We had a delay in the arrival of 21kg of alginate because the atmosphere was too damp in the supplier's warehouse to pack!
Eventually, it arrived after the Easter break and we have been making what feels like green slime. Alginate is great for making quick and detailed molds. You may be familiar with the minty version your dentist uses to take an impression of your teeth.
We are using Accucast LS680 a low shrinkage product. It arrives as a squeaky powder which you mix with water. The temperature of the water matters, so after mixing you have a warmish thick goop, which is a very weird feeling. In about 6 minutes it is set around your object so no time to waste. Set alginate feels like a very firm gelly mousse and it is very easy to cut out your object or if you are lifecasting a wiggle will usually do.
Unfortunately, there are some downsides to alginate. You have a short window to pour your positive (wax, plaster etc) before the alginate begins to shrink. Spongelike it doesn't actually absorb water and starts to shed liquid - which makes it very slippery indeed. It can't really hold itself up so it needs support and it tears easily.
But with the right project, it is perfect.