PROTAVIC Metrethane 4757 is a part of a new class of PROTAVIC flexible urethane elastomers specifically designed for demanding electronic applications. Metrethane 4757 is a two-component, low viscosity system that provides excellent protection of electronic components ranging from transducers, sensors, load cells, delicate magnetic coils and bobbins to power supply applications where low inductance drop after potting is required.

Should not be used for specification purposes

Composition Urethane resin
Color Translucent/Opaque or Any requested
Mixed Viscosity Brookfield #3 spindle (25ºC), centipoise


Product 20 RPM 50 RPM
4758 6,000 1,820


Specific Gravity 0.978
Flash Point, Activator, ºC 93 (200º F)
Flash Point, Base, ºC 204 (400ºF)
Working Life, 100 grams 0.5 hours
Shelf Life x 0.6 months
Mix ratio, parts by weight, base:activator 1: 3 1:4
Mix ratio, parts by volume, base:activator 1: 4 1:5

Cured Resin Properties

Tensile Strength, psi 500
Lap shear Strength, psi Aluminum to Aluminum 100-400
Elongation at Break, % 130
Hardness (Shore A) 50 +/-5
Glass Transition Temp. Tg -70ºC (-94ºF)
Volume Resistivity 5.0 X 1013 ohms-cm
Dielectric Constant, 1MHz 3.4
Dielectric Strength 400 volts/mil
Operating Temperature ºC -70 to 125

• Quick cure at common processing temps.
• Can be designed with any color
• Low-cost replacement for silicone RTV
• Excellent damping properties
• Superior thermal cycle/shock properties
• Protects components from internal stresses
• Prevents inductance drop after potting

Recommended Cure Time to Reach Handling

Hours Temp. ºC Temp ºF
2 hrs 65 150
24 hrs 25 77

For ultimate properties cure 6 hours at 65°C or allow to set at room temperature for 4 weeks.

Preparation of Mixture
For product purchased in two-component kits, mix the entire contents of Metrethane 4757 base and activator in their original shipping containers to a uniform consistency and color, each time, before dispensing. Take care to incorporate all material adhering to the bottom, sides and corners of the containers. Mechanical mixing of the components for two to three minutes is satisfactory. Measure only the approximate amount that can be applied in 0.5 hours. Blanket containers of unused base and activator with nitrogen prior to re-sealing for storage.

Air Removal
Air entrapment during mixing may be removed in vacuum (5 mm of mercury). The holding container should be no more than one-third full. Allow the mixture to foam and then subside. Maintain the low pressure for several more minutes, at which point most of the large bubbles will have broken.

The material can be poured in the required thickness after which the parts are set aside to cure using the recommended cure schedules listed on the first page.

HANDLING PROTAVIC Metrethane 4757 is a blend of urethane resins and curing agents. Keep stored in the original container at temperatures from 0oC to25oC. The product is uniform when packaged.Read material safety data sheets before handling. Keep containers closed when not in use. Effective ventilation is necessary. Goggles, gloves and protective clothing should be worn during handling or exposure. Refer to the product MSDS for more information.

Availability and Order Information
Metrethane 4757 is available as a two-component kit consisting of separate containers of urethane resin and curing agent. Metrethane 4757 is available in pint, quart, one gallon, and five gallon kits.

Packaging Sizes & Types
Pints, Quarts, Gallons, 5 Gallons, 55 Gallon Drums

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Ordering Information
When ordering, specify the name, number, letter designation, color, quantity, container size and packaging form. The order should be placed with the PROTAVIC order entry department. The minimum order size is $100.00. Evaluation kits are available for $40.00. The $ 40.00 fee will be credited against the first order for the product.