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BobHolmes

Glue question(s)

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As my grandson and I get further along in this a/c modeling thing, I have a general question or two about the glues we are using. From way way back in my beginning modeling days I remember that it is very important to make sure there is no paint on the two surfaces to be glued together and that we need to scrape off any that is. This is for our tube of Testors. I seem to remember that the same wasn't necessarily true for Elmer's, which I always used to attach canopies. Am I correct? And to carry my question further, how about Super Glue (although I used to try and avoid it because all I seemed to glue together was my fingers, and this was when I was a youngster)? And - my grandson found something online called Gator's Grip Hobby Glue and we ordered some of that (that is what granddads are for). In the little bottle it looks like Elmers to me, although thicker. If you have used it, do surfaces need to be paint free for it also? I'd appreciate your thoughts on this, and maybe sharing your expertise with us. Thank you very much.

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Basically, all of the types work best plastic to plastic. This is because if a glue only binds itself to the paint layer, then THAT is what it holds onto, and not the part itself. Most plastic model cements (tube, liquid, or weld type) will eat through that paint at least to some degree to give you a better bond. But, once more, plastic to plastic is always the strongest bond..

 

Most of us use liquid cements or liquid "weld" types instead of tube glue. It's just as strong, easier to apply with a small brush, and sets faster. You apply it differently than the tube stuff, in that you hold the parts together and apply a drop to the seam, letting capillary action carry the glue about 1/2" down the seam. Press it tightly together to get it to "weld" together. When used properly, you can even get a "molten" bead of plastic to pop up from the seam helping fill it as you work your way around the part. The liquid actually evaporates away for the most part, so there's not really any "glue" there holding the parts (unlike the tube cement).

 

Superglue is VERY convenient, but don't try to apply it from the bottle! First of all, more superglue does NOT make for a better bond or faster setting. In fact, it usually works the opposite way! I use an old butter tub lid to put a drop or two onto, and then use a toothpick or small wire to apply the glue where needed. Since you have less time for adjustments, you want to use this only where you're pretty sure of a positive fit and alignment on the first go. It's main advantages are speed and tensile strength (when you pull on it). The down side is poor shear strength (if bumped from the side).

 

White glues, Elmers, the Gorilla Grip glue (not to be confused with the Gorilla brand superglues) do not evaporate away. It's the glue itself that "sticks" to the parts and makes the bond, which is also why plastic to plastic is better than paint to paint. The strength of the glue doesn't matter if it's only the strength of the paint to the plastic that's holding it together! Their advantages are that they do not attack plastic or paint, and thus are much less likely to ruin a paint job or fog a clear part (like superglue fumes can). Their disadvantage is that they're not as strong. They work well for holding parts in place that bear no load (like a canopy).

 

All of them have their advantages and disadvantages depending on the job at hand and your level of patience! Hope this helps!

 

GIL :smiley16:

Edited by ghodges

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Basically, all of the types work best plastic to plastic. This is because if a glue only binds itself to the paint layer, then THAT is what it holds onto, and not the part itself. Most plastic model cements (tube, liquid, or weld type) will eat through that paint at least to some degree to give you a better bond. But, once more, plastic to plastic is always the strongest bond..

 

Most of us use liquid cements or liquid "weld" types instead of tube glue. It's just as strong, easier to apply with a small brush, and sets faster. You apply it differently than the tube stuff, in that you hold the parts together and apply a drop to the seam, letting capillary action carry the glue about 1/2" down the seam. Press it tightly together to get it to "weld" together. When used properly, you can even get a "molten" bead of plastic to pop up from the seam helping fill it as you work your way around the part. The liquid actually evaporates away for the most part, so there's not really any "glue" there holding the parts (unlike the tube cement).

 

Superglue is VERY convenient, but don't try to apply it from the bottle! First of all, more superglue does NOT make for a better bond or faster setting. In fact, it usually works the opposite way! I use an old butter tub lid to put a drop or two onto, and then use a toothpick or small wire to apply the glue where needed. Since you have less time for adjustments, you want to use this only where you're pretty sure of a positive fit and alignment on the first go. It's main advantages are speed and tensile strength (when you pull on it). The down side is poor shear strength (if bumped from the side).

 

White glues, Elmers, the Gorilla Grip glue (not to be confused with the Glorilla brand superglues) do not evaporate away. It's the glue itself that "sticks" to the parts and makes the bond, which is also why plastic to plastic is better than paint to paint. The strength of the glue doesn't matter if it's only the strength of the paint to the plastic that's holding it together! Their advantages are that they do not attack plastic or paint, and thus are much less likely to ruin a paint job or fog a clear part (like superglue fumes can). Their disadvantage is that they're not as strong. They work well for holding parts in place that bear no load (like a canopy).

 

All of them have their advantages and disadvantages depending on the job at hand and your level of patience! Hope this helps!

 

GIL :smiley16:

Thank you very much for your response. I have learned from this, and will share it with my "partner" (grandson). Unfortunately, I forgot one other glue. It's epoxy that I order from Golfsmith. I have this around the house all the time since I make golf clubs and that's what I use to attach shafts to clubheads. Only negatives I can think of about it is that it smells to high heaven, takes pretty long to set up, and dries black. Would it be good to use for landing gear and those type parts where I could hide it? It is definitely strong. I haven't lost a clubhead yet that I know of. Is the plastic to plastic thing as relevant as with the others? Thanks again for your help for one old and not very smart.

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Epoxy is a well known glue with modelers, especially those that build vacuforms and scratch build models. We generally use epoxies that set in 5-10 minutes or no more than an hour. Personally, I've used 2 part liquid and putty types from the hardware store; as well as some "hobby" epoxies like Apoxy Sculp and Milliput. The advantage to the epoxies designed for the modeling hobby is that they're generally easier to sand and finish compared to hardware types, but they're also more expensive (by volume). Otherwise, they mix and handle in very similar ways. Also, there are plenty of liquid epoxies that dry clear and can be used for clear parts, to fill window openings, and even make clear lights.

 

Epoxies are generally used only where great strength is needed, where dissimilar materials need to be bonded (like metal to plastic), and/or where you need time to set the alignment. Liquid epoxies are generally used for attaching parts (like landing gear and wings), while solid putty epoxies are used to fill and strengthen large joints and gaps, acting as a glue and filler at the same time. Most of us just use liquid cement or super glue to attach landing gear because epoxy is too messy and slow by comparison, unless extra strength is a need.

 

By the way, "Gorilla" makes a super glue with rubber in it that makes it more like an epoxy. It has the strength and speed of superglue, while the rubber gives it greater shear strength, though it's not as strong as epoxy.

 

There is no "wrong" glue to use on a model, it just depends on what you perceive are your needs and what conveniences you're looking for. Lastly, don't put yourself down! Your questions are the same ones we all have asked when we first started. We're not smarter, just more experienced!

 

GIL :smiley16:

Edited by ghodges

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Gator glue is great for photo-etch and glass.The guy that makes it is in my club.

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