Microballoons

General Description

These bubbles are actually hollow glass spheres. Because this high-quality glass is very crush resistant, the foam is much stronger, stiffer and water-resistant than any foam made by chemical foaming. These foams displace 4-6 times their weight in most resins and improve the handling characteristics of the base resin. They have a low bulk density and are nontoxic.

Velocity Use

Glass bubbles/Microballoons are supplied in a huge bag, and are used for both structural fill (as in making a radius prior to laying down BID tape), thickening (as in Jeffco), and for aesthetic fill on exterior surfaces. The usage depends largely on the epoxy being thickened with the balloons.

Product Description

Microballoons are a lightweight free-flowing white powder consisting of microscopic, hollow, glass ball clusters. Microballoons are a specially processed silica glass, classified to insure uniform particle size and product performance and is hydrophopic (does not readily adsorb moisture). It disperses extremely well when mixed with various resins or plaster. Microballoons do not absorb resin and therefore provide maximum filler function. Cured systems are more water resistant and have a higher temperature resistance in addition to being more thermal and electrical resistive.

In addition, microballoons reduce the weight of the finished the product and offers improved workability (nailing, sawing, drilling, etc.) further reducing costs. It has been used extensively in molded vanities, doors, columns, lighting fixtures, picture frames, etc. It is more more easily sanded than fiberglass flock, so it can be used in polyester systems where extremely high-strength is not required. It can be used in sandable pastes to repair imperfections in wood and fiberglass boats, cars or other parts. Many engineering students at the university level have used microballoons to increase buoyancy and as a lightweight and inexpensive filler in cement canoe projects.

Product Specifications

PROPERTIES: Specific gravity: 0.18 Effective Particle Density: 11.2 lb / cu ft Surface pH: 7.0 Free moisture by weight: 0.4% Dry bulk density: 0.13 g/cc (8 lb/cu ft) Thermal conductivity (K): 0.36 Average particle size: 75 microns Melting point: 2300°F Natural Color: White ASTM D1483 Oil Adsorption, g oil/100cc: 30 Water Adsorption: 0.3% max Average Particle Size: 75 microns Particle Size Range: 1-300 microns Approximate compressive crush strength: 1,800 psi

CHEMICAL ANALYSIS: 73% SiO2 17% Al2O3 5% K2O 3% Na2O 1% CaO + trace elements

PARTICLE SIZE DISTRIBUTION: + 50 Mesh: 2% -50 +100: 15% -100 + 200: 33% -200: 50%

Packaging Weights

Aircraft Spruce sells glass bubbles in 1 and 5 lbs bags.

Directions for Use

Mix resin and hardener as directed, then fold in the glass bubbles. Upon cure, a strong, low-density product results which is easy to sand and file. May be shaped to form compound angles and curves. The term "micro" was applied to the mixture of microspheres and epoxy early in the development of composite structures. Although microspheres have been replaced by glass bubbles the word "micro" is still commonly used to reference the mixture. "Micro is used to fill voids and low areas, to glue foam blocks together and as a bond between foams and glass cloth. Micro is used in three consistencies - (1) a "slurry" which is a one-to-one by volume mix of epoxy and glass bubbles, (2) "wet micro" which is about two to four parts glass bubbles by volume to one part epoxy, and (3) "dry micro" which is a mix of epoxy with enough glass bubbles to obtain a paste which will not sag or run (about five parts to one by volume). In all instances, glass bubbles are added to completely mixed epoxy resin and hardener. Wet micro is used to join foam blocks and is much thicker than slurry (it has the consistency of honey) but can be brushed. Dry micro is used to fill low spots and voids and is mixed so that it is a dry paste and will not sag. Apply with a putty knife. Never use micro between glass layers.

Safety and Handling

Caution - When mixing epoxy and glass bubbles, wear a dust mask and keep your face away from the balloons that may float up into the air. Although glass balloons are inert, they can lodge in your eyes or in your lungs and cause problems. Handle with care
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