Why do i need to 'Flash'?

Why do i need to 'Flash'?
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Why do i need to 'Flash'? - 7/18/2003 9:56:57 AM

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But it IS a serious question

I read somewhere that i should 'flash' the Coroplast before gluing.

Err... why?

Cheers...

Goose

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Why do i need to 'Flash'? - 7/18/2003 10:06:23 AM

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It burns off the manufacturing oils present in coro, which in turn makes the glue stick better.

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Why do i need to 'Flash'? - 7/18/2003 10:25:03 AM

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Nope, there is a thread here somewhere in which a chemical engineer, who was involved in the manufacturing process for this type of plastic, sets the record straight about this. It seems that flasing, if done correctly, chemically changes the surface layer of plastic molecules and gives the glue some points on which to bond. There are no "manufacturing oils" present in sheets of coro.

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Why do i need to 'Flash'? - 7/18/2003 12:44:50 PM

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Yes, and chemical engineers, nor any engineers, for that matter, never ever disagree with eachother, and they're never wrong. I read this post, and was impressed. BUT, I have read many credentialed lengthy impressive disertations in the past on many subjects in many forums, and often times someone with similar credentials comes along and disagrees vehemenantly. Maybe he's right (his post was convincing), or maybe it's a combination of things, maybe there is some residue left on the surface of SOME SORT that the torch burns off. Who cares. The fact is the torch does something that allows the glue to adhere better, so flame. BTW, how come scrubbing the surface with abrasice pads and mineral spirits also works to improve glue bonds on coro, as well as flaming does? I doubt that the mineral spirits or the pads would effect these plastic molecules in the same way as fire. Anyhow, the technical reasons aren't important to me, the result is.

BTW, I find it annoying when someone dismisses something I say with a flippant "Nope". Even if you thught I was full of it, there is such a thing as dissagreeing politely.

< Message edited by FrankC29 -- Jul 18 2003 8:29AM >

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Why do i need to 'Flash'? - 7/18/2003 1:26:53 PM

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From: RustenburgNorth West, SOUTH AFRICA
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I have to go with Frank here,

you could for one flash the coro or wipe it with mineral spirits and ca sticks to the coro, if you don't do either you have a wing pop open soon, so there must be something on the coro that if I wipe is off/burn it off, ( maybe I am changing the surface ) it glues together..

There are people that cant seem to get to surface change/oil removed and are using zip ties to keep the TE together.

So as Frank said I don't really care what the flashing does to the coro, but IT IS REALLY NEEDED..

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Why do i need to 'Flash'? - 7/18/2003 9:17:00 PM

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It seems to me, that the coroplast has virtually no open molecules on it's surface. Which is why vinyl sticks to it so well. Flashing creates open pockets on the surface, scotch brite scratches the surface providing 'tooth' for the glue to adhere to.

The only method I will EVER use is woodpecker and poly glue. So strong, drying takes less than 4 hours in the summertime. No surface prep, other than woodpeckering. Cheaper than CA, excellent gap filling properties. I could go on and on.

Oh, and that 'oil' you 'feel' when touching coro? That's the coro repelling your own skin oil. That's why it's a good idea to clean the coro with iso alcohol or windex before you apply vinyl trim schemes or paint.

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Why do i need to 'Flash'? - 7/19/2003 12:15:55 AM

*Crash*Johnson*

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[QUOTE]Originally posted by Deadeye
The only method I will EVER use is woodpecker and poly glue. [/QUOTE]

What glue do you use?

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Why do i need to 'Flash'? - 7/19/2003 1:51:16 AM

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Elmer's ProBond Polyurethane glue. Spritz with water to 'kick' it, the more water you spray, the more it will expand.

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Why do i need to 'Flash'? - 7/19/2003 3:44:24 AM

Woodsy

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original Q "I read somewhere that i should 'flash' the Coroplast before gluing.

