SPI-Tac Thinner for SPI-Tac Adhesive, 30ml
A unique liquid adhesive has been developed for the mounting of small particle samples that have to be individually handled for analysis, either by SEM or EDS or both. The method and indeed the liquid adhesive itself was developed by Dennis C. Ward, Chemist, Materials and Devices Unit, Federal Bureau of Investigation, Washington, DC USA and it is appropriate to acknowledge his creative ideas at this point. He was the one who opened our own eyes into the value of this unique liquid adhesive system that eventually grew into the product, SPI-Tac™.
Frequently, applications of SEM and EDS in forensic science laboratories involve the analysis of small (less than 100 µm) individually handled samples. The Ward method for the mounting of such samples that are to be analyzed this way have several advantages over the currently used selection of double sided conductive tapes, discs, and sheets.
This method uses pyrolytic carbon planchets as specimen mounts. These discs are nonporous, glass-like (because of their highly polished surfaces), flat and reusable.
Some earlier workers have also published results from their work on the available methods for the mounting of small individually handled samples.
The main component of SPI-Tac is an acrylatevinylacetate polymer dissolved in an organic solvent. SPI-Tac can be applied to a mount as a "dot" or "spot", as a fine line or as a thin film. A spot or line is applied with a capillary tube or microdropper. A thin film is applied by drawing a drop of adhesive across the planchet with the leading edge of a cover slip. The dilution of the adhesive is adjusted with acetone to give the final thickness. Once applied the adhesive remains tacky indefinitely. Samples to be analyzed are then transferred to the adhesive layer.
This method of sample mounting for SEM and EDS analysis has a number of advantages over conventional methods:
- The elemental contribution of the substrate is only carbon
- The adhesive layer is stable under conditions of high-beam current and high vacuum
- The adhesive layer is very thin. Therefore, a particle can easily be removed from the mount after analysis, and charging of an uncoated sample during observation is minimized.
- The background is structurally featureless, providing optimal photographic presentation of the sample.
- The noninvasive, nondestructive characteristic of the adhesive permits additional analytical procedures to be performed.
This method is not recommended for handling populations of very small particles such as gunshot primer residue.
|SPI-Tac Liquid Adhesive:||0.75 fl. oz. (21 ml)|
|SPI-Tac Thinner:||1 fl. oz. (30 ml)|
|UN Number:||UN 1133|
Storage conditions: Room temperature
Hazardous from the standpoint of shipping