Catalogue

SMOOTH-ON Smooth-Cast 305 : 0.86kg – Medium Setting

Code: 47441

RM180.00

Quick Overview

Net Weight: 1.9lbs/0.86kgs

Read Technical Bulletin and MSDS before using available at:
https://www.smooth-on.com/products/smooth-cast-305/

In stock

Description

Mix Ratio 1A : 1B by volume or 100A : 90B by weight

The Smooth-Cast 300 Series of liquid plastics are ultra-low viscosity casting resins that yield castings that are bright white and virtually bubble free. Vacuum degassing is not necessary. They offer the convenience of a 1A:1B by volume or 100A:90B by weight mix ratio. The differences between them are pot life and demold time.

These resins readily accept fillers (such as URE-FIL 3 from Smooth-On) and can be colored with SO-Strong or Ignite color tints (Smooth-Cast 325 series accepts pigments better than the Smooth Cast 300 series). Fully cured castings are tough, durable, machinable and paintable. They resist moisture and mild solvents. Applications for Smooth-Cast 300 Series Liquid Plastics include reproducing small to medium size sculptures, making prototype models, special effect props and decorative jewelry.


Instructions

Safety – Materials should be stored and used in a warm environment (73° F / 23° C). These products have a limited shelf life and should be used as soon as possible. All liquid urethanes are moisture sensitive and will absorb atmospheric moisture. Mixing tools and containers should be clean and made of metal, glass or plastic. Mixing should be done in a well-ventilated area. Wear safety glasses, long sleeves and rubber gloves to minimize contamination risk.

Applying A Release Agent A release agent is necessary to facilitate demolding when casting into or over most surfaces. Use a release agent made specifically for mold making (Universal® Mold Release or Mann’s Ease Release® 200 available from Smooth-On or your Smooth-On distributor). A liberal coat of release agent should be applied onto all surfaces that will contact the plastic.

IMPORTANT: To ensure thorough coverage, apply release and brush with a soft brush over all surfaces. Follow with a light mist coating and let the release agent dry for 30 minutes. Smooth-On silicone rubber molds usually do not require a release agent unless casting silicone into the mold. Applying a release agent will prolong the life of the mold.


IMPORTANT: Shelf life of product is reduced after opening. Remaining product should be used as soon as possible. Immediately replacing the lids on both containers after dispensing product will help prolong the shelf life of the unused product. XTEND-IT® Dry Gas Blanket (available from Smooth-On) will significantly prolong the shelf life of unused liquid urethane products.


Measuring and Mixing Liquid urethanes are moisture sensitive and will absorb atmospheric moisture. Mixing tools and containers should be clean and made of metal, glass or plastic. Materials should be stored and used in a warm environment (73°F/23°C).

Stir or shake both Part A & Part B thoroughly before dispensing. After dispensing equal amounts of Parts A and B into mixing container (100A:90B by weight) and mix thoroughly.Stir deliberately making sure that you scrape the sides and bottom of the mixing container several times. Be careful not to splash low viscosity material out of the container.


Pouring Pour your mixture in a single spot at the lowest point of the containment field and let the mixture seek its level. This will help minimize air entrapment.

For Best Results – Best results are obtained using a pressure casting technique. After pouring the mixed compound, the entire casting assembly (mold, dam structure, etc.) is placed in a pressure chamber and subjected to 60 PSI (4.2 kg/cm2) air pressure for the full cure time of the material.

Curing – Important: Use this product with at least room size ventilation or in proximity to a forced outlet air vent and do not inhale/breath fumes. Fumes, which may be visible with a significant mass concentration, will quickly dissipate with adequate ventilation. Castings with significant mass may be hot to the touch and irritate skin immediately following cure. Let casting cool to room temperature before handling.

Demold time of the finished casting depends on mass and mold configuration. Low mass or thin-walled castings will take longer to cure than castings with higher mass concentration. Smooth-Cast® 305 will cure in 30 – 40 minutes (Smooth-Cast® 300 in 7 -10 minutes and Smooth-Cast® 310 in 2 – 4 hours) depending on mass and mold configuration.

If making rotational or hollow castings, backfilling with a rigid foam (Foam-iT!® 5 or other) will provide lightweight reinforcement. Foam backfilling is recommended if castings will be subjected to temperatures above 85°F / 30°C.

Post Cure Castings will reach “full cure” faster and achieve maximum physical properties if post cured. Allow material to cure for recommended Cure Time at room temperature followed by 4 – 6 hours at 150°F/65°C. Allow casting to come to room temperature before handling.

Performance Cured castings are rigid and durable. They resist moisture, moderate heat, solvents, dilute acids and can be machined, primed/ painted or bonded to other surfaces (any release agent must be removed). If machining cured material, wear dust mask or other apparatus to prevent inhalation of residual particles. Castings can be displayed outdoors after priming and painting. Unpainted castings will yellow over time – more quickly when exposed to ultra-violet light.

Because no two applications are quite the same, a small test application to determine suitability is recommended if performance of this material is in question.


Data At-A-Glance

Mix Ratio By Volume 1A:1B
Mix Ratio By Weight 100A:90B
Specific Gravity 1.05 g/cc
Specific Volume 26.4 cu. in./lb.
Color White
Pot Life 7 minutes
Cure Time 30 minutes
Tensile Strength 3,000 psi
Elongation @ Break 7.5 %
Compressive Modulus 44,900 psi
Shrinkage 0.0065 in. / in.
Tensile Modulus 134,000 psi
Flexural Strength 4,000 psi
Flexural Modulus 118,000 psi
Compressive Strength 3,800 psi
Shore D Hardness 70
Heat Deflection Temp 120 °F
Mixed Viscosity 80 cps

 

 

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