Err... why?"

easy, so the glue sticks, but you dont HAVE to flash, you can also sand and wipe with solvent, rub with scotch pad and solvent, wipe with solvent 3 or 4 times, wood pecker and PU, woodpecker and epoxy and may be a few i've missed

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Why do i need to 'Flash'? - 7/19/2003 4:47:47 PM

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Thanks all... makes sense.

Cheers

Goose

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Why do i need to 'Flash'? - 7/19/2003 10:34:36 PM

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Personally Ild skip the whole flashing thing ..Grab a tube of either Wall Mart ..Welder Glue or 3m Super Weather Strip Adhesive .. Just lay a small bead down press the parts together then pull them back apart .. Give them a few minutes apart then press them back together ..DONE DEAL !!! I use a combination of both ..I use the Welder glue on your spar ..I let that set up maybe 1/2 hour before i fold the top over . Then use the 3M for the rest ..You can have a wing Air Ready in less than an hour .. Just an Idea !!!

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Why do i need to 'Flash'? - 7/21/2003 1:51:37 AM

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Bobo...

Cool! Thanks for that, however way down here in New Zealand, the products that you guys enjoy are damn near impossible to find. I spent a little time on the weekend on my P-51 project, and tested CA, an ADOS product and my hot glue gun. The hot glue was the only one that im happy using, but unfortunately I wont be enjoying the speed that you have with your glue. Oh well..

Thanks for the info...

Here is the the progress to date... [URL=http://www.sizzlesites.com/goose/index.html]Goose's SPAD Project[/URL]

Cheers all

Goose

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Why do i need to 'Flash'? - 7/21/2003 10:16:39 AM

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Another trick I found Sometimes when you fold your top half over to glue it the bottom likes to role the leading edge up ..Ive ended up with the wing curved on both sides .Like a fully semitrical wing ..So right or wroung what ill do is glue my spar down ..After its set up good get some cold wet wash cloths ..Ill take my torch and heat up the inside of the coro ..(( The part you wont see )) then ill hold the leading edge flat to the floor ..Yes I work on the floor L.O.L...Then i bow the Warm coro over the spars like i would when i glue it ..I put a board on the trailing edge to keep it down flat sometimes putting my knees on it and hold the leading edge down with one hand ..When its curved just the way you want it take your cold wet wash cloth and wipe it over the coro to cool it .. Once its cool i let go and ive got a nice flat bottom and a curved top thats alot easier to glue ..
Caution when you heat the coro it doesnt take much heat ..Keep your torch a moving to and heat up the whole half ..If you let it stand up staight it will just kinda sag if you watch it ..Also make sure your glue is set up good . The solvents in some glues are very flamable ..I was in a hurry one day and glue started on fire along with the wing ..My wife found no humer in a 48 inch burning piece of coro on her kitchen floor ..L.O.L...
I wonder if other guys do this ..No not the fire .. Heating the coro ..
Well Dude have fun and Good Luck to ya ..

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Why do i need to 'Flash'? - 7/21/2003 11:09:12 PM

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I have read a lot of threads on flashing and I still don't understand why there is such a controversy. All you have to do is forget to flash just once and there will be know doubt in your mind that flashing works (and I have the rejects to prove it.).

My personal opinion is that some people are using the wrong kind of torch. The basic propane torch used for plumbing is way to power full for flashing. I use a small handheld butane torch that seems to be just about the right heat as I have never had to throw away a piece of Coro because I melted it. I am sure somebody is successfully using a plumbing torch but take my word for it it is much easier with less heat.

As for the torch burning the oil's off of the Coro issue. If there is no oil on the coro then what is causing that rippling effect I see when I flash my Coro. If its just a heat wave than why don't I see it when I pass my torch over other surfaces.

I have tried the thinner and Scotchbrite method and it works but takes longer than flashing.

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Why do i need to 'Flash'? - 7/22/2003 2:21:30 AM

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Thanks Bobo...
You had me laughing!

and to you Captain.
I tried a couple of differing methods, and a quick sand with 100 grit paper and hot glue works the best for me.

The one good thing about buggering up my stab on the Mustang, is now I can use it for destruction testing

Cheers

Goose

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