Tapes vs Ghost Wipes

Tapes vs Ghost Wipes

Without a doubt, one of the biggest ‘grey-areas’ for asbestos site validation, is how areas are deemed as ‘clear’ or if additional cleaning/decontamination is required.  As Focus only provides analytical services, we tend to ‘stay in our lane’, when raising opinion on how this is implemented on-site. We do however note the various methods of collecting settled dust/surface deposition samples and the pros and cons in the lab.

As we see it these are as below:

Tape samples:
PROS: This method is effective on surfaces that are soft and/or porous. The adhesive tape surface grabs and holds the surface particles very well. In addition, the sample is easily prepped for analysis. All that is required is the tape to be peeled apart whilst observing the dust and debris under the scope. To isolate a fibre, the analyst simply picks them from the tape surface for further qualification under polarising light analysis. This approach tends to ‘grab’ everything from the subjected surface, due to the adhesive nature of the ‘stickiness’ of the tape.
CONS: Tape sampling should be applied a limited amount of times, as it looses its ‘stickiness’. Therefore in dusty areas, it can be only applied once and over a small area if it is to be representative (should a visual fail due to visual dust anyway though?). As such, asbestos fibre/debris could be left behind if it does not stick to the tape surface
Ghost wipes
With Ghost wipes additional processing of furnace ashing is required, this is to remove the swab itself plus any interference material. 
PROS: All that is left generally is asbestiform material/fibres. By removing all organic interference fibres (which can effect asbestos characterisation). This can be helpful when the sample renders a large concentration of organic and synthetic fibres.
CONS: The preparation of Ghost Wipes is done in a muffle furnace at 400°C (±30°C ). Because chrysotile can denature at temperatures from around 450°Cit is essential that there is no temperature ‘creep’ or ‘impulse’. If this occurs there is a change that the laboratory could deem asbestos fibres as non-asbestos. Therefore it is critical that the laboratory furnace is calibrated to reduce this from occurring. In addition, some consultants believe that amphiboles may not be reliably captured by ‘wet-wipes’. Amphiboles tend to be more hydrophobic than serpentine fibres, such as chrysotile.Below are some comparative images of surface samples via tape samples versus Ghost Wipes.278dc08b 3b50 46d3 9b5f 461dceeb65df

3bfe48a2 ce89 4252 8e01 9e53e9161c98