Conductivity

BTU in/h/sq/F



HGS-16 is a lightweight filler in white powder form with density 0,17 g/cc which is used not only to reduce the weight of the final product but also to increase the thermal shock resistance and the mechanical properties of the final items.

 A pilot recipe is the following: 21 parts of resin, 47 parts of calcium carbonate or dolomite or ATH (Aluminum Trihydrate)  and 2,4 parts of HGS-16. In this case the expected reduction of the weight is 30% approx. This initial recipe can be adjusted depending on the viscosity of the resin so that the mixture to have sufficient flowing characteristics.   
Mixing instructions
Low shear mixing equipment should be used, such as cement and Hobart mixers. There are two ways in which HGS can be added to the formulation:

1. The HGS can be added directly to the resin in order to obtain good wetting characteristics. The amorfous filler like calcium carbonate or dolomite or ATH is added to the mix after the HGS is thoroughly wetted. The remainder of the formulation can then be added in the usual manner.

2. Mix the formulation in the usual manner and after the catalyst is added, then add the HGS and mix till the HGS is no longer visible.

In any case we advise you to mix the HGS filler with resin in low speed so that to avoid crushing of the hollow glass spheres and have success to your test.  To reduce dusting a suitable cover on the mixing equipment can be used during mixing procedure.

In the construction system of fiber glass swimming pools (FGSP) HGS-16 can be used as following:

a. The addition of 4% of HGS-16 (per weight) to polyester or vinyl ester resins formulations increases the volume of the system. Fiberglass reinforced (FRP) laminates can be produced with a lower volume of resin by the use of HGS-16 as a partial replacement and results in approx.  20% reduction of the weight of the laminate.

b. For building the ceramic core material by applying a putty which is a mix of approx.:  1,5 kg of HGS-16  and 5,6 kg of resin (polyester or vinylester). This layer should be built between two fiber glass laminate layers. Usually used layers are polyester-polyester or vinylester – polyester or vinylester – vinylester.

In any case the addition of HGS to the building of a fiber glass swimming pool (FGSP) results  in  a new final product with better mechanical properties and thermal shock resistance.

Call us today at +30 210 5593707 / +30 210 5596380 or send us your email to kesteco@kesteco.com

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