Quality measurements of the thermal performance of pneumatically applied mineral fiber insulations by use of a heat flow meter device require accurate assessment of the density of material in the specific area of the heat flow meter. Current standard methods to determine this density are inadequate. A compression sampling device/technique has been developed which increases the accuracy and repeatability of density determination. Operator judgement is also greatly reduced. This device, coupled with more detailed and standardized thermal specimen generation techniques, promotes reduced density variation within the test specimen. A ±5% density variation is achievable.