Covering Rack Rash

Brushed black anodised Aluminium is always vulnerable to dings and scratches because the underlying metal is soft, otherwise the surface is durable.


This idea shows a way of covering deep scratches on brushed anodised aluminium panels. It matches the same colour of black by using aerosol “Acid Etch Primer” that is normally used as a preparation coat for Aluminum before painting.

  • Acid Etch Primer
  • Plastic cup with a lid
  • Fine pointy brush
  • Strand of a regular horse hair painting brush

The use of an aerosol acid etch primer means that the paint itself is very thin and evaporates easily. Acid etch paint cuts into the Aluminum oxide layer and helps to turn it black. The plastic cup is used to hold the paint and the lid is replaced after applying paint to the brush so that it doesn’t dry out or gas you!

After application, if an error is made, the paint can be brushed off immediately but this is best avoided, especially on the front panel. Aerosol paint is very thin so thickly applied areas usually dry to a thin layer. In some areas it will be necessary to reapply a coat.

Practice Run

The first test is with a concealed part of a Rack Ear, in the picture below, the damage on the ear is extensive.


The fine brush is used to apply the paint, a steady hand is needed.


The end result after a few moments to dry is as shown below. The scratch is nicely concealed and surrounding brushed areas are not affected or filled too much.


Complex Scratches

The next area to tackle was a very deep complex set of scratches on the top of the panel. Large gouges were painted with a brush and then whilst the paint was wet, the strand of horse hair was used to push the paint into the narrower scratches.


Pits & Dings

The “ding” was less successful as it was very deep and had edge profiles. This could maybe have been better dealt with by using a pin to apply the paint into the centre then the horse hair used to push it out to edges. 


Overall result

It seems a pretty good way of covering rack rash if you have the patience and steady hand.



Copyright © 2020 Super Synth Projects, Guy Wilkinson