- Member since
January, 2004
- From: Canada, eh?
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8,057 posts
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Posted by doctorwayne
on Monday, March 26, 2018 7:36 PM
Any adhesive which doesn't somehow react with the plastic (melt it) won't make a permanent bond. That's one very good reason why ca is not a good cement for styrene - it'll stick, but not permanently unless there's also a mechanical connection, such as interlocking mating surfaces.
If you're using MEK, or any other solvent type cement, don't necessarily use the brush-in-cap for all jobs, as sometimes, it's simply too big. I have laminated .005" styrene to .060" styrene without issue: the key is to use the proper amount of solvent cement and to let it dry to a degree where it will still make the bond, but not distort the materials. That may call for a little experimentation, but the key is to not trap still-wet solvent between the two surfaces - you can get away with it with thick styrene, but not the thin stuff, although .030" isn't all that thin. In fact, were I attempting the job which you've outlined, I'd coat the thicker piece fairly liberally with MEK, and then the thinner stuff less so. The thinner application will dry more quickly, but the solvent has already, by that time, prepped the surface, and when the heavier piece shows no more patches of liquid, you should be able to bring the two together without issue.
As for contact cement, I use it primarily where I want to join dissimilar surfaces, and if one of those surfaces is styrene, I've found that prepping it first with an application of MEK, then applying the contact cement to the other surface first, the MEK on the styrene, by that time, has mostly evapourated. However, it has affected the styrene enough that when I apply contact cement to it, it goes on much more smoothly because the solvent in the cement isn't being absorbed by the styrene, as it would if the surface hadn't received the preparatory application of MEK.
Wayne
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