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Author Topic: Removing Sigment Glue  (Read 797 times)

Online Dave Hull

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Removing Sigment Glue
« on: January 09, 2019, 10:01:22 PM »
Is there a solvent that will remove Sigment glue?  I tried multiple searches and did not find anything....

I am guessing that it is Sigment because it is clear and shiny, and smeared in quite a few places. It is very hard, and has that sound when you try to cut it or sand it.

Meantime, I have started soaking the joint with acetone and lacquer thinner. These did not immediately attack it...but maybe it will soften it up with some time. I'd rather not mess with methylene chloride strippers.

The project is a gifted OPP  (Other People's Plane) that has a surprising amount of negative incidence in the horizontal stabilizer among other issues. The plane was structurally nearly complete (maybe 75% or so) and it looks like the builder gave up on it. Some things show decent workmanship and others not so much. And it has a few building techniques that I haven't/wouldn't use but a couple that are kind of neat.

If I can get the stabilizer off, then the fuselage is worth reworking. If I have to build a new stab and elevators that wouldn't be too bad, since it really could use a better joiner system. (It is already hinged.)  If taking all the quirks out causes too much damage, then the whole deal should have gone into the fireplace at the outset....

I already dealt with severely canted engine bearers which had nice little aluminum pads inset--at the same angle. And egged out bolt holes that lean forward. And so on....

When I started modeling somewhere around 5 or 6 years old, all I got was white glue. Later, when I got older, I was allowed to use Ambroid, but didn't like it better than the Titebond that I had already upgraded to. So I find myself not knowing the answer to a typical rebuilding question...that others may consider common knowledge.

Thanks, guys

Divot McSlow

Offline Ty Marcucci

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Re: Removing Sigment Glue
« Reply #1 on: January 09, 2019, 10:04:24 PM »
Acetone.  It will take time, but if you can cover it with an acetone soaked rag, it may go faster.
Ty Marcucci

Online Dave Hull

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Re: Removing Sigment Glue
« Reply #2 on: January 09, 2019, 10:25:01 PM »
Thanks, Ty.

Ok, I'll keep after it with acetone. Maybe I can find a cotton or Dacron string to lay in the corner between the fuse and stab and soak that.

Will let you know how it goes....

Divot McSlow

PS--I was just contemplating cutting away the balsa fuse sides and splicing in new rails for the stab to sit on. Probably would be quicker. I'd lose a little strength due to the butt splice at the bulkhead (LE of stab) but it'd probably be just fine.

Offline Akihiro Danjo

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Re: Removing Sigment Glue
« Reply #3 on: January 10, 2019, 03:06:04 AM »
Ty san is correct, use acetone.
For that purpose, I apply acetone using a small brush and brush the glue to soften it. Repeat this procedure several times till dissolving.

Aki

Online Brett Buck

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Re: Removing Sigment Glue
« Reply #4 on: January 10, 2019, 10:06:44 AM »
Almost anything in the acetone or lacquer thinner area will work. I prefer lacquer or dope thinner, just because it doesn't evaporate as quickly, so it has a chance to penetrate before its gone. In any case, you can use a paper towel and soak it, then press it up against the offending joint. It won't hurt balsa wood,  so you don't have to be very careful unless it is finished.

    Brett

Offline Tim Wescott

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Re: Removing Sigment Glue
« Reply #5 on: January 10, 2019, 02:52:14 PM »
Indoor freeflight nutcases experts use Duco cement (basically Sigment) mixed with acetone for trim adjustments -- the stab (and sometimes wing) is glued on with a tiny (light!) dot of glue; to adjust you put on a teeny drop of the thinned stuff, which softens what's there and lets you move things, then dries in time for you to put in another competition flight.

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Online Dave Hull

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Re: Removing Sigment Glue
« Reply #6 on: January 10, 2019, 05:37:56 PM »
After a couple of hours with the acetone and with the glue still crispy hard--I got impatient and went caveman on the job. I 'zactoed the fuselage sides right below the horizontal stabilizer and away it came. This plane was only partly constructed, so nothing else was in the way. Then I jigged up the fuse off of the now-straight engine bearers (no top nose block in the way yet) and fed the HS mounting surface into the vertical belt sander. Hey, presto--done. Will add back a bit of material using some balsa strip to get the stab height where it belongs. Now working on making a new HS and elevators to fix some other issues.

Not a candidate for the fireplace--yet!

It's great to be able to hear options from youse guys. Thanks!

Divot McSlow

PS--The next issue is likely to be the nose block(s). They are partially carved on the outside, and past the point where the recommended 1-3/4" diameter spinner will blend in. So I either need to be looking for a 1-1/2" spinner, or choppin' and splicin' some more of Equador's finest....  Stay tuned.

