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Antique Radio Technical Forum

Posted by Frank Austin on 04/26/2007 14:56

:QUERSTION ?........as old Tech Sgt Terrell in my command used to say ..we all knew the diff...but he always put an R'uh sound to it....
:Does anyone still remember a product from the past called SAL-MET, housed in its typical soft metal "toothpaste" tube container, plus, it was about the same viscous consistancy of our current day gel types.
:Its introduction would have been dating from about the early '50's. Its use was for the occassional time when you would come against the situation of HAVING to solder aluminum, or at least get the aluminum tinned such that common copper wire interfacing could be made onto it.
:This was all very dependant upon the use of a healthy WELLER gun for the required heat capacity. This was accompanied with the secondary effect of creating one acrid odor along with a strong sizzle-spatter-frying noise.
:BUT.... it DID create a great tinning action for any further reworking.
:Now, with a SALMET sample, and my CE background, that would just be a matter of running a Gas Chromatography Analysis to precisely differentiate its elemental composition fingerprints and then a further delving for the determination of their proportions.
:With current experimentation, plus not having a S-M sample and not even finding a trace of the company's existance anymore, I am currently having an adequate result with the use of Oateys flux(no solder dust filler) that you can find at a HD or Lowes in its small tin.
:A MSDS check reveals its composition to be brown petrolatum jelly and its active ingredients of Zinc cloride along with ammonium cloride.
:I upped the NH4Cl content a bit with filings from my soldering stations sal ammoniac block and the resultant mix now really gets with it.
:One makes an initial clean scraping of the aluminum surface with a cheap large jewelers screwdriver....pressed in and used chisel style..... and then make immediate application of a covering of the flux and a continuous scraping action with the irons tip. Once a solid tinning has been acquired, I cleaned all the working area free of any flux with a vigorous cleaning with MEK . Then, afterwards, typical rosin based flux was used on the tinned area for its further interfacing to copper/tinned wiring. The technique works great.
:This had all come up due to the popping apart of an odd sized rocker switch used on some exotic medical diagnostic equipment. It seems that the frontal aluminum mounting plate was merely swaged to the aluminum housing of the switch proper and had popped apart. An inspection revealed the two side junctures would afford adequate area for the build up of a fillet of either epoxy or solder....I'll take solder any time that the soldering temp is permissible...thus....the following healthy repair result:
:73's de Edd

Edd 04/19/2007 13:06 
Marv Nuce 04/19/2007 13:28 
Thomas Dermody 04/20/2007 13:22 
eeprof 12/12/2011 10:06 
Frank Austin 04/26/2007 14:56 
Frank Austin 04/26/2007 15:07 
Lewis L. 12/07/2011 10:53 
Tom 12/04/2011 02:26 
Peter G. Balazsy 12/04/2011 07:37 

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