Epoxy Adhesive

2216 B/A

Surface Preparation

(continued)

Aluminum (Chemical Etch)

Aluminum alloys may be chemically cleaned and etched as per ASTM D 2651. This

procedure states to:

1. Alkaline Degrease – Oakite 164 solution (9-11 oz/gal of water) at 190°F ± 10°F

(88°C ± 5°C) for 10-20 minutes. Rinse immediately in large quantities of cold

running water.

2. Optimized FPL Etch Solution (1 liter):

Material

Amount

Distilled Water

700 ml plus balance of liter (see below)

Sodium Dichromate

28 to 67.3 grams

Sulfuric Acid

287.9 to 310.0 grams

Aluminum Chips

1.5 grams/liter of mixed solution

To prepare 1 liter of this solution, dissolve sodium dichromate in 700 ml of

distilled water. Add sulfuric acid and mix well. Add additional distilled water to

fill to 1 liter. Heat mixed solution to 66 to 71°C (150 to 160°F). Dissolve 1.5

grams of 2024 bare aluminum chips per liter of mixed solution. Gentle agitation

will help aluminum dissolve in about 24 hours.

To etch aluminum panels, place them in FPL etch solution heated to 66 to 71°C

(150 to 160°F). Panels should soak for 12 to 15 minutes.

3. Rinse: Rinse panels in clear running tap water.

4. Dry: Air dry 15 minutes; force dry 10 minutes (minimum) at 140°F (60°C)

maximum.

5. If primer is to be used, it should be applied within 4 hours after surface

preparation.

Plastics/Rubber

1. Wipe with isopropyl alcohol.*

2. Abrade using fine grit abrasives (180 grit or finer).

3. Wipe with isopropyl alcohol.*

Glass

1. Solvent wipe surface using acetone or MEK.*

2. Apply a thin coating (0.0001 in. or less) of 3M™ Scotch-Weld™ Structural

Adhesive Primer EC-3901 to the glass surfaces to be bonded and allow the primer

to dry a minimum of 30 minutes @ 75°F (24°C) before bonding.

*When using solvents, extinguish all ignition sources, including pilot lights, and

follow the manufacturer’s precautions and directions for use. Use solvents in

accordance with local regulations.

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