[R-390] White lines on knobs and more

[John Gedde]

The whole idea is to get the surface coating of aluminum oxide off.  For the knobs, I bead blasted them.  For panels and what not, scotch brite followed by a quick dip in diluted metal “prep and etch” available from Home Depot.  

 

The coating I speak of is what Collins et al used for a surface treatment on unpainted aluminim like chassis panels, the Utah plate, etc.  So, getting up to speed with Bonderite gives you not only the ability to prime for painting but to restore coated parts in the radio as well.  I have done several unpainted panels and covers on my radios using this method.  I used scotch brite brushed in one direction carefully to clean off the old conversion coating the OEM put on and also to duplicate the brushed finish they had originally.

 

I’ve attached a pic of my R390 inside.  All the covers shown have been restored using this method…

 

John

 

From: Larry H <larry41gm at gmail.com> 
Sent: Saturday, September 7, 2019 5:47 PM
To: John Gedde <jgedde at optonline.net>
Cc: R-390 Forum <r-390 at mailman.qth.net>
Subject: Re: [R-390] White lines on knobs and more

 

Thanks John,  Good to know about your new method.  I was wondering, how do you clean and deoxidize the aluminum in prep for the dip? 

 

Regards, Larry

 

On Sat, Sep 7, 2019 at 9:52 AM John Gedde <jgedde at optonline.net <mailto:jgedde at optonline.net> > wrote:

Hi Larry,

It looks great!  I have moved away from using a spray primer on aluminum prior to paint in favor of a chromate conversion coating.  Loctite Bonderite is what I use.  It's what we use at work for spaceborne mechanisms that get painted or aluminum surfaces that remain bare (non-anodized).  I've never had any issues with adhesion using this stuff.  Basically you clean and deoxidize the aluminum, dip it in Bonderite for a minute or so, rinse and let dry.  The aluminum turns a golden color and paint readily adheres to it if you spray within 24 hours.  The coating is also known by other names: ChemFilm, Alodyne, Iridite, etc.

John

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