All of the following statements about addition silicone impression material are true EXCEPT:

Properties of Addition Silicone Pleasant odor and color. This may also cause allergic reaction so direct skin contact should be avoided. Excellent reproduction of surface details. Polyvinyl siloxanes are currently considered to reproduce the greatest detail of all the impression materials. The international standard for dental elastomeric impression materials states that a type 3 (light bodied) impression material must reproduce a line 20 μm in width. With the exception of the very high viscosity putty materials, all polyvinyl siloxanes (light, medium and heavy body) achieve this very low viscosity materials can reproduce lines 1-2 μm wide. Setting time ranges from 5 to 9 minutes. Mixing time is 45 seconds. Working time may be extended by chilling the tubes. Gains of up to 90 seconds have been reported when the materials are chilled to 2oC. It has the best dimensional stability among the elastomers. It has a low curing shrinkage (0.17%) and the lowest permanent deformation (0.05-0.3%) Early materials has the problem of hydrogen gas formation. If hydrogen gas is liberated pouring of stone is delayed by 1-2 hours to prevent formation of air bubbles in the stone cast. Current materials do not have this problem because of the addition of palladium. It has good tear strength (3000 g/cm). It is extremely hydrophobic, so similar care should be taken while making the impression and pouring the wet stone. Some manufactures add a surfactant (detergent) to make it more hydrophilic. It can be electroplated with silver or copper. However, hydrophilic silicones are more difficult to electroplate because of the surfactant added. It has low flexibility and is harder than polysulfides. Extra spacing (3 mm) should be provided in the impression tray. Care should also be taken while removing the stone cast from the impression to avoid any breakage. Shelf life ranges from 1 to 2 years.