Offline Tim Wescott

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Re: Removing Sigment Glue
« Reply #7 on: January 10, 2019, 05:57:28 PM »
If it's still crispy-hard and hasn't even gotten a bit gooey on the surface, then it's not Sigment.  Acetone on Sigment should act about the same as water on hard candy.

So it was probably epoxy, and you did the right thing.
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Offline FLOYD CARTER

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Re: Removing Sigment Glue
« Reply #8 on: January 11, 2019, 12:50:18 PM »
Instead of trying to remove the glue, you can remove parts by cutting away the balsa next to the glue joint, leaving the original glue intact.  Balsa is easier to shape than a glue joint.  Glue the part back after shaving or sanding the balsa to re-position the part in question.
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Offline Steve Helmick

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Re: Removing Sigment Glue
« Reply #9 on: January 11, 2019, 03:20:42 PM »
When trying to soften dope or acetate based glue joints, try soaking the wood adjacent to the glue, to get underneath the glue.  If you lay some paper towels (strips?) on the glue, cover with Handywrap  to keep it from evaporating so fast. Or, go Caveman. A well designed (and good fitting) splice can be as strong as the original joint.  #^ Steve
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Online Brett Buck

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Re: Removing Sigment Glue
« Reply #10 on: January 11, 2019, 06:30:28 PM »
After a couple of hours with the acetone and with the glue still crispy hard--I got impatient and went caveman on the job. I 'zactoed the fuselage sides right below the horizontal stabilizer and away it came.

    If it did not respond to acetone, it's not SIG-MENT. Since we discussed it the other day, I glued random stuff togther with it, and acetone or lacquer thinner went right through it. I might be able to believe that its more difficult with age, but its just plastic dissolved in acetone or MEK, no matter how long it has been.

     Brett

Online Dave Hull

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Re: Removing Sigment Glue
« Reply #11 on: January 12, 2019, 03:11:56 AM »
I'm curious too, so I will look at it again tomorrow. (It is pouring rain right now, and supposed to keep coming down---so no flying for a few days. Everyone knows it doesn't rain in California--except on the weekend.)

The stuff was clear, and "crispy hard" like I have seen Ambroid and Sigment get when I used them before. When I was cleaning up globs of glue in a corner, I hit it with Tim's favorite tool---the Dremel "death wheel" to get a square corner back between the engine bearers and the bulkhead. That caused a noticeable smell, so I want to go hit a scrap and see if I can tell what it is. I was kind of focused on the job before, not the autopsy....

Soaking the joint and inevitably the balsa on both sides of it did not begin to soften it up. So I understand everyone's input that either the acetone was evaporating too fast, or it isn't a cellulose glue.

Today I built a completely new stab and elevator set with a decent wire joiner instead of a wood stick with a scrap of carbon on it. So I'm good to go. The incidence is gone, and the fuselage joint surfaces cleaned up great. Going back together will be no problem. (If you are going to work on an OPP, it is MUCH nicer when it is not already painted, and even better that it has zero oil soaking.)

My guess is that this was built (actually, partially built) about 12 years ago. Whatever kind of glue it is, has had a lot of time to get hard.

The whole glue thing is interesting when you are doing rebuilds of OPPs. Not to mention the strange stuff I've seen on ARFs. Some of it looks like UV-cured glop, which sure would speed thing up....

Divot McSlow

PS--Now the plywood bellcrank is a whole 'nuther story....


Online Brett Buck

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Re: Removing Sigment Glue
« Reply #12 on: January 12, 2019, 12:04:47 PM »
The whole glue thing is interesting when you are doing rebuilds of OPPs. Not to mention the strange stuff I've seen on ARFs. Some of it looks like UV-cured glop, which sure would speed thing up....

     That's probably about as good as cyanoacrylate  - as near as I can tell, in either product the end result is that the adhesive is some form of acrylic plastic, one cured via only chemicals, the other chemical triggered by UV. Either leaves a rock-hard and rather brittle more-or-less clear plastic behind.  I don't know what happens do it where the UV cannot reach. That stuff apparently has a similar problem as Hot Stuff, it tends to "go off" before you use it. 

Quote
PS--Now the plywood bellcrank is a whole 'nuther story....

    I can easily imagine plywood bellcrank designs that would be perfectly acceptable, for almost any size airplane. It would not be my first choice for large airplanes, but aircraft plywood is pretty darn tough stuff, and wood is generally much less prone to fatigue than almost anything else - the glue is another story, of course.

     Brett

Online Howard Rush

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Re: Removing Sigment Glue
« Reply #13 on: January 12, 2019, 12:15:43 PM »
Nitromethane will dissolve CA, as I learned with a free flight engine timer.
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Online Dave Hull

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Re: Removing Sigment Glue
« Reply #14 on: January 12, 2019, 02:35:10 PM »
The bellcrank was buried in the fully framed wing, and I was going to inspect it or I wasn't going to fly it. I could just barely see a tip thru the rib holes at full travel. This is a plane that has light-ply fuse doublers, so....

