[Antennas] Re: Cleaning Aluminum

2002年10月31日 07:59:41 -0600

"Barry L. Ornitz" wrote:
> =

> And this brings up an alternative way of cleaning the
> aluminum. In many cases you will find a Scothbrite=AE pad
> faster and easier to use to clean the entire piece. At home
> repair and paint stores, they sell different varieties for
> coarse, medium, and fine grit. The ones sold in the grocery
> stores usually work fine and are cheaper.

Cleaning a heavy layer of oxide off elements of a DB420 (small folded
dipoles at UHF) wouldnt work with Scotchbrite....I tried...couldnt
get into all the nooks and crannys....
> The ultimate protection is generally to have the piece
> anodized. This is an electrolytic surface oxidation process

Agreed....but the cost is somewhat prohibitive for amateurs!
> I always recommend avoiding anything containing significant
> amounts of hydrofluoric acid as Mike, AC5P, suggested.

Actually it was I who suggested it...not Mike...
> Caustic or acidic HVAC coil cleaners have gone out of favor
> because they dissolve too much of the aluminum in the cleaning

Well this was almost 10 years ago when I did it...I didnt find
any of the aluminum being dissolved though...only the oxide..
perhaps because it was CAKED on....and I did dillute the solution
to a mild strength (I HAD been tempted to use it full strength!)
> process. The modern cleaners are much more mild, attacking
> mainly dirt. They also contain biocides to inhibit
> mold/mildew/algae growth. The older acidic cleaners contained
> as much as 20 percent hydrofluoric acid.
> =

> Believe me, you do NOT want to mess with hydrofluoric acid.
> It causes extremely painful burns, and if your skin absorbs
> enough of it, you die - medical treatment only treats the
> pain. If you do not get a lethal dose, the burns are quite
> painful and they do not heal for months (and sometimes they
> never heal properly). I am amazed that this stuff is still
> allowed to be sold except to a skilled licensed user.

I bought it at a local chemical outlet....I guess because I worked
at the local power utility at the time, they figured I knew what I
was doing with it! (fooled them!!! hehehee ok, kidding!) With the
acid dilluted, I had no problems with it....the bottle was plastic
and later on did develop a leak (thanks to a holesaw that rubbed =
up against it and slowly nawwed a small pinhole in it)..it was
a year later when I found the bottle more than half empty..the =
slow release had been into a box holding the bottle....and luckily
it absorbed most of it...I had a little clean up thanks to the rug
underneath it...a little Arm and Hammer took care of it..
having been around Lead-antimony batteries at work and seeing
what lightning does to them...and a microwave station rack
after the strike!!.....I have had plenty of experience in clean up..
I must admit CAUTION and extreme care is the order of business
with ANY acid...no matter how strong or weak...
BUT if there are better cleaners out there (both environmentally
and from a handling point of view) by all means, I would endorse
their use...I just speak from experience with my cleaning of 4
DB420s that brought all of them back to like new condition..
and believe me, they WERENT when I got them :)
Chris
WB5ITT