MEK-dissolved styrene filler?

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MillenniumFalsehood
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MEK-dissolved styrene filler?

Post by MillenniumFalsehood » Fri Feb 10, 2017 6:56 am

So I am going to be building the SFSM Survey class vessel, and I was wondering how good or bad an idea it would be to chop up some of the scrap plastic left over from cutting out the parts, dissolving it in some MEK, then putting it in the oversized panel lines all over the model?
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Post by kenlilly106 » Fri Feb 10, 2017 7:06 am

I have not tried it myself but have read that it doesn't work as it seems.

Takes a long time for the solvent to come out of it, so it stays soft for months, ad it seems to affect the texture of the filler plastic so it's not the same as the original material, making it hard to get a good surface finish.

Ken

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Post by MillenniumFalsehood » Fri Feb 10, 2017 8:11 am

Hmm... okay. What about dissolving it in something like Tamiya Thin or other solvent-based glue?
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Post by kenlilly106 » Fri Feb 10, 2017 12:08 pm

Everything I've read seems to indicate that any solvent will have the same problems as MEK.

Have you thought about Aves or something similar?

Ken

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Post by SpaceRanger1 » Fri Feb 10, 2017 1:52 pm

It actually works quite well. It dries faster when MEK is used instead of liquid cement, because the commercially available liquid cements have additives which slow the drying time.

This "plastic plastic" was proposed back in the "dark ages" of plastic modeling long before any of the proprietary modeling fillers that we use today were developed. The only similar products available at the time were wood fillers, which were not fine-grained enough for use on plastic models (with the possible exception of Duratite Surfacing Putty). Its advantages are: (1) it can be made from items already on hand, i.e., scrap plastic from sprues and liquid cement, (2) it can be mixed to any desired consistency, (3) when thoroughly dry, it has the same workability with files, sandpaper, and scribers as the kit plastic because it IS plastic, (4) it adheres to the kit plastic better than some epoxy fillers thanks to the cement, and (5) when painted it has the same appearance as the kit plastic. The only disadvantages that I have found using it are (1) it needs to be built up in very thin layers, and (2) it takes a longer time to thoroughly set than most modeling filler putties, but this depends on the viscosity of the mix and how thickly it is applied.

I've used it in the past and still have a bottle of it mixed up. I sometimes use a thin layer of it as a final application over other types of putty before spraying primer.

When making up a batch, use the back of an X-acto blade to make fine shavings off the sprue. You can even use extra coarse sandpaper to generate styrene powder. Either way, shavings and/or powder dissolve faster and better than chunks of sprue or pieces of sheet styrene. Also, the harder the styrene is to start with, the harder your filler will be. Sheet styrene shavings and powder usually make a very soft filler

Try it. I think you'll like it. It's not really suitable for filling large gaps, but it is extremely useful.
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Post by Go Flight » Fri Feb 10, 2017 9:07 pm

Flory's Models has a You Tube video on it. It works terrific. But they say for whatever reason that cutting up Sheet styrene makes a "better" filler than just chopping up sprue.

https://youtu.be/E9cAH7cVwm4

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Post by Kylwell » Sat Feb 11, 2017 12:12 am

I've done it with Tenax 7r and Tamiya Thin. Works great. MEK is troublesome stuff and getting the solvent to plastic ratio right could be iffy. Toluene might be a better substitute.

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Post by USSARCADIA » Sat Feb 11, 2017 10:17 am

I tried it as an experiment years ago. MEK is nasty stuff and won't touch it again. It took a while for it to make a goop, but then used it to make my Kestrel master. In my opinion it wasn't worth the time and effort. Epoxy putty would have been less sloppy and less toxic. I even developed some cracks where there shouldn't have been any, like it was almost too brittle. I recovered but it would've been quicker using something else.
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Post by SpaceRanger1 » Sat Feb 11, 2017 2:04 pm

USSARCADIA wrote:I tried it as an experiment years ago. MEK is nasty stuff and won't touch it again. It took a while for it to make a goop, but then used it to make my Kestrel master. In my opinion it wasn't worth the time and effort. Epoxy putty would have been less sloppy and less toxic. I even developed some cracks where there shouldn't have been any, like it was almost too brittle. I recovered but it would've been quicker using something else.
MEK is nasty stuff, but it's the basis for a lot of the liquid cements we use. And "plastic plastic" is not good for creating large objects; it's far better used as a seam filler. It's just another tool in the toolbox.
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Post by Kylwell » Sat Feb 11, 2017 2:44 pm

Part of the reason I like Tenax 7r is that it's MEK free.
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Post by MillenniumFalsehood » Tue Feb 14, 2017 8:43 pm

Thanks for all the input, guys. The reason I would rather use MEK than solvent-based welders is that it's cheaper. I can get a big can of it at Walmart for $4 vs. the $5 it costs to get a bottle of Ambroid or something. If drying time is really the only big disadvantage, then I think that will be fine for me, as I'm not concerned with slapping a kit together and calling it good.
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Post by Andrew Gorman » Tue Feb 14, 2017 9:37 pm

It does take a long time to dry, and stinks to high heaven. If you really want to cheap out, PVC primer makes a pretty good if stinky styrene cement/solvent. and it doesn't have to be purple- it comes in clear too.

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Post by hossfly72 » Sun Feb 26, 2017 9:55 pm

I used Tenax with chunks of styrene dissolved in it years ago. It does work well, but one thing I found was that it works best if you use the dissolved sprue from the kit you're building as the filler. Sprues from different kits sometimes are made from a slightly different styrene recipe and might not dissolve as well or might dissolve too well. Airfix plastic as opposed to Hasegawa plastic vs Monogram plastic... all just slightly different.

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