The bellcrank itself was rough looking, but actually pretty serviceable. Made from 5-ply 1/8" birch. It had some hand hammered brass tubing bushes for the cable leadouts that would work just fine. And a copper tubing bush thru the mounting hole. What was not so good was that it was held in via a machine screw that could not be tightened down--because there was no "axle bushing." In other words, tightening down the nut pinched the bellcrank against the spacer washers. The screw was not separately fixed to the platform. (This plane will probably have a 15+ lb pull on it during flight.)  So it would have wallowed out or bound up in short order. In rebuilding OPPs, I find that control installations seem to baffle or frustrate builders. Either they don't know a standard way to do it, or think that good enough is good enough, or that somehow they will "get away with it."  Of course, if you work on OPPs abandoned projects, there is going to be a reason for that....

I've got an old Veco metal 'crank being fitted up right now. I need to check the leadout guide locations to see if they going to be ok, or if I'm going to have to move the eyelets and open up the holes in the ribs....

Here's a taste of a more modern project. A bellcrank for a future big 'un.

Divot McSlow



Offline Tim Wescott

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Re: Removing Sigment Glue
« Reply #15 on: January 12, 2019, 03:24:49 PM »
     That's probably about as good as cyanoacrylate  - as near as I can tell, in either product the end result is that the adhesive is some form of acrylic plastic, one cured via only chemicals, the other chemical triggered by UV. Either leaves a rock-hard and rather brittle more-or-less clear plastic behind.  I don't know what happens do it where the UV cannot reach. That stuff apparently has a similar problem as Hot Stuff, it tends to "go off" before you use it.

There's a two-part acrylic glue out there too, for industrial use.  I couldn't start to tell you what it is, but it comes as a double-cylinder thingie that you dispense with a tool that looks like a caulking gun, through a disposable mixing tube.  For the guy applying it, you just put a fresh mixing tube on it, squeeze the trigger, and get glue.
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Online Dan McEntee

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Re: Removing Sigment Glue
« Reply #16 on: January 12, 2019, 04:23:32 PM »
There's a two-part acrylic glue out there too, for industrial use.  I couldn't start to tell you what it is, but it comes as a double-cylinder thingie that you dispense with a tool that looks like a caulking gun, through a disposable mixing tube.  For the guy applying it, you just put a fresh mixing tube on it, squeeze the trigger, and get glue.


   Adds for that stuff pop up here on the list. I just watched a video of it being applied while I watched the video about the jet pack. Weld-It or something like that. The pop up adds change often but don't see one for it right know.
  Type at you later,
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Online Dave Hull

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Re: Removing Sigment Glue
« Reply #17 on: January 13, 2019, 05:37:24 PM »
Ok, here's the results of a 14 hour soak.  I put the stab/elevator assembly into a large Ziploc bag. I placed a folded paper towel soaked with lacquer thinner on top of the remaining fuselage strips that were still stuck to it after the 'zacto incident. On the outside of the closed bag, I pressed a folded shop towel over the area, and weighted it down. And left it to do whatever it was going to do.

After about 14 hours, I took it out of the chemical stewpot, and could pull away the fuse pieces. Then I scraped away the now gummy glue. The thinner also migrated to the tips, which came off the stab.

Conclusion:  it was likely Sig-Ment or a similar nitrocellulose adhesive. It just took a lot more serious soak (wetter and longer) for it to soften the well cured glue.


Dave

PS--I hear guys say all the time that straight nitro will remove CyA. It totally depends on the joint geometry and materials. If there is full exposure to the face of the glue joint, then probably so. If the CyA has wicked between aluminum and plywood, or some similar combination--well good luck. I soaked--it was literally submerged--a F2C repair job for two weeks and was unsuccessful. If all that is exposed to the solvent is the edge of the bondline, the propagation rate will mean the joint will likely come apart in the next century. Don't wait up.

PPS--And while I waited for the glue experiment and listened to the Rams game--I finished up a canopy plug for the "Sig-Ment Specical."  Looks pretty good. Now I gotta go drink 2 liters of soda....

Online Howard Rush

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Re: Removing Sigment Glue
« Reply #18 on: January 13, 2019, 08:14:53 PM »
Nitro will release fingers glued to a wood table with CA. It took awhile, but most of the time was spent waking my wife, who was sleeping in the bedroom above the shop.
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Online Dave Hull

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Re: Removing Sigment Glue
« Reply #19 on: January 13, 2019, 08:19:06 PM »
It's good to know it worked, Howard. Does that mean I either need to get rid of my bench--or find a wife?

Divot


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