CHO-SHIELD
®
4994 is a smooth, highly
conductive flexible silver-filled polyurethane
coating designed for military/aerospace
airframe applications.
The coating provides superior adhesion,
excellent solvent rub and wear resistance,
and is resistant to numerous operational
and environmental fluids.
CHO-SHIELD 4994 can be applied to
aluminum as well as non-conductive
substrates and is designed to be used with
primers and with external topcoat systems.
ELECTRICALL CONDUCTIVE SILVER
POLYURETHENE COATING FOR AIRFRAMES
CHO-SHIELD
®
4994
Customer Value Proposition:
Product Features:
• Superior conductivity, flexibility and
fluid resistance.
• CHO-SHIELD 4994: 3 hour pot life
with 7 day full cure under ambient
conditions.
• Coating can be cured under heat
accelerated conditions within 4
hours.
• Designed for application by standard
high volume low pressure spray
equipment.
Application
Clean the substrate:
The substrate should be clean, dry and
free of oils, release agents, dirt and lint.
Clean aluminum surfaces with methyl ethyl
ketone (MEK) or isopropyl alcohol / ethanol
for solvent sensitive substrates. Let the
substrate air dry for 15 minutes
Mix the material:
Mix the CHO-SHIELD 4994 coating in this
order: Combine Part C and Part D to Part A
using the weight ratios given in Table 1 and
mix. Shake on a paint shaker until uniformly
dispersed, which can take up to 30 minutes
depending on the type of paint shaker. Do not
shake the paint so much that it gets warm
or hot. Check for the homogeneity of the
mixture by feeling the sides and bottom of
the container with a spatula to assure all the
filler and resin are well dispersed.
Add the Part B using the weight ratios given
in Table 1 and shake / mix for an additional 3
minutes.
Contact Information:
Parker Hannifin Corporation
Chomerics Division
77 Dragon Court
Woburn, MA 01801
phone 781 935 4850
fax 781 933 4318
chomailbox@parker.com
www.chomerics.com
www.parker.com/chomerics
Typical Properties Method**
CHO-SHIELD
®
4994
Typical Values
Resin - Polyurethane
Filler - Silver
Color - Metallic Light Brown
Shielding Effectiveness Modified Chomerics TP-08 (Q) > 85 dB (200 - 10,000 MHz)
Surface Resistance (max.) at 3 mil CEPS-0002 (Q/C)
< .075
ohms / square
Adhesion ASTM D3359 (Q/C) 5B
Specific Gravity (ASTM D792) 2.3 g/mL
Mix Ratio by Weight - (Part A : Part B : Part C : Part D) 100 : 18.3 : 1.4 : 20.9
Recommended Cure Schedules -
Cure Cycle Option 1: 2 Hours @ Standard Conditions + 2 hrs @ 54ºC
(130ºF)
Cure Cycle Option 2: 7 Days @ Standard Conditions 16-21ºC (60-70ºF)
40-60% RH
Recommended Dry Film Thickness (DFT) - 3.00 - 4.00 mil
Continuous Use Temperature (Q) -40°C to 85°C (-40°F to + 185°F)
Shelf Life at 70°F (21°C) (Q) 6 Months From Date of Manufacture
Theoretical coverage , 3 mils ASTM D2697 (Q) 0.030 ft
2
/gram; 0.009m
2
/gram; 259 ft
2
/gallon
Calculated VOC
(Less H
2
O and Exempt Solvents)
USEPA Method 24 (Q) 596 g/L
Wet Density ASTM D1475 (Q/C) 2.1 (g/cc)
Pot Life ASTM D4212 (Q/C) 3.0 Hours
Solvent Rub Resistance CHO-TM 95-40-6013 (Q/C) Pass
Wear Resistance (Taber) ASTM D4060 (Q) Wear Index: 0.160 (mg/cycle); Wear Cycles per mil: 1000
Pencil Hardness ASTM D3363 (Q) Scratch : 4H; Gouge: 2H
Impact Testing, Aluminum ASTM D2794 (Q) Intrusion: >75 (ft/lb) / Extrusion: >75 (ft/lb)
Mandrel Bend, Aluminum ASTM D522 - Test Method B (Q) > 500%
Conical Bend, Aluminum ASTM D522 - Test Method A (Q) Elongation: ≥ 32.0% / Cracking: No Evidence
Surface Resistance, Aluminum CEPS-0002 (Q) 185ºF 14 days; -40ºF 14 days; 185ºF 85%RH 30 Days: < .075 (Ω/Sq.)
Cross Hatch Adhesion, Aluminum ASTM D3359 (Q) 5B
Visual Inspection, Aluminum (Q) Pass
Surface Resistance,
Aluminum and Composite
CEPS-0002 (Q)
MIL-T-5624 JP-8 14 Days @ 72ºF; MIL-H-5606 Hydraulic Fluid 7 Days @
160ºFl; MIL-L-7808 Lubricating Oil 7 Days @ 160ºF: < .075 (Ω/Sq.)
Cross Hatch Adhesion,
Aluminum and Composite
CHO-TM 95-40-6013 (Q) Pass
Visual Inspection, Aluminum and Composite Q Pass
Table 1
Ordering Information
Product Weight (grams) Packaging Chomerics Part No. Primer Included
CHO-SHIELD
®
4994
1802 4 component, 1 quart aluminum can kit 52-04-4994-1000 Not Required
7210 4 component, 1 gallon aluminum can kit 52-03-4994-1000 Not Required
ENGINEERING YOUR SUCCESS.
Chomerics
CHOMERICS and CHO-SHIELD are registered trademarks of Parker Hannin Corporation. © 2007-2013
www.chomerics.com
www.parker.com/chomerics
TB 1032 EN July 2013 Rev A
The user, through its own analysis and testing, is solely responsible for making the final selection of the system and components and assuring that all performance, endurance, maintenance, safety and
warning requirements of the application are met. The user must analyze all aspects of the application, follow applicable industry standards, and follow the information concerning the product in the
current product catalog and in any other materials provided from Parker or its subsidiaries or authorized distributors.
CHO-SHIELD 4994 - Product Information
Notes: N/A – Not Applicable, (Q/C) - Qualification and Conformance Test, (Q) - Qualification Test, the above properties are based on Cure Cycle 1.