Brush-On Molding Gels

Molding gels are urethanes which become very thick after the part A and B components are mixed together. Having a urethane product which is very high in viscosity (a paste consistency) allows the product to be applied very thick on a surface without sagging or running down.  This is very helpful when you are making a brush on rubber mold skin from a large 3 dimensional master model.  A brush on paste consistency is also helpful if you want to brush into an open faced mold to make a large flexible rubber skin for animatronics applications.  If you would like to make a rigid plastic shell instead of a flexible rubber skin we manufacture UraGel 770 which cures to become a hard surface.   UraGel 770 is sometimes used in open faced rubber molds to make large masks or reproduction suits of ancient amour.  UraGel 770 can be brushed into a silicone rubber mold ¼ of an inch thick or more to make high durability rigid plastic parts.  Customers frequently use UraGel 770 over InstaGel to create a hard supporting mother mold for their brush on rubber mold.  The InstaGel and UraGel products are available in small 2 quart trial kits, gallons or 5 gallon plastic pail quantities.  Please call 800-766-3832 / 713-943-8451 or email us for current pricing and delivery options.

We manufacture 4 brush-on gel products for making flexible rubber molds and 2 brush-on gel products (UraGel 770 & 780) which cure to be hard plastic. Instagel 20 is the softest and Instagel 50 is the hardest flexible brush-on rubber we manufacture.  The hardness of cured InstaGel rubbers increase from 20 Shore A to 50 Shore A, see chart below.

InstaGel 20 flexible (25 shore A) brush-on mold making flexible rubber

InstaGel 30 flexible (30 shore A) brush-on mold making flexible rubber

InstaGel 40 flexible (40 shore A) brush-on mold making flexible rubber

InstaGel 50 flexible (50 shore A) brush-on mold making flexible rubber

UraGel 770 Hard (75 Shore D) rigid brush-on mold back-up material or for making rigid parts in mold

UraGel 780 Hard (75 Shore D) This product can be used as a base coat for UraGel 770 when working with molds which have very fine surface details,  more fluid than 770 version picks up greater surface detail in mold.

Our brush-on gel products can be hand mixed or drill mixed with Jiffy mixer attachment. If you are mixing by hand it is important to mix quickly and vigorously to insure the A and B components are thoroughly mixed before product begins to thicken in container. When mixing by hand or with electric drill you must use a flat mixing spatula to scrape the sides and bottom of mixing bucket thoroughly. Any traces of unmixed product will create weak areas or sticky spots in the cured product. After mixing equal volumes of A and B components together our gels transform into a creamy paste consistency. You may apply our molding gels up to 1/2- inch thickness in a single application without sagging or running. These products remain brush-able for approximately 10 to 15 minutes after mixing.  We recommend you allow 24 hours curing before using the finished mold. Fabric or chopped fiber can be added to enhance physical properties of cured gels both rigid or flexible. Application of the molding gels should be done in a dry environment to prevent surface bubbling. Care should be taken to scrape sides of mixing container while stirring components to insure no unmixed material remains. Clean up should be done with solvents such as mineral spirits, Methyl Ethyl Ketone (M.E.K.), or acetone solvents.  Both InstaGel and UraGel contain no V.O.C. solvents and are nonflammable, low odor products and classified as nonhazardous for shipping purposes.  See material safety information for complete information.

InstaGel is a flexible, brush-on product for making rubber molds from objects or wall surfaces which cannot be placed in standard box molds (any 3 dimensional objects or vertical wall surface). After mixing, InstaGel® thickens to a creamy spread-able gel which can be brushed onto vertical or overhead surfaces without sagging, or running. Within 24-hours InstaGel® cures to a tough rubber mold.  Before applying InstaGel®, surfaces should be coated with silicone or wax mold release and must be free of moisture to prevent unwanted bonding or surface bubbling. Mold releasing agents must be used to insure easy removal of InstaGel® rubber mold from the master.

UraGel 770 is a rigid (75 shore D) brush-on mother mold making material or low odor fiberglass replacement product. UraGel 770 is also used for manufacturing in-mold hard parts, reproduction ancient amour and decorative masks. Use this product any time you need to make hard durable parts from a large open faced mold.

UraGel 770™ is formulated for casting hard mother back-up molds or hard plastic parts. It can be brushed into rubber molds 1/2-inch thick in a single application. When fully cured UraGel 770™ forms a rigid “fiberglass like” polymer which is easily sanded or machined and painted to final form. UraGel 770™ is recommended as a rigid Mother mold back up for flexible InstaGel molds. Polyester fabrics and chopped fibers can be used with these materials to enhance strength and durability. UraGel 770’s thick gel consistency makes it easier to work with than fiberglass, no cloth lay-up required. Very thick sections can be created in a single product application, no fumes or odor.

