HYDROCOLLOIDS
- Reversible Agar-agar & Irreversible Alginate
- They both have IMBIBITION (absorbs water) & SYNERGISIS (loss of water);
- Similar reaction to water property makes them under hydrocolloids title

AGAR-AGAR
- Reversible hydrocolloid
- Major composition is water – about 85%
- Contains potassium Sulphate – thus helps accelerate the setting of a gypsum cast
- Tempering at 46°C
- Used in the lab to duplicate master cast
- No sterilization protocol needed – advantage
- Reproduction of surface details even up to 25 microns, therefore excellent
- Impression trays – have water coolant channel
- Triple tray technique