Re: [Killietalk] WEld-on??

["Mark & Peta" <mbethke at socal_rr.com>]

Interesting, We thought the cracks we occasionally got in the assembly was
due to stress as they seemed to happen in two settings, complex curves and
cold weather.
We never annealed the material , but then the boss just yelled and we would
touch the Weld-on to the crack and MOST disappeared. I know that the
denatured alcohol is not a eco-friendly chemical but we had to use it as 20
years back all plex seemed to have release or processing oils on it . That's
before they used self adhessive or static charge to seal the plex with
urethane film. It was a bold new world at that time , the wild west of
plastics, or at least I had cuts on my hands from the crud.

Thanks again,
Mark & Peta, Max & Sam Bethke
mbethke at socal_rr.com
8450 Canby Ave.
Northridge
CA
91325 3704
U.S.A.




----- Original Message ----- 
From: "Wright Huntley" <whuntley at verizon_net>
To: "killifish discussion list" <killietalk at aka_org>
Sent: Wednesday, April 07, 2004 5:26 PM
Subject: Re: [Killietalk] WEld-on??


> >
>  > In a message dated 4/7/04 1:39:57 PM, cgraseck at optonline_net writes:
>  >
>  > << My experience is that one should never use alcohol of any sort on
>  > acrylic.  >>
>
>
> Many years ago, I had a project that needed an intricately-machined
> shape, that we made starting with cast (maybe extruded?) acrylic tubing.
>
> Overnight, the beautifully turned 2"X6" piece developed cracks all over
it.
>
> The second one did the same.
>
> I figured machining generated incipient, but invisible, cracks and that
> thermal changes overnight forced the cracks to grow. I don't remember if
> we cleaned it with alcohol, but think it was more likely that we just
> used water and a bit of detergent to remove coolant residue.
>
> I saved the third one we made by annealing it in a beaker of water. I
> set an aquarium heater to a very high value (180-190F) and slowly heated
> the piece, allowing it all night to cool in an insulated space.
>
> Never had another crack, after that, and about 8 of them operated in an
> outdoor setting for many years, as I recall.
>
> Acrylic is a very glassy material, and any initial crack takes very
> little external disturbance/force to make it propagate. It's like the
> way a glass cutter starts cracks in glass, and minor external stress
> pops them through the sheet.
>
> I agree with the suggestion to use the Weld-On to seal edges, as that
> should work better than annealing, and beats hell out of uniformly
> heating/cooling larger sheets.
>
> Wright
>
> PS. Denatured alcohol is ethanol rendered tax immune by added "stuff"
> that makes you sick. It is not a good idea around tanks (makes fish
> sick, too). Isopropanol (aka propanol-2) is very different and is the
> main one in rubbing alcohol. Cheaper versions have only isopropanol and
> water. Fancier ones have added lanolin o/e to keep from drying skin.
> Read the label, for you do not need any oils in your fry water.
> -- 
> Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net
>                      760 872-3995
>
>          Eschew obfuscation and bloviation!
>
>
>
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