[ARC5] Crystal aging and "Rust Remover"

[Dennis Monticelli]

My experience with ammonium biflouride crystals (which make a buffered HF
solution) is that you want to end up with (via proper concentration and
temp of solution) an etch rate of about 100Hz/min without the need for
agitation.  I have found a reduction in activity for movement of 40M rocks
beyond about 25KHz.  I suspect rounding of the edges is the culprit.
 Theoretically, one could correct this with some edge grinding but I have
not tried that as I don't have any grinding compound.  Another thing to
watch out for when etching is to find a way to distribute the solution
uniformly around the blank.  Because the blank must be touched in some
manner by a support, that is not easy.

I have moved about a couple of dozen rocks, all but one successfully.
Most of the movements have been less than 10KHz.   As a novice I once moved
a 40M rock with Whink nearly 200KHz.  It worked but it ended up my most
sluggish performer.

Dennis AE6C

On Fri, Mar 15, 2013 at 12:20 PM, Kenneth G. Gordon <
kgordon2006 at frontier.com> wrote:

> On 15 Mar 2013 at 9:47, Bruce Long wrote:
>
> > Sorry Kennth for sending this email originally just to you instead of
> > the group   bruce
>
> Not a problem for me, Bruce.
>
> I do know that ALL of us here are very interested in your experiences.
>
> > with respect to HF  I discovered to my surprise some small bottles of
> rust
> > removing potions available at the big orange box are actually dilute
> > HF solutions.  They work really well for me.
>
> I just went to check the two bottles of "Rust Remover" we have here: the
> trade name for that stuff, as I have mentioned here before is "WHINK", in
> very small letters near the top. The bottles are brown plastic and fairly
> small.
>
> Very clearly written in large letters near the bottom are the words
> "CONTAINS HYDROFLOURIC ACID."
>
> I am very interested in your words above, "They work really well for me."
>
> Would you be so kind as to explain in some detail how you use this stuff,
> and
> what are the results you have gotten with it?
>
> Like, how fast and how well it actually moves the crystals, etc?
>
> I suppose you use plastic or wooden tools (tweezers, etc.) with it?
>
> I know from my own experience with WHINK, that it does a really marvelous
> job of cleaning crystals, and I have used it a time or two in the past to
> reactivate sluggish crystals.
>
> But I have yet to use it to move any of the bunch of FT-243s I bought some
> time ago to any ham bands.
>
> I had thought that in order to get the crystals to move, some pretty far, I
> would need to grind them first, THEN use the "Whink".
>
> If I can avoid the grinding process, with its attendant issues of
> difficulty with
> cleanliness, and difficulty with keeping the sides of the crystal blank
> parallel
> (which is extremely difficult to accomplish when grinding by hand), I
> would be
> very pleased.
>
> I do have some very, very good grinding compound which a ham of my
> aquaintance sent me some time ago, but I have hesitated to use it.
>
> Lastly, I wonder if there is a non-dangerous way that we amateurs can
> "distill" the WHINK to get a stronger solution of HF from it?
>
> I would certainly hesitate to boil it. I don't know what its temperature of
> evaporation might be, nor do I know what the other ingredients in WHINK
> actually are. I suppose we can find out.
>
> However, WHINK may work well enough as it is that we don't have to bother
> with "strengthening" it.
>
> Ken Gordon W7EKB
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