Water Temperature……. Warmer water will speed the setting time of alginate and cooler water will slow it.
Mixing Ratio……. Thicker alginate sets faster, thinner sets slower- all else being equal.
Air Temperature……. Air temperature will affect how quickly the alginate will cool during and after mixing- same “warmer/faster, cooler slower” effect, however layup molds will be much more affected because of the larger “surface area to volume” ratio. Spread thin, it will be more affected by air temperature and evaporation than a bucket mold.
Humidity……. Since evaporation off the surface of the alginate will cool the mass, lower humidity will increase evaporation, cooling the mix and slowing the set. Higher humidity will lessen evaporation, allowing the alginate to stay warmer which will shorten the setting time.
Chemicals in the water……. In general, our recommendation is, “If you feel fine drinking your tap water, then its OK to use to mix your alginate”. If you filter your drinking water or there are noticeable odors from your tap water, best to use bottled water. The cheap stuff is fine. We have no idea what effects your tap water might have on the setting time or any other working property of your alginate. If you’re having problems, please feel free to contact us.