3
Scotch-Weld
Epoxy Adhesive
Technical Data
TM
1838 B/A Green
•
1838 B/A Tan
•
1838-L B/A Translucent
February, 2016
Product Description
• 3M
TM
Scotch-Weld
TM
Epoxy Adhesives 1838 B/A Green and Tan are controlled flow
products; Scotch-Weld 1838-L B/A Translucent Adhesive is flowable.
• These epoxy adhesives are two-part, room temperature curing structural adhesives with
high shear strengths and excellent environmental resistance.
• Excellent for bonding many metals, woods, rubbers and some plastics.
Typical Uncured
Physical Properties
Note: The following technical information and data should be considered representative or
typical only and should not be used for specification purposes.
Product
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Green
Base
Accelerator
Base
Accelerator
Base
Accelerator
Base
Accelerator
By Weight
By Volume
Mixed 100 gms
70,000-600,000 cps
300,000-1,000,000 cps
3M™ Scotch-
Weld™
Epoxy
Adhesive
1838 B/A
Tan
100,000-600,000 cps
100,000-600,000 cps
3M™ Scotch-
Weld™
Epoxy
Adhesive
1838-L B/A
Translucent
11,000-15,000 cps
6,000-12,000 cps
Viscosity (approx).
@ 80°F (27°C)
Base
Color
Net Weight
lbs./gal.
Mix Ratio (B:A)
Worklife 73°F (23°C)
Modified Epoxy
Polyamide
White
Green
11.0-11.6
8.9-9.3
1:1
4:5
60 minutes
Modified Epoxy
Polyamide
Tan
Tan
9.1-9.5
7.5-8.0
1:1
5:6
60 minutes
Synthetic Resin
Modified Amine
Clear
Amber
9.4-9.8
8.1-8.5
6:5
1:1
60 minutes
3M
™
Scotch-Weld
™
Epoxy Adhesives
1838 B/A Green
•
1838 B/A Tan
•
1838-L B/A Translucent
Typical Cured
Physical Properties
Note: The following technical information and data should be considered representative
or typical only and should not be used for specification purposes.
Product
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Green
3M™ Scotch-
Weld™
Epoxy
Adhesive
1838 B/A
Tan
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838-
L B/A
Translucent
Color
Shore D Hardness
(Approx.)
Elongation (Approx.)
Ultimate Tensile
Modulus of Elasticity
Green
80-85
2-3%
4290 psi
344,000 psi
Tan
80-85
2-3%
—
—
Clear/Amber
80-85
3-7%
—
—
Typical Cured
Thermal Properties
Product
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Green
3M™ Scotch-
Weld™
Epoxy
Adhesive
1838 B/A
Tan
3M™ Scotch-
Weld™ Epoxy
Adhesive
1838-L B/A
Translucent
Thermal Conductivity
(Btu/Hr/Ft2/°F/Ft)
Coefficient of Thermal
Expansion (in/in/°C)
Glass Transition Temp.
.169
79 x 10
-6
Between 32-40°F
(0-40°C)
131°F (55°C)
—
—
—
—
.116
301 x 10
-6
Between 68-184°F
(20-120°C)
90°F (32°C)
Typical Cured
Electrical Properties
Product
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Green
3M™ Scotch-
Weld™
Epoxy
Adhesive
1838 B/A
Tan
3M™ Scotch-
Weld™ Epoxy
Adhesive
1838-L B/A
Translucent
Dielectric Strength
(Volts/MIL)
Volume Resistivity
@ 75°F (24°C) (ohms-cm)
Dissipation Factor
1 Khz @ 75°F (24°C)
Dielectric Constant
1 Khz @ 75°F (24°C)
585
1.5 x 10
15
.012
6.06
—
—
—
—
600
5.0 x 10
12
.088
6.1
-2-
3M
™
Scotch-Weld
™
Epoxy Adhesives
1838 B/A Green
•
1838 B/A Tan
•
1838-L B/A Translucent
Handling/Curing
Information
Directions for Use
1. For high strength structural bonds, paint, oxide films, oils, dust, mold release agents
and all other surface contaminants must be completely removed. The amount of
surface preparation directly depends on the user’s required bond strength and
environmental aging resistance. For suggested surface preparations on common
substrates, see the section on Surface Preparation.
2. These products consist of two parts. Mix thoroughly by weight or volume in
proportions specified on product label or in Typical Uncured Physical Properties
section below. Resulting color should be uniform. Properly reseal containers.
3. For maximum bond strength apply product evenly to both surfaces to be joined.
4. Application to the substrates should be made within 1 hour for 3M™ Scotch-
Weld™ Epoxy Adhesives 1838 B/A Green and Tan and 90 minutes for Scotch-
Weld 1838-L B/A adhesive. Larger quantities and/or higher temperatures will
reduce this working time.
5. Join the adhesive coated surfaces and allow to cure until completely firm.
Overnight curing @75°F (24°C) is usually sufficient. Heat, up to 200°F (100°C),
will speed curing.
6. The following times and temperatures will result in
handling strength
for these
products:
Temperature
Time
RT
6-10 hrs.
150°F (65°C)
15-20 mins.
