How To Use HydroGel® N Alginate Mold Compound


When using Hydrogel N is important to remember it's mostly water. This makes it great for contact with skin, especially when you are doing body molds. But a small test cure should be made prior to using to be sure Hydrogel N releases cleanly and does not damage water sensitive surfaces. Hydrogel N can be poured on most surfaces with minimum preparation. A thin coat of petroleum jelly or Pol-Ease 2300 release agent will seal most questionable surfaces adequately.


Weigh or measure proper amounts of Hydrogel N powder and room temperature water. Mix together rapidly, but avoid whipping in air. A turbo mixer on a variable speed drill is recommended. Thicken with more powder, thin with more water. Apply to surface with a flowing motion pushing air out ahead of material. Optional liquid retarder may be premixed with water to extend working time.

Hydrogel N will not bond to itself unless the previous mix is not completely gelled. Thus, a large mold requiring more than one mix should be made by mixing a series of mixes within five minutes of one another. Wiping a saturated solution of water and baking soda (sodium bicarbonate) on gelled Hydrogel N will aid bonding of a fresh mix to gelled material. Food color added to the bonding solution aids knowing where it has been applied. As soon as Hydrogel N is firm, mix and apply a mother mold of plaster (plaster of paris is fine). When plaster shell is set, remove the Hydrogel N mold and for best dimensional stability, immediately make a positive casting.


Plaster or waxes below 212°F may be poured in Hydrogel N molds. Castings should be made in freshest possible molds for best results. Hydrogel N molds will shrink and distort as water dries or is lost. They may be kept usable in plastic bags or sealed containers for a short period of time, up to a few days. Molds should then be discarded.


Hydrogel N powder may cause dust when being handled. If dust is present wear a dust mask and avoid eye contact. Hydrogel N is not for human consumption or use against mucous membranes. Skin contact should be kept as short as possible. Hair must be slicked down with petroleum jelly.

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