Calculating microspheres per gram

During scientific experiment design and analysis it is common to need to know the number of spheres per gram of dry material.  We have put together the table below to help speed up the process.

If you have material of a density different from those listed in the table, divide the number of spheres per gram in the density ~1.0 g/cc column by the true particle density of your material to get an estimate of the number of spheres per gram.

Note: This table assumes the mean diameter is half way between the upper and lower size.

Microparticles for simulating fish egg dispersion and recruitment

Understanding survival and mortality of fish in the early life stages has been a fundamental issue in biology and a central problem in fisheries oceanographic study for more than a century. It has been argued that most marine fishes begin life as an egg that floats in the sea, and, during their evolutionary history, the early life of fishes has surely been shaped to ensure the “continued existence of species” by the sheer pressure of natural selection, and stated that a fish to survive must deal with and exploit its physical and biological environments. However, although we are now in the 21st Century, there still remains a lot to be made scientifically clear in the early life of fishes. In the present lecture, I will talk about fundamental issues in the isolated floating eggs of marine fish, which many pelagic species spawn in thousands, millions, or sometimes almost billions during a life of an individual female. The topics contain description and discussion on the egg size, buoyancy and rising speed. Measurements on the eggs naturally spawned in aquaculture systems are firstly introduced. Several examples of egg vertical distribution, accumulation and dispersion observed through field surveys will be shown to consider how the egg size and buoyancy are adaptive to survive in the pelagic environment.¹

Scientists who study fish require artificial micro-particles to simulate fish eggs and their dispersion behavior in water. In order to accurately simulate the dispersion of fish eggs it is important to use particles of the proper size and buoyancy/density. Particles with accurate size ranges and densities are now available from Cospheric LLC. Densities from 1.00g/cc up to 1.12 g/cc are available in size ranges from 10-27um on up to 0.85-1.0mm. Sea water particles of 1.025g/cc (UVPMS-BG-1.025), and fresh water beads of 1.00g/cc are in stock and available for quick delivery.

Most fish eggs are in the size of 0.5-5mm¹ with the typical size of 1mm being the most common.   Salt water fish eggs tend to be slightly less dense than medium saltwater at a density of about 1.020g/cc¹.

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High Density Glass Microspheres

Barium Titanate Glass microspheres are high density solid glass spheres.  At a Density of 4.5g/cc these solid glass spheres can be used for many scientific applications where high density and optical clarity is needed.  In addition to high density they also offer an index of refraction of more than 1.9.

Bulk quantities are available in 30-100um and 0.3-1.0mm size ranges.

For experiments requiring the highest precision the beads can be purchased in classified grades offering >90% of the spheres within a specific size range.  Standard Sizes include the narrow ranges below.

38-45um, 45-53um, 53-63um, 63-75um, 75-90um, 90-106um, 0.25mm-0.3mm, 0.3mm-0.35mm, 0.36mm-0.42mm, 0.43mm-0.5mm, 0.5mm-0.6mm, 0.6mm-0.7mm, 0.71mm to 0.85mm, and 0.85mm to 1.0mm.

Product pricing and availability can be found under Cospheric’s BTGMS (barium titanate glass microspheres)

High Index of Refraction Retroreflective Glass Microspheres

Barium Titanate Glass Microspheres are excellent for use as a functional retro reflective additive  to paints and coatings.  Spheres with sizes of about 50 micron (~0.002 inches) mean diameter provide a small enough size for most coatings while offering a large enough size to reflective a significant amount of light.  Barium Titanate Glass Spheres are offered in both partially aluminum coated retro-reflective version for addition into transparent coatings, or as uncoated glass spherical powder for uses in colored paints.

Barium Titanate Glass microbeads offers one of the highest indexes of refraction with an IR greater than 1.9 which provides high intensity retroreflectivity from these spheres.

For those applications calling for a high density filler, barium titanate glass spheres offer a density of 4.5g/cc, that is almost double that of the more common soda lime glass spheres.   In addition to a high density, barium titanate glass spheres have a hardness of about 55-65 on the Gardner scale and a crush strength of over 30,000 psi (207 Mpa) making these spheres very durable in high wear environments.

The spheres offered by Cospheric as product ID:  BTGMS (uncoated ) and P2453BTA (aluminized) are produced in the USA, and are Lead free.

Patent Review: Process for forming hollow glass spheres up to 5mm

Hollow glass microspheres are currently commercially available in sizes of up to 0.2mm, but not larger. William Mathews et. al offer a potential solution for producing larger hollow glass microspheres in patent 3,838,998.   They present a method which would enable the production of hollow glass spheres in sizes up to 5mm in diameter.   As can be seen in the details of the patent, the process is quite complex, and seems to only offer pilot production capability, which would reason why we do not currently see hollow glass spheres in the 0.2-5mm range.

US Patent: 3,838,998

PROCESS FOR FORMING HOLLOW GLASS MICRO-SPHERES FROM ADMIXED HIGH AND LOW TEMPERATURE GLASS FORMERS

Abstract:

A process for forming hollow glass micro-spheres with walls of controllably variable thickness in a size range of 50 to 5,000 microns, embodying (1) preparation of a water slurry of finely particulated, high temperature and low temperature glass formers; (2) prilling the slurry in a vertical spray drying tower; (3) separating and supporting the individual prilled feed material; (4) heating the feed material to glassification of the high temperature glass former while maintaining appropriate geometry and shell thickness and (5) cooling the finished product. The high temperature glass former is preferably a naturally occurring soda feldspar. The process is particularly adapted to form thicker walled micro-spheres of larger size and high quality.