Bulk Sample Analysis
Bulk sample analysis involves the examination of a representative sample of a material thought to contain asbestos.
In our analytical laboratory, the sample is first examined by eye, and then a more detailed examination is undertaken using a low power (x20) stereo microscope. Fibres observed in the course of these examinations are categorised tentatively on the observable physical characteristics and, on this basis, are drawn from the sample and placed in the appropriate Refractive Index (RI) liquid.
Once mounted in the correct RI liquid, the fibres are then positively identified as one of the six regulated asbestos types on the basis of their detailed optical properties using polarised light microscopy (PLM) with a magnification of x50.
As necessary, one or more representative sub-samples may be prepared mechanically and / or chemically for further examination. A good example of the need to take sub-samples is with Vinyl Floor Tiles, where the tile itself might contain asbestos and/or the bitumen adhesive layer might contain asbestos.
The six regulated asbestos fibres that can be reported are as follows:
| Asbestos Variety | Nominal Colour | Nominal Composition | Group |
| Chrysotile | White | Mg3(Si2O5)(OH)4 | Serpentine |
| Crocidolite | Blue | Na2Fe32+Fe23+ (Si8O22)(OH)2 | Amphibole |
| Amosite | Brown | (Fe2+, Mg)7 (Si8O22) (OH)2 | Amphibole |
| Fibrous anthophyllite | N/A | (Mg, Fe2+)7 (Si8O22)(OH)2 | Amphibole |
| Fibrous actinolite | N/A | Ca2(Fe2+, Mg)5 (Si8O22) (OH)2 | Amphibole |
| Fibrous tremolite | N/A | Ca2Mg5(Si8O22)(OH)2 | Amphibole |
Based on the type(s) of asbestos fibres contained in the sample, the look of the sample and the description of the sample from the sampler, G & L Consultancy Ltd will classify each sample as one of the following:
- Asbestos Insulation/Coating – Pipe lagging, limpet, flock, etc
- Asbestos Insulating Board – Sheets, panels, etc
- Asbestos Cement – Sheets, panels, rainwater goods, pipes, etc
- Textured Coatings – Artex, etc
- Asbestos Textiles/Paper – Ropes, cloth, gaskets, washers, strings, etc
- Well-bound Material – Bitumen Roof felts, sink pads, etc
- Reinforced Composites – Vinyl Floor Tiles, toilet seats, window sills, etc
- Unknown – For any sample too small to be able to classify
More information on sample analysis can be found in the HSE Publication HSG248, Asbestos: The analysts’ guide for sampling, analysis and clearance procedures.