Etching War Shields

Purpose:

Document method to acid etch aluminum war shields.

Scope:

The topics covered are limited to surface preparation, design application, etchant, and final cleaning. Although this is primarily written to support war shield etching, the same good practices are universally used to etch aluminum products.

Materials:

Aluminum war shield
Successive sand paper grits and polishing compounds
Running water
Laundry box sized baking soda
2 gallons 30% hydrochloric acid, also known as muriatic acid
rubber gloves
protective clothing
goggles
large clean spray bottle, garden style
Non-metallic basin larger than the shield
Large non-metallic paint brush
contact paper and fast drying lacquer
black felt marker
Exacto knife
Pattern
Acetone
pH indicator
Dishwashing liquid

Procedure:

Allow one full day for etching a war shield

The etching process generates heat; monitor the temperature to avoid pattern damage

Keep a bucket of clean standing water nearby for use in case of accidental contact with acid

Grind all weld marks and shape cut edges to remove burrs

Sand the surface to 800 grit or better

Compound polish to near mirror finish

Wash polished surface with dishwashing liquid

Rinse completely

Dry thoroughly using a lint free towel

Draw the pattern onto the contact paper

For a copy of the Raven, go to the Files page

Remove the backing and apply the contact paper to the aluminum

Push out air bubbles

Using the Exacto knife, cut the pattern

Remove the contact paper from the area to be etched

Remove sticky residue from the area to be etched. Use acetone as required

Use additional contact paper to seal edges and back of shield

Carefully examine the work and make repairs as needed using fast drying lacquer

Carefully read and understand the Safety Instructions for hydrochloric acid located on the label

Keep the baking soda in close proximity, it may be used to neutralize spills

Put on protective gear

Fill the spray bottle half full with water

In a well ventilated area, add muriatic acid to bottle of water to full mark

Replace the spray attachment and turn the knob close to ‘stream’

Place the shield in non-metallic basin

Saturate the shield surface with several streams from the spray bottle

Do not breathe the fumes

Lightly use the brush bristles to even the acid solution

Allow the etching to being slowly and evenly. A black residue indicates reaction occurring

Rinse the surface with water and examine for errors in the pattern

Correct pattern areas. Fast drying lacquer may be used to patch the patterned area

Re-saturate the surface continually with etchant until the desired depth is achieved

When temperature becomes excessive, perform an intermediate rinse and dilute etch solution with water

Continue etching to completion

Rinse the shield completely

Remove shield from basin and dry etched area immediately to mitigate water spotting

Remove contact paper pattern

Clean sticky residue with acetone

Neutralize waste water by adding baking soda

Check for neutral pH and dispose waste in accordance with label instructions

Gently clean shield surface with dishwashing liquid, rinse, and dry

Shield is now ready for next assembly level

Last Updated 2012.05.15 07:00 EST

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