POLYSULFIDE ELASTOMERIC IMPRESSION MATERIAL:
First elastomeric impression material to be introduced, also known as mercaptan / thymol, it is a type of Rubber based impression material
* Base paste (white)
* Accelerator (brown/grey)
Available in 3 viscosities:
* Light bodied
* Medium bodied
* Heavy bodied
* Liquid polysulfide polymer 80-85%
* Inert fillers (titanium oxide, zinc sulfate, silica) 16-18%
* Lead dioxide 60-69%
* Dibutyl phthalate 30-35%
* Sulfur 3%
* Other substances (like magnesium stearate) 2%
* and deodorants
HS – R – SH ———-PbO2 + S—-> HS – R- S – S – R – SH + H2O
1) Setting time – 5-8 min.
* colder climate increases setting time.
* Drop of water accelerates the reaction.
2) Excellent detail reproduction.
3) Dimensional stability
* curing shrinkage – 0.45% due to continued reaction.
* Shrinkage due to loss of byproduct.
4) Permanent deformation – 3-5%
* highest amongst elastomers.
5) High tear strength – 7000gm/cm2
6) Good flexibility of 7%, allows elastic recovery of the material.
7) Hydrophobic- tissue should be thoroughly dried before making the impression.
8) Can be electroplated with copper.
1. long working time.
2. proven accuracy
3. high tear resistance.
4. inexpensive to use
5. less hydrophobic
6. longer shelf life.
1. must be poured with dental stone immediately.
2. potential for significant distortion.
3. odor is offensive.
4. messy & stains clothes.
5. second pour is less accurate.