Hey Art,

As you would suspect, adding old paste to new paste is a ratio game.  If you
have a half jar of old paste and a half jar of new paste, and you mix them,
then the new mixture is better than the old paste, but not as good as new
paste.

For practical help, the rule of thumb that I prefer is that you should never
put old/used paste into a jar with new/unused paste.  When you are done with
the build, or done for the day, the used and unused paste should be kept in
separate containers.  At least in my humble opinion.

If you have solder paste on the stencil, and the amount depletes to a level
in which you need to add paste, I have no problem with mixing in new paste.
This will improve the condition of solder paste on the stencil.  Perhaps
this is what your coworker is talking about.

Steve A

> -----Original Message-----
> From: Surface Mount [SMTP:[log in to unmask]]
> Sent: Thursday,February 07,2002 1:48 PM
> To:   [log in to unmask]
> Subject:      [TN]
>
> Hello,
>
>     I work for a small PCB Manufacturing plant in Michigan. I am somewhat
> new to the buisness, and my co-workers have been giving me info about
> solder
> paste,  but there seems to be some questions about solder paste use
> We use Kester R562 solder paste. One of the things they are telling me is
>  mixing new solder paste with old solder paste will rejuvinate the old
> paste.
>  Is this true, or will it just ruin the new paste.
>
> Art Hampton
>

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