[VAC] Re: 1965 Black tank

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxxxx>]

I gave up trying to stick stuff to polyethylene about 20 years ago. My
research indicated that polyethylene was a nonpolar plastic and that no
adhesive would stick in a useful manner because it couldn't chemically
bond with that surface. There was a commercial technique that involved
either extremely obnoxious chemicals or a plasma etch to break bonds at
the surface so that there could be a chemical bond. Neither was
practical in a home workshop.

Polyethylene can be welded using hot air with techniques analogous to
welding steel with a torch. I've not developed either skill. The problem
with an older tank is that the reason it cracked was that over the
decades the plasticizes (e.g. softeners) have leached out or worked
their way out leaving it brittle which means any repair is likely to
only be temporary or the stress of heating parts of it to the melting
point will simply cause more cracks instantly on cooling.

35 years out of a piece of flexible plastic is really a phenomenal life,
no consumer plastic waste can or dishpan has lasted a third that long
without cracking and splitting.

Gerald J.