[Boatanchors] Re: Superglue? (was Loc-tite)

[Barry L. Ornitz]

Jack Taylor, N7OO, asked:

> Does Superglue really work?  Over the years I've seen some
> fantastic claims made for it on TV, but I've not been able
> to duplicate them!  (Except to glue my fingers together.)

and J. Forster replied:

> 'Superglue' is very good for some purposes and close to
> useless for others. The TV stunts are done with specially
> prepared surfaces that mate extremely well and may be
> prepared with special catalysts.

Actually the original TV stunts done with Eastman 910 adhesive
used nothing more than very smooth, clean surfaces.  No
special catalysts were used.  Of course, this is the ideal
situation for these surface catalyzed adhesives.  Capillary
action between the two smooth surfaces insures a void-free
joint.  This is a key element - these adhesives work best
between two very closely fitting parts.  Porous surfaces
generally require some sort of sealer before the superglue is
applied.

> Superglue is NOT a void filler, like epoxy. It will usually
> not survive long term moisture and will attack and ruin some
> plastics, either by crazing them or causing them to turn to
> mush. It does bond skin and other tissue quite well and
> is used as a replacement for stitches in some applications.
>
> There is no universal 'best glue'. You need to match the
> glue to the problem.  Gluing steel or aluminum is very
> different than rubber or plastic or skin.

This is good advice John gives here.  Matching the glue to the
problem is extremely important.

Sheldon Daitch, WA4MZZ, suggested the following website:

> I can't vouch for the accuracy of this site, but take a look
> at:
>     http://www.thistothat.com/
> for gluing information.

I looked at this site, and while it has lots of useful and
practical information, it is far from being the best advice
for all situations.  Having spent most of my professional
career working for companies that manufactured polymers and
plastics, I can say that gluing plastics is a quite
complicated issue if you expect good results.

A good example is polyacetal (Delrin�) plastics.  They glue
well with epoxy glues _IF_ the surfaces are etched first.  And
this requires solvents and chemicals not likely to be
available to even the most determined home experimenter.
[Those nice little plastic parts in the switches and
potentiometers of Tektronix 7000 series of oscilloscope plug-
ins are mainly Delrin.  Other than these parts, almost
everything else in these modules is user repairable.]

        73,  Dr. Barry L. Ornitz     WA4VZQ     ornitz@tricon.net