Deconstruction

Got a question about techniques, materials or other aspects of physically building a model? This is the place to ask.

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TER-OR
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Deconstruction

Post by TER-OR » Thu Jan 05, 2006 11:16 pm

You have a model you want to turn back into pieces.
How do you do it?

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Post by en'til Zog » Sun Jan 08, 2006 11:41 am

Aside from the usual hammers, chisels, rubber mallets, and the ol' Makita Sawzall?

A lot of older tube type glues turn fragile with age. It's often hard to STOP models built with them from coming apart. To encourage the parts to separate you can stuff the model in the freeze of your refirgerator and let the cold weaken the joints. You could get technicians "Freeze Mist" used for supercooling electronic components to test for thermal problems, and spray that extremely cold stuff on the joints - but be REAL careful 'cause that stuff can cause cold burns. You should be able to get it at an electronics supply house, or maybe ALL or Jameco electronics.

Try running your thumbnail between the parts. IF the glue is old or intermittant, you can often pry the parts apart this way, but with some risk of distortion.

Superglues tend to have great strength in one direction (pulling straight apart), but not in others. They usually aren't too good for shear loads. You could try the freezer trick first, then sliding the parts apart.

Or just let the model age and it may fall apart all by itself. May take a few years.... :evil:

If you or the builder used a fusion cement like Tenax-7R which actually fuses the plastic parts into one unit - they ain't comin' apart without using a cutting tool. Sorry. :cry:

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Post by Kylwell » Sun Jan 08, 2006 11:53 am

I've found a good sharp exacto and some gentle prying works most of the time. Hadn't though of using a cold spray (can of compressed air turned upside down).
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Post by Jonas Calhoun » Sun Jan 08, 2006 12:36 pm

I've also used a razor saw. Make sure you cut somewhere that doesn't have a lot of detail (doesn't have to be the original seam), and then you can put a piece of styrene in there as a shim. Get the styrene shim the same width as your saw kerf. The advantage is now you have a lot of surface area to glue with. I did this on one of the Valkyrie weapons that I glued one half backwards (the missle pod, I believe).

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Post by Darth Humorous » Mon Feb 20, 2006 1:16 am

If the model was glued with old type tube glue and sometimes the water-thin styrene cements, I have found paint thinner (mineral spirits) is about the only chemical way to weaken the joints enough to get them apart.

HOWEVER, it must be watched like a hawk. The technigue I use is to liberally dribble the paint thinner over a joint I wish to separate, confining it to the seam as much as practical. I do this over a large enough shallow pan. Something like a medicine dropper or turkey baster can be used to suction the thinner from the pan, and then squeezed out on the seam from above, dripping back into the pan. Sometimes a brush can be used, but the flushing volume is not as much, so it might not be as effective except for very small joints.

Occasionally, and with utmost gentleness, pull, flex, pry or whatever is best suited to the seam in question. If the seam is inclined to come apart, the originally glued surfaces will have a gritty appearance as it comes apart. Once it comes apart, IMMEDIATELY dunk the pieces only into a bucket of soapy water and swish around. This halts the action of the mineral spirits, which is much desired, as explained below.

I limit the procedure to 10 minutes because after that, the plastic tends to become soft and weak. If the joint doesn't come apart in that amount of time, I have to decide if I want to make an attempt later after the plastic has firmed up again, or try a more destructive method. Whatever I decide, the wait for the plastic to firm up may take a few days. The deeper into the 10 minute period you work before the joint lets go, the longer the wait for the plastic to firm up. If I'm lucky, the joint will come apart within a minute, and virtually no softening has occurred. Even in such cases, I still wait a respectable amount of time before I do anything else with the pieces.

A note. If prying with a tool is the best or most expedient method, as it often is, there most likely will be some gouges, mars or scars. It depends on the tool used, what the tool is made of, the method of prying, how long I've been at it, etc. as to how much damage occurs. In all cases I have encountered and succeeded in separation using this technique, the surface restoration is not insurmountable, and leaves the parts able to be assembled in their original manner. Of course I can see where some models with very fine and complex detail right at the seam may demand a different separation technique, but no matter what method is used, surface restoration is necessary for any parts with such a seam.

Another note. For the sake of minimizing aggravation by the smell, I recommend the so-called "oderless" or "low odor" types of paint thinners.

A final note. It took longer to write this and may take you longer to read and digest this than it does to actually do it.

Hope this helps.

Mark

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Post by jardann » Fri Jun 23, 2006 3:00 pm

I have used a product called Greased-Lightning. Actually used it to strip paint off of old models and it does that pretty well. It also seems to weaken the glued joints without causing problems to the rest of the kit plastic. I soak the model in it for up to a day, but usually it only takes an hour or two. Be careful, and check back often, because I would think that the longer the plastic stays submerged, the more likely it will be to become brittle. Then as I'm removing the paint, I gently flex the glued areas and most parts come apart fairly easily with little distortion or breakage. Not sure how this affects CA glued joints.

