SPI Chem™ Wet Surface Replica Kit

1. Never forget that the making of these replicas is almost more of an art than a science. Be patient. Practice, including replica conversion and microscopy, before working on unique samples or extensive protocols. It could take some time before one developed the "art" of making both outstanding "negatives" and, also, outstanding "positive" replicas.



2. Some "as presented" surfaces are not "clean". For example, take a dry skin subject with dry flaky skin on the legs. While the negative replication process is described as being non-destructive, obviously, skin which is just on the verge of flaking off is indeed going to be picked up and in fact removed on the negative replica. This "flake" of skin has to be removed because it is going to interfere with the making of a good positive replica.
   
   We have found that the typical positive replica is highly efficient in terms of cleaning off such debris. Therefore for such surfaces, such as for dry skin studies, we find that best microscopy results are obtained not from the first positive replica that is made but from the second.



3. The following is the earliest published literature reference using the SPI #01090-AB Wet Replica Kit.
   
   C.A. Garber, et al., "Characterizing Cosmetic Effects and Skin Morphology by Scanning Electron Microscopy", J. Soc. Cosmet. Chemists, 27, 509-531 (November 1976).



4. The "catalyst" will react very easily with oxygen, resulting in a loss of catalytic activity. We recommend dispensing the catalyst with a something "better" than an ordinary eye dropper, such as a small Pasteur pipette and a rubber bulb. The container holding the catalyst should be opened for the briefest possible time interval. Once the catalyst is withdrawn, the container should again be tightly stoppered.



5. The catalyst should not be put in contact with any part of the human body. It could be absorbed fairly readily with completely unknown consequences. However, impressions or what we call "negative replicas" can be made of human skin so long as a) the few drops of catalyst used in the resin are first mixed well for 5-10 seconds BEFORE being applied to the skin site and b) the resin is in a sense "massaged into" the skin, that is by the time the curing system actually is applied to the skin surface, the catalyst no longer exists in its original form and is already becoming a part of the resin as part of the curing reaction. There should not be any such thing as a free molecule of catalyst at this point.
   
   Since approximately 1972, members of the technical staff of Structure Probe , Inc. have applied this replica system to literally hundreds of human subjects as well as numerous other surfaces. Sites studied have included faces, shoulders, dorsal side (e.g. back) of the hands, lips, fingernails, legs, and even the buttocks (syringe needle puncture studies). We have successfully used the system in the oral cavity to follow the long term changes of margins and also to replicate the mucousal lining of the mouth to study the effect of mouth washes. Never in all of these instances of use of clinical subjects have we ever found any subject who has reacted in any way to the application of the replicating material.
   
   While this has been our experience, we can not project to all subjects. We do not know to what degree there could be "reactors" in the general population and therefore like with any system being used for research purposes, the appropriate levels of caution should be observed. And in the event of even the slightest indication of any kind of reaction starting to occur, use of that human subject should be discontinued at once.
   
   
6. We have noted that when replicas are being made on many surfaces (many clinical subjects, for example) in the course of a day, the person actually making the replicas may, on occasion, develop some kind of apparent sensitivity, in the form of a slowly developing dermatitis. This is particularly noticed toward the end of the day. We have not found any kind of precaution that will keep this from happening in some persons. However, we do know that the likelihood of this happening can be greatly reduced by a ) making sure that there is good airflow in the room where the replicas are being made to prevent the buildup of any kind of concentration of volatiles emanating from either the resin (which we don't think is possible) or the catalyst (more likely), and b) washing the hands with soap and water every 30-60 minutes and being especially careful to pull out from under the fingernails remains of cured silicone polymer.
   
   Because there is a vigorous mixing process, and always the possibility that something could splash into one's eye, we recommend the use of safety glasses at all times when replicas are being made.
   
   
7. If "hot" surfaces are being replicated, for example, the "hot" rollers in an industrial rolling plant, while there is obviously some upper limit the system can tolerate, reducing the amount of catalyst used will reduce the reaction rate so that the cure does not occur too fast.
   

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