Keystone Supergel Alginate Impression Material · Fast Set · Can

• Alginate — The powder-and-water material itself, mixed in a bowl. One impression gives one plaster model.
• Dust-Free Alginate — Alginate powder the maker labels dust-free; what it sets into is alginate like the rest of the shelf.
• Alginate Alternative — A silicone, not a powder and water, so there is no bowl and no mixing by hand. It comes out of a cartridge through a mixing tip, pressed by a dispensing gun.
• Alginate Accessories — The bowl, the spatula and the measures, not the material.

The shelf also carries a reversible hydrocolloid, the other hydrocolloid family: a gel that is brought on by cooling and can be returned to the liquid state when the temperature is raised enough.

Set speed and water: the setting time depends on the water-to-powder ratio, where more powder speeds the reaction, and on the temperature, where warmer water sets faster.

Mixing ratio: the ratio is proportioned by the maker, and it varies between makers, which is why one mix comes out thick and another thin.

Water quality: some water supplies carry enough minerals to affect the accuracy and the set, and distilled or demineralised water can be used instead.

The tray: the tray is chosen for the arch and is perforated, and an alginate adhesive can be used as well as the perforations to hold the material in the tray.

Time to the model: immediate pouring of an alginate impression gave the highest accuracy of the teeth and tissues in one study. Alginate impressions cannot be kept long, and a humid environment at 4 degrees Celsius can delay pouring.