7. The following times and temperatures will result in a
full cure
of these products:
Temperature
Time
75°F (24°C)
7 days
150°F (65°C)
2 hours
200°F (100°C)
30 minutes
8. Keep parts from moving during cure. Contact pressure is necessary. Maximum
shear strength is obtained with a 3-5 mil bond line.
Surface Preparation
The following cleaning methods are suggested for common surfaces.
Steel:
1. Wipe free of dust with oil-free solvent such as Methyl Ethyl Ketone (MEK).*
2. Sandblast or abrade using clean fine grit abrasives.
3. Wipe again with solvents to remove loose particles.
Aluminum:
1. Alkaline Degrease – Oakite 164 solution (9-11 oz./gallon water) at 190°F ± 10°F
(88°C ± 5°C) for 10-20 minutes. Rinse immediately in large quantities of cold
running water.
-3-
3M
™
Scotch-Weld
™
Epoxy Adhesives
1838 B/A Green
•
1838 B/A Tan
•
1838-L B/A Translucent
Surface Preparation
(continued)
2. Acid Etch – Place panels in the following solution for 10 minutes at 150°F ± 5°F
(66°C ± 2°C).*
Sodium Dichromate
Sulfuric Acid, 66°
2024-T3 aluminum (dissolved)
Tap Water as needed to balance
4.1 - 4.9 oz./gallon
38.5 - 41.5 oz./gallon
0.2 oz./gallon minimum
3. Rinse – Rinse panels in clear running tap water.
4. Dry – Air dry 15 minutes; force dry 10 minutes at 150°F ± 10°F (66°C ± 5°C).
5. If primer is to be used, it should be applied within 4 hours after surface
preparation.
Plastics:
1. Solvent wipe with Isopropyl Alcohol.*
2. Abrade using clean fine grit abrasives.
3. Solvent wipe with Isopropyl Alcohol.*
Rubbers:
1. Solvent wipe with MEK.*
2. Abrade using clean fine grit abrasives.
3. Solvent wipe with MEK.*
Glass:
1. Solvent wipe with acetone or MEK.*
For glass applications which will be subjected to high moisture/humidity
conditions, EC-3901 primer or equivalent should be used to prime the glass.
*Note:
When using solvents or chemicals, be sure to extinguish all ignition sources
and follow the manufacturer’s precautions and directions for use when
handling such materials.
Application and
Equipment Suggestions
These products may be applied with spatula, trowel, or flow equipment.
Two part mixing/proportioning/dispensing equipment is available for intermittent or
production line use. These systems are ideal because of their variable shot size and
flow rate characteristics and are adaptable to most applications.
-4-
3M
™
Scotch-Weld
™
Epoxy Adhesives
1838 B/A Green
•
1838 B/A Tan
•
1838-L B/A Translucent
Typical Performance
Characteristics
Note: The following technical information and data should be considered representative or
typical only and should not be used for specification purposes.
A. Aluminum Overlap Shear
Overlap shear strength was measured on FPL etched 1 in. wide by 1/2 in. overlap
specimens. The bonds were made from 2 panels of 4 in. x 7 in. x .063 in., 2024 T3
clad aluminum bonded together and cut into 1 in. wide specimens. The separation
rate of the testing jaws was .1 in./minute. Tests similar to ASTM D-1002.
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Green
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Tan
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838-
L B/A
Translucent
Test Temperature
-67°F (-55°C)
75°F (24°C)
180°F (82°C)
1500
3000
500
1500
2000
500
2000
2500
300
B. Aluminum T-Peel
T-Peel bonds were measured on 1 in. wide specimens cut from two FPL etched 8 in.
x 8 in. x .032 in., 2024 T3 clad aluminum panels bonded together. The separation
note of the testing jaws was 20 in./minute. Tests similar to ASTM D-1876
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Green
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838
B/A
Tan
3M™ Scotch-
Weld™ Epoxy
Adhesive 1838-
L B/A
Translucent
Test Temperature
-67°F (-55°C)
75°F (24°C)
180°F (82°C)
2
4
4
4
4
4
5
4
4
C. Cold Rolled Steel Overlap Shear
Note: The following data have been developed for 3M™ Scotch-Weld™ Epoxy Adhesive
1838 B/A Green; similar results would be expected for 3M™ Scotch-Weld™ Epoxy
Adhesive 1838 B/A Tan Adhesive and 3M™ Scotch-Weld™ Epoxy Adhesive 1838-
L B/A Translucent Adhesive.
Data are overlap shear on cold rolled steel (20 gauge), 302 stainless steel (50 mils
thick), and 2024 T3 clad aluminum (63 mils thick) in various environments after 365
days aging. All substrates were sandlbasted prior to bonding. Data are in psi and
tested at 75°F (24°C)
Cold Rolled
Steel
Control –
Scotch-Weld 1838 B/A Green Adhesive
Tap Water @ 75°F (24°C)
100% Relative Humidity at 120°F (49°C)
Hydraulic Oil (Mil-0-5606) @ 75°F (24°C)
White Gas @ 75°F (24°C)
2000-2200
1950
2200
2250
1100
Stainless
Steel
3400-3800
2750
1250
3600
3250
Aluminum
2400-2500
2250
1050
2900
2150
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