Poly vinyl siloxane putty impressions

At one of my private practice jobs the material we use for fixed prosthodontic impressions is PVS putty with a light body wash. I have used this with reasonable success and it takes reasonable impressions as the viscosity of the putty pushes the light body down the tooth, however this can be disadvantageous sometimes as the putty itself fails to flow. Therefore it will be hopeless in capturing an impression of the sulcus if your light body hasn't made it in there. Additionally, if the tissue is quite floppy, it can displace the tissue out of the way but can just as easily push the tissue back onto your preparation undoing the action of your tissue retraction. Ideally you would put a medium/heavy bodied material on top of the light body to act as an intermediary between the two material viscosities.

One issue I've been having coming into the summer months is that the putty reaches an early set stage extremely fast where it becomes stiffer and forms cracks and distortions when pressure is placed on it. This is bad as a lot of pressure is needed to seat the tray, the light body may not integrate with the putty and impression distortions may occur without me realising. This was visualised recently when I took an upper arch impression for a crown using a lower tray and when I removed the tray it had completely bent out of shape with the two posterior segments pointing in different directions. When put on the table, I could see how wonky the tray had become. The concern here is that once the tray is removed from the mouth, the elasticity in the tray will spring back somewhat and the impression material will distort and therefore be useless. Perhaps an upper tray (with palatal coverage) would provide extra rigidity to counteract this but the problem will still remain with the buccal walls flexing. To be safe, if putty is to be used, a metal tray is needed. 

To get around the early set of the material in warmer temperatures, I will tend to put the putty containers and light body guns in the fridge and remove them just before the impression. It doesn't seem to affect the material handling and gives a significantly longer setting time. In fact, I noted the material took almost twice as long before I was comfortable to remove it. I will tend to only do this with multi unit cases as if you work cohesively and efficiently as a team, room temperature materials should work fine for single units.