What Is the Mix Ratio for Alginate and Water?

Our general alginate mixing instructions call for a 4:1 (water weight to powder weight) mixing ratio.

  • 4 oz. alginate to 1 pound water (~1 pint)
  • 1 pound alginate to 4 pounds water (~2 quarts)
  • 2 pounds alginate to 8 pounds water (~1 gallon)

If you need help calculating how much alginate you will need for your project, this PAGE will help.

The reason we don't recommend measuring out your alginate by "volume" is that alginate is a "compressible powder". This means that alginate can be at a wide range of densities at any one time. In fact, fully compressed alginate weighs almost 40% more than fully fluffed alginate.

If you MUST measure alginate by volume, use 2 part alginate to 3 parts water (for example: 1 cup alginate to 1 1/2 cups water). This is a decent approximation. Remember this is for volumetric measurements only and will not be as accurate as measuring by weight.

Once you get used to working with alginate and know what you like, you can portion your alginate however you want. We have several customers who mix their alginate at 7:1 (very, very thin). It works for them so we don't question them.

What happens when alginate is mixed very thinly is:

  1. The setting time is extended
  2. The setting strength is decreased
  3. The shrinkage rate after it sets is greatly increased

If you can live with this, mixing alginate thinner can save you money.