HydroSpan 100 is a unique two-component, Flexible, 100% solids (contains no V.O.C.), polyurethane elastomeric compound. HydroSpan 100, when fully cured provides a simple method for expanding three-dimensionally molded parts. Expanding parts is done by simply molding the part with HydroSpan 100 to form a rubber master. After curing 24 hours at room temperature the molded HydroSpan 100 part is soaked in room temperature water and allowed to expand. Full expansion is 61% larger than the original part. Full expansion of parts can be achieved in 5 to 14 days depending on cross section thickness of the part. Thicker cross sections take longer while thinner cross-sections require less time.



Application and Mix Ratio

Mold Preparation

HydroSpan 100 can be molded in almost any kind of mold as long as it is fully prepared before filling with the uncured polymer. Release agents used in the molding process inhibit the absorption of water thus slow down the expansion of the part. All waxes and release agents should be thoroughly removed with mineral spirits or acetone before the part is soaked in water. Parts molded in silicone mold require no preparation before soaking. All surfaces should be free of dirt and visible moisture. Depending on relative humidity and temperature, parts can be handled in 1 to 2 hours. Full cure is attained in 24 hours at 72°F.

Application & Mix Ratio

Mix two (2) parts of component A to one (1) part of component B by weight (use a maximum batch size of no more than two (2) quarts of component A to one (1) quart of component B [2/3-gallon total mix]). Pour both components into a clean one (1) gallon plastic pail and quickly mix using a spatula for batch sizes of ½ gallon or less or jiffy mixer and electric drill for larger batch sizes, take care to scrape side of pail with a flat spatula to include all of the unmixed liquid (do not use square or round rod as mixers). Mix for about 1 minute and quickly pour into the prepared mold. After about 6 to 8 minutes HydroSpan 100 thickens to a gel-like consistency. It is important to have all pouring completed before this occurs.

HydroSpan 100 is packaged in convenient 3-quart, 3-gallon or 15-gallon kits. Liquid containers should be maintained at 72°F for best results. Warmer temperatures will decrease working life; cooler temperatures will increase application time. Choose a work area that is free from visible moisture and capable of maintaining a temperature range of 70°F to 90°F. After temperature stabilizing the liquid component A and component B to 70°F to 80°F, remove the lids of each container and stir Component B thoroughly using a flat handheld spatula or jiffy mixer and electric drill (both are available from Industrial Polymers, Inc.). Gloves, eye protection, and respirators must be worn during spray application (see Industrial Polymers material safety data sheet for more details).

Expanded Parts

Once the HydroSpan parts have expanded to the desired size a final mold should be made as soon as possible. The preferred mold making material is Platinum-Cured Silicone. Expanded HydroSpan 100 parts will shrink back to their original size if allowed to dry out.

Problem Solver




Material Sets too quickly

Liquid components too warm before using

Condition liquid to 72°F


Purge Liquid containers with Dry-It after days use

Uneven color rubs off

Color is not completely dispersed

Stir color into component B before adding component A

Surface bubbles

Moisture contamination

Application surface should be dry


Must be allowed to cure overnight in a dry environment

Cured HydroSpan 100 will not expand

Mold release agent on the surface

Clean cured parts with mineral spirits or acetone before soaking in water or Use Silicone molds

Sticky spots

Uneven mixing

Premix exactly 2 part A to 1 part B by Weight

Do not mix more than ½ gallon by hand, larger batch sizes require a Jiffy mixer and electric drill

Use a flat spatula



Working Properties

Mix Ratio By Weight

100 parts A/ 50 part B

Mix Ratio By Volume

100 parts A/ 53.57 parts B

Viscosity @ 72°F (Component A)

2000 cps

Viscosity @ 72°F (Component B)

600 cps

Viscosity @ 72°F (Mixed)

1200 cps


Part A:



Part B:

Translucent Blue



Translucent Blue

Working Life @ 72°F

10-12 minutes

Full Cure Time* @ 72°F

24 hours

*Full Cure time depends on temperature and relative humidity.


Physical Properties

Specific Gravity: (Part A)


Specific Gravity: (Part B)


Specific Gravity: (Mixed)


Weight/Gallon Part A

9.16 lbs.

Weight/Gallon Part B

8.55 lbs.

Weight/Gallon Mixed

8.95 lbs.

Cubic inch per lb. of product


Hardness @ 72° F

ASTM 2240-85


Expansion rate @ 72˚F for 14 days



Clean Up

Dispose of all empty HydroSpan 100 component containers in accordance with local, state and federal regulations. Empty component containers can be rendered non-hazardous by rinsing the containers with a small amount of mixed material and allowing material to cure for 24 hours. The containers will then contain non-hazardous cured urethane.

Storage and Shelf Life

HydroSpan 100 liquids should be stored in the original, unopened containers in temperature between 75°F and 85°F (24°C and 29°C). The shelf life of materials, when kept in unopened sealed containers, at the recommended storage temperature, is six months. Containers should not be opened until ready for immediate use. When resealing opened containers purge with dry gas, Dry-It (available from Industrial Polymers, Inc.). To avoid air entrapment, undue agitation of containers should be avoided.


Shipping Class: Class 55 Non-hazardous