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Post by Spacephrawg » Wed Jul 05, 2006 8:04 pm

Could y'all expound upon the way these methods weaken the plastic? I've noticed that paint thinner/mineral spirits perminantly fogs up any clear plastic. Is that part of the begining of it's attacking the plastic chemically? Also, once its started to weaken the plastic, is the effect perminant or does it go away after its dried up? Will the plastic be perminantly weakend and crapulent after the process?

About the general topic, I was under the impression that styrene plastic glue, i.e. "model glue" ala Testors, was something that simply fused the plastic surfaces together. I did not know that it could be disolved. I thouhgt it became one with the plastic or some odd weirdness like that. How does it really work? ::much confusion over here::

What ever happend to just prying things appart? I've had good luck with that on some models. THe paint stripping will be interesting tho. Btw, is there any paint stripper that wont attack the plastic?
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Post by Darth Humorous » Thu Jul 06, 2006 11:55 pm

Spacephrawg wrote:Could y'all expound upon the way these methods weaken the plastic?…Will the plastic be perminantly weakend and crapulent after the process?
In the use of mineral spirits, the plastic surface becomes brittle right at the glued joint, and looks like it is crystalizing(?) and slightly swelling. As a result, the joint area becomes rough, and eventually crumbly. This crumblyness is permanent, and you would want to remove it anyway. After all, once it becomes crumbly, those miniscule chunks have already separated from the main body of the plastic. The thing to watch for is the severity of crumblyness before the joint wants to yield. This is why technique and timing is so critical. Once the process is arrested and the part cleaned up (after successful separation), the formerly glued edge will take on a pitted appearance. I can't speak too much to the strength immediately following arresting because I always wait several days after before I attempt to do any regluing, and by then it seems normal. Putty will fill the pits. Any concerns about weakened joints can be dealt with with thin styrene strips bridging the seam from th inside or gap filling super glue. I've never done either one, and have had no failures.
Spacephrawg wrote:About the general topic, I was under the impression that styrene plastic glue, i.e. "model glue" ala Testors, was something that simply fused the plastic surfaces together. I did not know that it could be disolved. I thouhgt it became one with the plastic or some odd weirdness like that. How does it really work? ::much confusion over here::
Well, if ya think about it, such glues DO fuse the plastic by FIRST dissolving the edges. So in effect, there are these two edges in contact with one another that are turned into a semi-liquid state. In this state, the molecules have an affinity to bond to one another. Eventually, when the active ingredients are spent in chemical reaction and evaporate, and the joint soildifies (slowly over time).

This is the sort of thing that happens during metal welding. In that case, two pieces of metal placed into contact (or near contact) and the edges are heated to a semi-liquid state, at which point the molecules have an affinity for one another and bond. Of course, adding metal via a filler rod is often necessary, but not always. Once the joint has cooled, the the weld is complete.
Spacephrawg wrote:What ever happend to just prying things appart? I've had good luck with that on some models.
And if your luck holds out, more power to ya. It is certainly worth a try to the point ya think yer gonna break it. Then ya better stop.

Spacephrawg wrote:THe paint stripping will be interesting tho. Btw, is there any paint stripper that wont attack the plastic?
In varouus posts, I've commented on the righteousness of Castrol Super Cleaner. Bio degradable and water soluable, it WILL dissolve your skin, which is why rubber gloves are a must. More ito the point, tho, it WILL remove paint and NOT touch the plastic. Great stuff, IMHO.

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Post by bluesman » Fri Sep 08, 2006 7:46 am

depending on the parts, I have wedged a metal ruler between the seams and flexed it to pry the parts loose. Go slow and work a small section at a time
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Post by Saturn » Fri Sep 08, 2006 11:14 am

I deconstructed an old DS9 Runabout by throwing it in the freezer. I had originally assembled it with Testors tube glue, and freezing makes those bonds extremely brittle. After a day or two, it was a simple matter of twisting and popping the parts off.

I don't know if models assembled with liquid cement (MEK) can be disassembled without major damage, since those joints are literally welded together.
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Post by jimboh1 » Mon Jul 23, 2007 3:21 pm

Will Coke help disolve old Testor glues, I wonder? I have an old kit to strip and deconstruct; perhaps I can kill two birds with one stone...
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Post by Kolschey » Mon Jul 23, 2007 4:00 pm

I've actually used boiling water effectively to soften the glue joints of various toys that I've needed to disassemble.

