To Richard O. and Richard M.
        If you are looking for epoxy systems for cross section potting take a
look at 3M's Scotchweld line or Grace Specialty Polymers Stycast line. They both
carry products that are low viscosity(<20kcps)for good impregnation, optically
clear, two component with a fairly fast cure(1HR)and inexpensive.
        If you're trying to create a void free specimen both vacuum and pressure
cycles can be used. For this application I would use a vacuum oven.This would
allow de-airing of the potting material and the cross section coupon to achieve
a good fill. If better impregnation is required the epoxy can be heated in the
vacuum oven to lower the viscosity further. The combination of both pressure and
vacuum is normaly used on high voltage and/or densily wound transformers or
other electronic devices that can not tolerate any type of void. These systems
are typicaly expensive, large, time consuming to operate and overkill for this
application. Unless you have one of these in the back room already I'd go with
the straight vacuum oven.

        3M 612-733-2914
        Grace 617-938-8630
                                                Regards
                                                        Michael Barmuta
                                                        Staff Engineer
                                                        Fluke Electronics
                                                        Everett Wa.
                                                        425-356-6076

On Tue, 14 Oct 1997 13:40:17 -0700 [log in to unmask] wrote:

> From: [log in to unmask]> Date: Tue, 14 Oct 1997 13:40:17 -0700
> Subject: Re: [TECHNET] X-section Mounting Media
> To: [log in to unmask]
>
>      Dear Mr. MacCutcheon,
>         I am using a similar material to the one you use. My problems with
>      it are poor edge retention, and shrinkage. It also is rather viscous
>      and does not consistently fill all holes. The better choice for these
>      properties is epoxy. The problem there is the 6-8 hour cure time and
>      this is why I have not gone to that material.
>         I saw once long ago, that epoxy placed in a pressure chamber will
>      squeeze the liquid into the tightest blind cavities. The plant I saw
>      this at has been closed for years, but I remember they were buying an
>      inexpensive epoxy resin from a local company. It was on the order on
>      1/10 the cost of other systems. It was amber and glass-clear.
>         I do not remember the pressure used (this would also heat the
>      sample). I do not remember the time it took to cure. It was longer
>      than the acrylic and thus did not interest me (at that time). At this
>      time I would gladly accept double or triple the cure time (up to 1.5
>      hours) to realize the benefits of epoxy.
>         This does not exactly give you an answer, but I have been meaning
>      to ask this list about pressurizing epoxy and have taken the occasion
>      of your inquiry to do so.
>         Does anyone have any information on pressurizing epoxy to cure
>      samples?
>      Thanks
>      Rich
>
>
>
> ______________________________ Reply Separator
_________________________________
> Subject: [TECHNET] X-section Mounting Media
> Author:  "TechNet Mail Forum." <[log in to unmask]>,          Richard MacCutcheon
> <[log in to unmask]> at INTERNET
> Date:    10/14/97 1:10 PM
>
>
> We are currently using Buehler Sampl-Kwik for our coupon mounting.
> However, due to cost issues we are looking at alternative compounds.
>
> I've seen acrylics, polyesters, and epoxies.  The epoxies have very long
> cure times and have eleminated them from consideration.
>
> We grind both by hand and on a Nelson-Zimmer system.
>
> What compounds do you use and why?
>
> Are acrylics preferred over polyesters?
>
> Any information would be greatly appreciated.
>
> Thanks for your time.
>
> Richard MacCutcheon
>
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