Procedure for making a brush-on mold from textured or carved wall surface or clay master;

1. Apply appropriate mold releasing agent (silicone spray, furniture paste wax) to surface.

2. Brush apply InstaGel to entire wall area at the desired thickness (1/4″ to 1/2″ thickness). Allow to cure overnight before beginning step 3.

3. Apply appropriate mold releasing agent over the InstaGel 40® (silicone spray or furniture paste wax).

4. Apply UraGel 770™ at the desired thickness (1/4″ to 1/2″ thickness) over the cured InstaGel 40® and allow 24 hours cure.

After 24 hours remove the InstaGel rubber mold and the UraGel 770™ back up mold from the surface. When you are ready to cast reproductions of the part lay the InstaGel rubber mold into the rigid UraGel 770™ cradle back up mold. Reproductions of the wall surface can be made by applying urethane, plaster or concrete into your finished mold. The rigid back up mold will help your rubber mold maintain the proper shape when it is placed on the floor and filled with casting material. Always use mold appropriate release agents to prevent unwanted bonding of parts to your new rubber mold. Your mold will allow you to reproduce the exact shape and texture of the original wall surface from a variety of materials.

Other Uses

InstaGel 40® and UraGel 770 can be used as a bonding adhesive for wood, fiberglass, flexible foam, rigid foam and masonry components. Its paste consistency fills large surface gaps and holds pieces together, but hardens slowly enough to permit bonded parts to be fitted or adjusted while curing.  These products will not dissolve EPS foams or styrene foams.

InstaGel 40® bonds well to other materials and its 2-hour set time makes it an excellent flexible bonding adhesive for foam, wood or masonry production line assembly.

UraGel 770™ is also used as adhesive, surface filler and hard coating over expanded polystyrene (E.P.S.) foam.

UraGel 770™ can be painted with solvent base or water base paints (see Helpful Product Tips below). UraGel 770™ bonds well to other urethane materials and its 2-hour set time makes it an excellent rigid bonding adhesive for foam, wood or masonry production line assembly.

Helpful Product Tips

It is easier to lift a paint job out of a silicone rubber mold than to later try and paint over cured urethanes. When customers use UraGel 770 to make reproduction ancient suits of armor or shields or masks they usually apply paint or primer inside the silicone rubber mold first before brushing in UraGel 770.  When the UraGel 770 cures it will completely remove the paint layer from the mold, so your part comes directly out of your mold with a perfect paint job or primer layer.  This trick works best with solvent based paints or primers.  Water based paints will make the UraGel 770 bubble or foam as it cures in the mold.  For this procedure we recommend using solvent based aerosol spray can paints from the local hardware store. Allow aerosol spray paint to fully dry or speed drying with heat gun.  When paint is dry apply UraGel 770 into mold and allow full curing.  When the cured UraGel 770 part is removed from the mold it will lift paint layer from mold and have a perfectly painted or primed surface. This in mold painting method saves time, produces better looking smother finish and is more durable and scratch resistant than ordinary painting.

When making brush-on rubber molds from wood, concrete, plaster, water based clays or natural stone, extreme care must be taken to prevent sticking of InstaGel to master.  Moisture coming out of wood, concrete or plaster will cause bubbles in your rubber mold and make spray-on silicone based release agents fail.  You should paint or seal these materials and use heavier wax type release agents to prevent sticking of Instagel molding rubber.  When making brush-on molds paint or seal with a fast drying solvent based paint or sealer, let dry then use Johnson’s furniture paste wax or mold release wax to prevent sticking. Do not use car wax or liquid waxes because they usually contain water.  Furniture wax or purpose manufactured mold release wax does not contain water.

Mixing Instructions

Have all materials at 70° – 85°F before mixing. Mix A and B components together in the proper portions (see chart below). Mix thoroughly for 1 minute.  While mixing, periodically scrape material off container sides to ensure proper blend. Do not over mix the material as this will reduce the viscosity of gels and cause them to become too thin. Avoid whipping air into the solution. If you are mixing quantities of ten pounds or more, we recommend using a mixing attachment (Jiffy® mixer) on an electric drill. Care should be taken to stop and scrape sides of mixing container with spatula if using an electric drill. Close containers tightly after use, liquid components of polyurethane can absorb atmospheric moisture when exposed to air.

Storage/Shelf Life

InstaGel and UraGel 770 liquids should be stored in the original, unopened containers in temperatures between 64°F and 86°F (18°C and 30°C). Shelf life of materials when kept in unopened, sealed containers at the recommended storage temperature is six months. Container should not be opened until ready for immediate use.

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