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Post by flyingtigre on Mar 21, 2013 14:55:17 GMT -7
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rknrusty
Listener
Don't Panic!
Posts: 33
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Post by rknrusty on Mar 21, 2013 15:33:26 GMT -7
Most all of the glues we use in modeling make joints that are stronger than the wood around them. I've rebuilt some decades old models and found some glues last longer than others. When rebuilding, sometimes you can only guess what the original glue is, but I've seen what looks like common wood glue flaking and brittle. I've seen the same with Ambroid types of "airplane glue."
If we could test all of these glues by weathering them and occasionally pounding them into the ground over 20 years we might get a better idea of what the most resilient kind is.
I use 3 or 4 different types on different parts of a model for all the obvious reasons; weight, fuel resistance, ease of joining and aligning. I'm not saying the study isn't good information, just throwing in my glue thoughts.
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Post by bigiron on Mar 21, 2013 18:04:04 GMT -7
After more than 70 years of pounding models into the ground, trees, cars, houses, and posts, I have settled on Elmers and TiteBond for most Balsa to balsa or Balsa to spruce stuff, and slow setting Epoxy for engine mount areas. I use CA type glues as liquid pins only--- no structural joints due mostlt to its brittleness.
Bigiron
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Post by ukeyman5167 on Mar 22, 2013 15:56:54 GMT -7
In the past 3 or so years I have been using the Titebond moulding glue. (Black type instead of red or black typing on the bottle) It relly is simply great for about 1/2 of my glueing needs.
Joe
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Post by jehold66203 on Mar 22, 2013 17:33:18 GMT -7
I too have used about all the different type glues there is to use. Haven't been at it as long as some. A few years ago when CA was the rage, built a complete RC plane using only the thin CA, thick CA and one that had a blue tint to it. Lamnations required a lot of small holes in the inside lamination on the fuse sides. Sheeting LE and center on wing used slow CA. But,. the glue I use most now adays is good Elmers Glue All White Glue.
By the way, years ago I was going to redo an old Veco Thunderbird I had built in the early 60's using Testers Cement. The glue joints were all loose and the balsa so brittle I trashed the idea. Every thing I touched on it broke while trying to remove the old nylon covering.
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Post by gcb on Mar 22, 2013 22:52:06 GMT -7
... But,. the glue I use most now adays is good Elmers Glue All White Glue. I have used Elmer's Glue-All for years. Problem is , it's almost impossible to sand. When Tite-Bond came out it was much better for sanding. Formulas have changed over the years so I think most are similar these days. Sounds like it may have been a storage problem? The only saving grace of nylon covering (other than cost) was that after a crash you could walk over and pick up your bag-o-balsa and not have to pick up so many parts. :-) George Edit: I read that white glues should not be used on plywood to plywood joints because the glue used to bond the plywood layers together will not allow white glue to dry in a timely manner. Epoxy should be used for those situations. |
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rknrusty
Listener
Don't Panic!
Posts: 33
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Post by rknrusty on Mar 23, 2013 0:30:32 GMT -7
Edit: I read that white glues should not be used on plywood to plywood joints because the glue used to bond the plywood layers together will not allow white glue to dry in a timely manner. Epoxy should be used for those situations. That's good to know. I did not know that. |
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Post by Garf on Mar 23, 2013 6:49:10 GMT -7
In humid places (like Miami) Polyurethane glues (Gorilla Glue) works great for laminating provided it can be securely clamped. My Galaxy fuselage is made from 3 sheets of 1/8" balsa glued with Gorilla Glue plus the doublers glued with Gorilla Glue. No signs of delamination.
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Post by flyingtigre on Mar 26, 2013 19:41:46 GMT -7
I've not experienced problems with any of the adhesives commonly used in modeling but I do stick to a few simple guidelines.
First, stay away from all "fast" adhesives on hardwoods, plywood, or oily woods (like spruce). That includes fast curing epoxy.
Second, I have never heard of uncured glues like Elmer's or Titebond glues inside a joint where adequate drying time has been allowed before covering the surface with paint or film. See also #3.
Third, clamp whenever possible.
Fourth, when all else fails, follow the manufacturer's instructions.