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Post by Butters » Tue Jul 24, 2007 11:52 pm

Does acetone react with styrene? I need to remove some metal that's been super glue to styrene.
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Post by Mr. Badwrench » Wed Jul 25, 2007 2:26 am

I think it will be ok, but I'm not sure. Put some acetone in a jar or an old Spam can, (I know you got some), and drop in some sprue. Check to see it it's gone in the morning. Or I can go out to the garage and try it, and sell you the information later. :P
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Post by Butters » Wed Jul 25, 2007 9:19 am

Exactly what I did. Got some sprue from the same kit as the parts (so the plastic'd be exactly the same) put it in a jar with Acetone, for an hour and checked. No reactivity at all after an hour.

Thanks.
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Boiling Water?

Post by Scratchawan Learner » Sat May 31, 2008 9:35 pm

Tried boiling water once upon a time.... I had a P-47 Thunderbolt, with a warped wing. I'd heard someone mention placing styrene in Boiling water... Big mistake. HUGE. Boiling water is WAY too hot for styrene, and wound up distorting my plastic beyond all hope of use... had to buy another kit. (which was what I was trying to avoid to begin with).
I advise using a number eleven exacto blade... that has been heated.
I have used this method in several instances, to coax recalcitrant parts apart.... both those that had been secured with tube glue AND parts that have been secured with Tenax, or Ambroid. I should mention... that the liquid glue joints were a LOT stronger. I hate tube glue with a passion, and never do use it. ProWeld and Tenax are a lot easier to control, and god knows the joints set a lot faster, and cleaner. I only use a razor saw to cut joints, if the joint is too thick to use with the hot knife method.
Rarely have a found a joint that a hot knife didn't work well on... but they do exist. Acetone didn't work on Styrene plastic as a solvent? That's rather odd, as Testor's cement names it as an ingredient. You might try Xylene, or Methyl Ethyl Ketone...but only if A. your desperate, and B. if you work outside.... M.E.K. is a very viciously dangerous substance, with a very long and distinguished Material Safety Data Sheet... use at your own risk, which will be considerable. M.E.K. is used in the laminate industry, as the solvent of choice, to remove contact adhesives with.
Work with a respirator folks... and save your health.

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Post by AbsoluteSciFi » Tue May 31, 2011 9:27 pm

Normally, I use a Dremel Tool to get things apart, but most of my "kits" are never put together, so there is no problem there...
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Post by seam-filler » Wed Jun 01, 2011 2:44 am

Butters wrote:Does acetone react with styrene? I need to remove some metal that's been super glue to styrene.
Yup - big time. In fact it's what I used to use to dissolve excess sprue to make a gooey filler. Furthermore, the pplastic is permanently soft after it is attacked by acetone.
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Post by Tankmodeler » Wed Jun 01, 2011 7:46 pm

Yeah, for ghod's sake, don't use any of the agressive or "hot" solvents on styrene. You'll end up with nothing but a mess of melted styrene plus a bunch of dead brain cells.

Styrene parts, properly bonded, are generally a pain to get apart. Expect to use force and expect for some seams to just not open up. Parts bonded with CA glue can be relatively easily pried apart, expecially after freezing, but if you've used normal styrene glues, then the pard really are fused together. If the bond line has a relatively large area, you can expect to have to cut it or break it apart, with varying results...

:)

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Post by DeltaVee » Sat Oct 29, 2011 1:28 pm

What is the "brittle" area at the joint you all are referring to? Is it excess dried tube glue, or is it the fused join line? If the later, then when you sand that part down to create 2 new mating surfaces, you've just made the cross-section smaller.

I guess on small fiddly bits like joy sticks you're taking a huge gamble?

BTW, this was exactly the thread and even the exact title I was looking for when I logged in. Kudos - again - to SSM and patrons, thereof.

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Post by DeltaVee » Sun May 17, 2015 1:23 pm

Well, I'm back at it, trying to take a vintage model back to its pieces. Do I recall something like brake fluid or transmission fluid working?

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Post by Lt. Z0mBe » Sun May 17, 2015 11:34 pm

DeltaVee wrote:Well, I'm back at it, trying to take a vintage model back to its pieces. Do I recall something like brake fluid or transmission fluid working?
Super Clean, oven cleaner, and brake fluid are the ones I have tried. Beware, though that Super Clean will soften any putties used on the build. Oven cleaner and brake fluid will dissolve the lacquer based putties.

The Super Clean - just add about it to water at, I don't know, 1-to-5 ratio and soak the piece. You can go 100-percent but it's overkill. With the brake fluid, just submerge the piece in it. With oven cleaner, cover the piece in the foam, taking care not to breathe it because it will melt your lungs (no exaggeration) and put it in a garbage bag to sit for a few days.

In all cases, wear gloves and scrub the model afterwards with a toothbrush and dish soap. I cannot emphasize enough the gloves, as those chemicals will strip the oil right of your skin and your hands will just crack open.

I hope this helps.

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