[R-390] White lines on knobs and more

[Larry H]

Thank you, John, for the nice explanation.  Your R-390 panels look very
nice.

Question - would sanding the knobs remove the oxide well enough?  Is there
an easy way to tell if the oxide has been removed?

Regards, Larry

On Wed, Sep 11, 2019 at 1:53 PM John Gedde <jgedde at optonline.net> wrote:

> 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> 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
>
>