Glass Microspheres

5 star rating

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  • Item
  • Description
  • Price
  • Qty
  • 22-A
  • 22-A
    1/2 Gallon (4 oz)
  • $17.95
  • 22-B
  • 22-B
    Carton (3 lbs)
  • $89.95
  • 22-C
  • 22-C
    Carton (6 lbs)
  • $159.95


Lightweight, Sandable Filler for Surface Layers

When blended with resin, these hollow glass spheres make a lightweight, sandable filler, perfect for filling in fabric weave, shallow blisters, and the surfaces of core materials. The average bubble is less than 70 microns, about a quarter of a grain of salt. Select this unique size and shape for a variety of reasons:

  • Tiny spheres blend readily for an evenly spreadable paste.
  • They are adaptable to a variety of production processes such as spraying, casting, and molding.
  • Low density reduces weight, lowers costs, and enhances properties for finished parts.
  • Spheres provide lower viscosity, improved flow and reduce shrinkage and warp.

This filler is compatible with epoxy, polyester, and vinyl ester resin systems. Add filler after adding catalyst to resin.

Mix ratio is 3:1 (filler to resin by volume).

Glass microspheres, also known as glass micro balloons or glass beads, can be used as a filler material in composite applications. Here is some information about their use in composites:

  1. Lightweight Filler: Glass microspheres are hollow spheres made of glass, which makes them extremely lightweight. They have a low density allowing them to reduce the overall weight of the composite material.
  2. Density Control: Glass microspheres can be used to control the density of the composite material. By adjusting the volume fraction of glass microspheres in the composite matrix, it is possible to achieve a specific target density while maintaining desired mechanical properties.
  3. Improved Mechanical Properties: The addition of glass microspheres can enhance the mechanical properties of the composite. They can increase the stiffness and compressive strength of the material, especially in applications where weight reduction is a priority.
  4. Improved Dimensional Stability: Glass microspheres have low thermal expansion coefficients, which can improve the dimensional stability of the composite. They can help minimize the effects of thermal expansion and contraction, reducing the risk of warping or distortion in the final product.
  5. Thermal Insulation: Glass microspheres have good thermal insulation properties. When incorporated into a composite material, they can help reduce heat transfer, making the composite more resistant to temperature changes.
  6. Improved Surface Finish: The use of glass microspheres in composites can help achieve a smoother surface finish. The microspheres act as fillers that fill voids and surface imperfections, resulting in a more uniform and aesthetically pleasing appearance.
  7. Processing Benefits: Glass microspheres are easy to handle and can be mixed into resin systems without significant changes to the processing parameters. They can be easily dispersed within the matrix and do not require extensive modifications to the fabrication process.

It is important to note that the specific properties and performance of composites using glass microspheres will depend on various factors, including the type and size of microspheres, the matrix material, the processing conditions, and the intended application. Therefore, it is crucial to consider the desired outcome.


Fillers, when ordered alone, will typically ship in a small or medium box. Where possible, we will combine ordered items to reduce the number of boxes shipped.


Glass Microspheres Glass Microspheres available in two sizes: One 1/2 gallon (#22-A) One carton (#22-B)


5 star rating


Mar 26, 2023  |  By Jim Brunton

I experimented with a small quantity of these about a month ago - after the first use I decided that this was a product that I would make sure that I always had on hand. I immediately ordered a 3 pound box. As a filler product the Microspheres have it all - lightweight, can be mixed to any level of density and any level of cure time. Sands easily and without air pockets. Feathers well. Most of my projects are building or repairing racing kayaks, this is a perfect light-weight product to aid in a smooth finish for most of my repairs.


Aug 24, 2018  |  By Phil

When using microfiber in my bonding epoxy as a filler, I can use half to two thirds less catalyst and resin while building rods and achieve the same bonding strength since the fibers are mixed into the epoxy and encapsulated by it. Fishing rods don't require much epoxy in construction bonding as a general rule, but often there is a need for more bonding material than expected for a really good bond between the blank and handle. When a miscalculation is made, filling in with microfibers saves a lot of headaches and epoxy, while achieving a very good quality bond.


Oct 22, 2017  |  By Trevor Brasch

Very nice to work with, light weight. fine textured and fairs very well. becomes almost clear when used in epoxy

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