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Post by marinaru on Mar 29, 2013 3:50:31 GMT -7
Well, the best glues used by me, lasting forever, are white glue and nitrocellulose. This second one is the balsa elixir in my opinion. Excepting the detail that lasting long time, there are very light (less weight then other glues). I made some tests and the conclusion was: white glue release 50% of its weight as evaporated wather. The nitrocellulose glue remain less then 30% from the initial amount, after the acetone is gone. The epoxy glue remain with similar weight, nothing is evaporating and also, the worst glue is cyanoacrylate (biggest liar, twice): first it looks like is a strong glue initialy, but after a while it's become a junk, its own internal conection cracking. The second liar is his weight: we are using just small drops and it looks to be veeeeery easy, but, in fact, it remain in same weight, nothing is evaporated. Now, would you like to talk about stiky fingers and iritated eyes with cyanoacrylate?....Nooooooooo  ;D Talking about prices, white glue and nitrocellulose are cheaper here then epoxy or superglues, especialy if we are buing them from the modelshops. Polyurethane glues (Gorilla Glue) works great for laminating Right! Also if you try to laminate carbon stringers with balsa sheets (or wood, genericaly speaking) gluing with polyurethane it is stronger then epoxy. if you will do it with epoxy, the carbon stringer will peel from the balsa easy. Also, regarding the epoxy, the faster epoxi is, the worst is it. Use epoxi for 24-48 hours, not minutes!!! white glues should not be used on plywood to plywood joints because the glue used to bond the plywood layers together will not allow white glue to dry in a timely manner. Epoxy should be used for those situations. In the past it was a glue made from animal bones or skin extract (gelatin...used also in pharmacies or to obtain food jellies), heated in the crock-pot surrounded by boiled whater (100Celsius degree). After it become fluid, spread it with the brush. It is good to glue surfaces, no need air to cure and its weight is lower then epoxy. I supose you can find it even today in shops for painters. Or, if you hate the smell, of this bone/skin glue, you can use polyester resign (stinky too ;D ). |
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Post by slobmaster on Mar 29, 2013 4:37:23 GMT -7
Is 30 min. epoxy okay for fuel proofing  What about fiberglass reinforced joints? |
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Post by marinaru on Mar 29, 2013 4:41:25 GMT -7
Is 30 min. epoxy okay for fuel proofing What about fiberglass reinforced joints? Usualy, I use epoxy resin for fuel proofing, not epoxy glue. This one (glue) become yellow-brown in time, ugly!  Am I right? Similar for fiberglass reinforced joints: epoxy resin or polyester resin, not glue!! if you need a thiner for epoxy, use a 50/50 acetone and methanol mixture; the epoxy have polarised and nonpolarised internal conections: acetone and methanol unfolding both tipes (works just to obtain a more fluid resign or glue, not working with cured epoxy; if somebody will find a thiner to transform the cured epoxy in fluid epoxi, I supose he will be eligible to obtain Nobel price, hehe!!). |
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Post by flyingtigre on Mar 29, 2013 10:40:25 GMT -7
I've used casting resin but shelf life was very poor. Used it so few times before it became a rock in a can, that I wasn't able to form an opinion on how good it is.
I've not found much difference in the common white glues. Strictly a personal choice.
I've used ca in applications dating back to the late 70's and in every instance where a problem occurred, the joint outlived the balsa.
I've stuck to the slowest epoxies wherever needed for a strong joint, faster curing should be fine for coating an engine well. Don't know if it's fact but I read where one of the popular 24 hour epoxies was the adhesive of choice for ultralights.
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Post by jehold66203 on Mar 30, 2013 7:50:26 GMT -7
Read the instructions on the Epoxy labels. I use 30 minute for laminates, wing/stab joints and engine mounts. 30 minute working time. 2 hours to stable joint. 24 hours to full cure. Epoxy does not dry, it cures by chemical reaction. I also think the new Gorilla Glue is great for laminations, especially when you do 1/4 inch fuselage sides for profiles. Makes for very very rigid profile fuse. And like Bigiron, the CA is just to hold things until I get the white glue out and start applying it to the joints. It will wick into the joints like CA. Well I need to get the camera out and get some pics taken of new project.
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Post by Garf on Jan 1, 2014 21:19:13 GMT -7
Gorilla Glue in action. Attachments:
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;D
What about fiberglass reinforced joints?
Am I right?