Photograph of chopped fiberglass insulation Building or House Dust Particle Identification Screen for Fiberglass Particles
Test Laboratory Procedures

  • DUST ANALYSIS for FIBERGLASS - CONTENTS: Simple Method for Identifying Contents of House Dust to Screen for Building Insulation. Photographs of Unbonded Fiberglass Insulation - Blowing Wools. How to Distinguish Between Fiberglass Fibers & Fabric Fibers in House Dust. Microscope procedures for identification of fiberglass. Fiberglass Lab Test Warnings & Tipss
  • POST a QUESTION or READ FAQs about fiberglass dust particle identification procedures & testing

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House dust test procedure or other building dust sampling for fiberglass: this indoor air quality testing article describes the process for laboratory identification of particles found in indoor air or settled dust collected in residential and light-commercial buildings.

Typical components of house dust are dominated by fabric fibers and skin cells. We may however find either high levels of common problem particles (mold, allergens, fiberglass or other insulation fragments) or low levels of particles that by their nature still indicate a problem.

Our page top photo shows a vacuum sample of fiberglass building insulation. The bonding resin is plainly visible in our lab photo - often the color of the binding resin in fiberglass insulation helps trace insulation dust in a building back to its source. Not all fiberglass insulation includes resin binders however.

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Simple Method for Identifying Contents of House Dust to Screen for Building Insulation (fiberglass fragments or other insulation materials)

This article describes easy steps taken in the forensic lab that permit reliable particle identification and distinguishing among fiberglass insulation, mineral wool or "rock wool" and cotton or other fibers.

Photographs of Unbonded Fiberglass Insulation - "Blowing Wools"

Certainteed blown in fiberglass (C) Daniel Friedman Certainteed blown in fiberglass (C) Daniel Friedman

Above (left) we show a macro photograph of white blown-in unbonded InsulSafe® building insulation sold by CertainTeed and provided by a homeowner who asked our lab to study dust samples from her home.

At above right is the same insulation shown in the stereo microscope at about 20x, and below the same material is magnified to 720x.

How to Distinguish Between Fiberglass Fibers & Fabric Fibers in House Dust

Certainteed blown in fiberglass (C) Daniel Friedman fibers not fiberglass (C) Daniel Friedman

Above (left) we show a 720x micro-photograph of white blown-in unbonded InsulSafe® building insulation sold by CertainTeed. At above right our photo shows the dominant particles in the dust sample from the home under study.

Magnified to 720x the fibers we found were primarily cotton, with some linen and a few synthetic fabric fibers. There was virtually none of the insulation fibers provided for comparison (above left) as a possible source of dust in the home.

fibers not fiberglass (C) Daniel Friedman fibers not fiberglass (C) Daniel Friedman

Above (left) a client photo shows a heavy and rapid dust accumulation on building surfaces. At above right our lab photo shows that the prime contents of the dust were fabric fibers and starch granules, not building insulation in this case. - DF & WW 6/2010.

Fiberglass Lab Test Warnings & Tips

Watch out: when preparing a laboratory sample for microscopic examination for the present and level of fiberglass fragments (from insulation or any other source), choose the mountant liquid wisely. If you use a slide mountant whose refractive index is close to that of glass fibers, detection of small fiberglass fragments may be difficult or impossible even though they may be present at high levels.

Thus while it may be trivial to distinguish fiberglass from other fibers found in building dust, it the mountant is not properly selected (with the proper n or refractive index), or if the microscope is not properly adjusted, the technician can completely miss high levels of ultra-fine fiberglass fragments.

Fiberglass Lab Tip - watch out for ultra-small fiberglass fragments

While detection of large fibers of any sort in a microscope sample is relatively easy, in our OPINION, some fiberglass dust studies have been faulty in design because technicians seriously under-report the presence of ultra-small fiberglass insulation fragments in dust samples. This error occurs because of a combination of:

  • Improper refractive index mountant
  • Poor slide preparation
  • Failure to adjust the microscope to high magnification to screen for particles near 1u in size

In sum, as forensic microscopists know well, if you don't look for a particle or a particle in the proper size range, preparation, and magnification, you will not find it. Details about the problems of detecting ultra-small fiberglass fragments are


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Or see see DUST SAMPLING PROCEDURE where we also discuss finding mold in indoor dust samples

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DUST ANALYSIS for FIBERGLASS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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