[R-390] Alodine and hexavalent chromium

[N4BUQ at aol.com]

The reason I wanted to wet-sand the pieces is they weren't in really great shape.  Scratches, small oxidized patches, etc., made me want to get them in physically better condition before any surface finishes.

The center shelf seemed to have a rough texture about it that I wasn't sure would come out if just chemically stripped.  I got a lot of the old finish off and it went down the sink.  I assume there wasn't enough of anything in that to be a hazard.  As someone else mentioned, once it has dried and done its thing, it isn't as hazardous as when in liquid form.

As I said, the local place is quite reasonable and I'd rather someone do it right than have me messing it up on top of creating a potential biohazard.  There's a lot of things I can do, but some things I'd just rather leave to the pros.

You mention you did a back panel.  Did the process destroy the lettering?  I assume it did.  What did you (if anything) about that?

Thanks to all for the kind responses and advice.

Barry(III) - N4BUQ

>After Alodine is applied and dried I believe it's totally safe (as long as
>you don't eat it). It is commonly used as a surface finish on all kinds of
>aluminum parts or as a surface prep for painted aluminum to increase paint
>adhesion, like on the R-39x dial bezel. It is a very, very thin coating,
>usually 0.5 to 3 thousands of an inch, and is easily removed by sanding or
>by phosphoric acid metal prep solution or a lye bath as Hank suggested.
>
>If you are sending your pieces to an Alodiner are you sure you need to
>remove what's already there?; they will probably throw the parts in an acid
>bath first thing.
>
>It IS something you can do at home, but aside from the cost of buying a
>gallon and having it shipped, you need to practice a bit to get the coating
>to be uniform and the correct thickness to match the other parts. (longer
>soak or brushing = heavier coat = darker color). If you screw up the part
>you can always throw it back in the lye bath and start over :^)  I've done
>the R-390 IF coil cans, dial bezels, and a back panel with good results, but
>it's not something I'd want to do frequently.
>
>For *small* quantities of the stuff that are used for home projects I
>wouldn't worry about disposal issues, but please don't throw the used stuff
>on the ground. You definitely want to wear gloves to protect your skin (and
>to keep hand oils off the prepped part), and it can permanently stain
>anything it touches.
>
>John
>
>----- Original Message ----- 
>From: <N4BUQ at aol.com>
>To: <R-390 at mailman.qth.net>
>Sent: Thursday, January 13, 2005 11:48 AM
>Subject: [R-390] Alodine and hexavalent chromium
>
>
>> I've been doing a bit more looking into getting the panels for my R390A's
>re-alodined.  Turns out this stuff is hazardous as it contains hexavalent
>chromium (chrome?).  Around here, you have to dispose of this stuff properly
>so I might not be trying this at home after all.  Fortunately I've found a
>place that will do the lot of parts for a reasonable price.
>>
>> This got me to wondering how hazardous it is to remove this coating.  Is
>it safe to wet-sand the parts to remove the old coating?  Is the amount of
>coating removed so small that it is insignificant?
>>
>> Just wondering...
>>
>> Barry - N4BUQ
>> _____________________________________________________________
>> Win a new Icom IC-756PROIII and help QSL/QTH.net
>> Details at: http://mailman.qth.net/index.html
>> _____________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/faq.htm
>> Post: mailto:R-390 at mailman.qth.net
>> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>>
>
>
>_____________________________________________________________
>Win a new Icom IC-756PROIII and help QSL/QTH.net
>Details at: http://mailman.qth.net/index.html
>_____________________________________________________________
>R-390 mailing list
>Home: http://mailman.qth.net/mailman/listinfo/r-390
>Help: http://mailman.qth.net/faq.htm
>Post: mailto:R-390 at mailman.qth.net
>Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>