MEK Substitute and current plastic cements

Andy Carlson
 

Don, I can surmise that your chemist friend has never built styrene single sheathed patterns, at least not with ACC.

Years ago Al Armitage recommended MEK for styrene fabrication for multiple reasons. Not lost on me was his mentioning MEK is 100% evaporative--that is, every bit of MEK we use will dissipate away to nothingness. You may wonder why this is important; and it is to prevent sometime reactions of residual solvent with RTV mold material. The gentleman who mentored me on mold making and casting started out with model pattern making using Testors liquid cement and many of his early molds had problems curing completely. This was prevented with the switch to MEK.

I have evolved beyond being struck with warpage years ago. Laminating 0.005" styrene plates to a thicker styrene substrate caused lots of warping. That has been solved with a glueing technique I have shared with this group a few times over the years.

Regards to everyone!
-Andy Carlson
Ojai CA

On Wednesday, August 21, 2019, 6:09:33 AM PDT, Donald B. Valentine via Groups.Io <riverman_vt@...> wrote:


    OK folks, Bill Aldrich, whom as I mentioned has a doctorate Inorgamic Chemistry, kicked this cement business
around for about 45 minutes. For small plastic parts/pieces and such Bill uses ACC for almost everything. For other
things he uses acetone and keeps it in a bottle with a cork or rubber stopper to seal it tightly and not lose it from
evaporation.......He also uses ACC when joining sheet material and notes that cements
that actually dissolve sheet material to join them cause a warpage problem that may not show up for a year or more.
This is because even if the sheets being joined are of the same material all too often each sheet with cure at a different
rate. Since there is shrinkage involved in the curing a different rate in each sheet will cause warping. Thus he uses the
ACC for sheets as well as all small parts. He did note that MEK or trichloroethylene can be used but doesn't particularly
recommend them.


Hope this information is helpful, Don Valentine

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